---
slug: water-under-tension
passed: 2026-10-18
by: the assay line (research/assay-line/claude-1018c/), Claude fixer (claude-opus-5-5) directed by claude-assaying-boyle-1014; source record by a Claude agent (claude-sonnet-5-5), checked by a Claude agent (claude-opus-5-5)
checked: 124
confirmed: 93
wrong: 18             # 6 WRONG + 12 MINOR
unverifiable: 10
observed: 3
stale: 0
---

This was a directed repair pass over the 18 triage items in research/assay-line/claude-1018c/water-under-tension/triage.json, read at e7c21dfcc4 (the checker read the layer at 685fdbaa44). The checker raised six WRONG lines and twelve MINOR. The fixer re-read the evidence for each WRONG line itself: a fresh run of the layer's verifier ("ALL 68 CHECKS PASSED", against the "66 offline checks" in the dek and source note; the same run prints "Psi_grav = -1.1332 MPa" and "P_abs = -1.0318 MPa" for Hyperion), the page's own dFromP50 (4 * gam * COS_THETA / |P50|, so a non-zero contact angle shrinks the inferred pore), Wei, Tyree and Steudle 1999 (PMC59486: an oil-filled cell pressure probe that "should be safe to -1 MPa"; water-filled probes cavitated "at -0.6 to -0.7 MPa"; no -0.65 MPa recording limit), and Crossref for doi 10.1111/pce.13654 (first author Ya Zhang). All six are fixed on the page, in the markdown and, where the README repeats them, in research/water-under-tension/README.md, with five dated Corrected lines (the two 66-check lines share one) in a new Corrections note on the page and mirrored in the markdown; JSON-LD dateModified moved to 2026-10-18. All twelve MINOR lines were cheap and are fixed with no page line; the Zhang 2020 wording (two lines) was re-read in the paper's section 4.4 and Maherali et al. 2004's P50 range in its abstract. The layer's verifier passes 68 of 68 after the edits. The record carries forward the checker's 124 claim lines from research/assay-line/claude-1018c/water-under-tension/N2-claude.md, including its CONFIRMED, OBSERVED and UNVERIFIABLE lines, without claiming a fresh audit of them. The checker's one open note was against the source record (N1), not the page, and is left with it.

## Claims
- MINOR | [ceiling-10-33] Put a perfect vacuum pump on top of a pipe and it will lift water 10.33 metres. | https://en.wikipedia.org/wiki/Standard_atmosphere_(unit); https://en.wikipedia.org/wiki/Siphon; https://en.wikipedia.org/wiki/Water_(data_page) | The excerpt is a unit equivalence ("1 atm ... ≈ 10.33 m H2O", footnoted as "an ideal column of water with density of 1000 kg/m3"), not what a pump lifts. A perfect vacuum above water leaves the column top at water's vapour pressure, and Siphon says the maximal height "is limited by the vapour pressure of the liquid". From the Water data page formula (A 7.2326, B 1750.286, C 38.1) p_vap is 2.34 kPa at 20 C, so the lift is (101325 − 2339)/(998.2 × 9.80665) = 10.11 m at 20 C, 10.21 m at 10 C. The page says "Not 10.4" and names density (1.9 cm) among "Every free choice on this page, named" but not vapour pressure (about 22 cm).
- CONFIRMED | [ceiling-arith] The famous 10.33 m is the 1000 kg/m³ version. | recreated: node verify-water-under-tension.mjs fetched from https://artwaste.land/checks/research/water-under-tension/verify-water-under-tension.mjs (byte-identical to 685fdbaa44), "ALL 68 CHECKS PASSED", exit 0 | "rho = 1000 kg/m^3 -> ceiling 10.3323 m"; 101325/(1000 × 9.80665) = 10.332 m by hand.
- MINOR | [atm-defn] One standard atmosphere is defined as the pressure under 760 mm of mercury | https://en.wikipedia.org/wiki/Standard_atmosphere_(unit) | Source: "a unit of pressure defined as 101325 Pa" and "was originally defined as the pressure exerted by a 760 mm column of mercury at 0 C". The page says "is defined as" the 760 mm column, the superseded definition; the equivalence holds (verifier: 101325.01 Pa), the tense does not.
- CONFIRMED | [hg-density] and mercury is 13 595 kg/m³ | https://en.wikipedia.org/wiki/Millimetre_of_mercury | "with a density of 13595.1 kg/m3 (approximate density at 0 C)".
- CONFIRMED | [mm-water] so 101 325 Pa is also the pressure under 10 332 mm of water. | recreated: node verify-water-under-tension.mjs fetched from https://artwaste.land/checks/research/water-under-tension/verify-water-under-tension.mjs (byte-identical to 685fdbaa44), "ALL 68 CHECKS PASSED", exit 0 | "P_atm expressed as a water column = 10332 mm".
- CONFIRMED | [std-gravity] standard gravity (9.80665 m/s²) | https://en.wikipedia.org/wiki/Standard_gravity | "a constant defined by ISO standard 80000 as 9.80665 m/s2".
- CONFIRMED | [suction-not-a-force] Suction cannot beat it because suction is not a force. | https://en.wikipedia.org/wiki/Suction (the record's Suction_pump URL redirects to Vacuum pump#History, which supports only the ceiling) | Suction: "the forces acting in this case do not originate from just the lower pressure side, but instead from the side of the higher pressure" and "the objects are not pulled but pushed" (both tagged citation needed); a straw: "the atmospheric pressure on the fluid in the glass pushes the liquid up".
- CONFIRMED | [farm-well] Farm well pumps hit this every day. | https://en.wikipedia.org/wiki/Hand_pump | Record had no source. Hand pump: "Suction pumps 0–7 meters" and "a height above that to which a suction or lift pump will operate effectively (about seven metres)". The working limit is below 10.33 m, so well suction pumps do meet the ceiling; "every day" is colloquial.
- MINOR | [cap-three-orders] and xylem conduits are not narrow enough by three orders of magnitude: | recreated: node verify-water-under-tension.mjs fetched from https://artwaste.land/checks/research/water-under-tension/verify-water-under-tension.mjs (byte-identical to 685fdbaa44), "ALL 68 CHECKS PASSED", exit 0; arithmetic by hand | The excerpt ("r = 5 um gives capillary rise under 3 m") does not bear on "three orders". To hold the 115.55 m Hyperion column by capillarity needs r = 2γ/(ρgh) = 0.1455/(9806.65 × 115.55) = 128 nm. The table's conduits are 5 to 100 um: 39× to 780× too wide, i.e. 1.6 to 2.9 orders, not three; against the 10.33 m ceiling it is 3.5× to 70×.
- CONFIRMED | [cap-no-3m] Nothing in a stem lifts water even three metres by capillarity. | recreated: node verify-water-under-tension.mjs fetched from https://artwaste.land/checks/research/water-under-tension/verify-water-under-tension.mjs (byte-identical to 685fdbaa44), "ALL 68 CHECKS PASSED", exit 0 | "r = 5 um (narrow tracheid) -> 2.967 m"; true for every radius in the table (narrowest 5 um). Whether any stem conduit is narrower was not checked.
- CONFIRMED | [cap-5nm-km] A meniscus that small can hold a column kilometres tall. | recreated: node verify-water-under-tension.mjs fetched from https://artwaste.land/checks/research/water-under-tension/verify-water-under-tension.mjs (byte-identical to 685fdbaa44), "ALL 68 CHECKS PASSED", exit 0 | "5 nm pore column height = 2967 m".
- CONFIRMED | [leaf-pores-nm] whose pores are a few nanometres across | Carpita, Sabularse, Montezinos & Delmer, Science 205:1144-1147 (1979), https://doi.org/10.1126/science.205.4411.1144 (Europe PMC abstract) | Record had no source. "45 to 52 angstroms for isolated palisade parenchyma cells of the leaves of Xanthium strumarium and Commelina communis" (4.5 to 5.2 nm across). The table row uses 5 nm as a radius (10 nm across), conservative for the point made.
- CONFIRMED | [leaf-menisci] The menisci that matter are not in the conduits at all, they are in the | https://en.wikipedia.org/wiki/Transpiration | "increases the tension on the water menisci in the cell walls and decreases their radius".
- CONFIRMED | [dixon-joly] That is the cohesion-tension mechanism, proposed by Dixon and Joly in 1894, and it is the accepted account of how sap moves. | https://en.wikipedia.org/wiki/Xylem#Cohesion-tension_theory (the record's Cohesion-tension_theory URL redirects here); Angeles et al., New Phytol 163:451-452 (2004), doi 10.1111/j.1469-8137.2004.01142.x (OpenAlex abstract) | Xylem: "It was proposed in 1894 by John Joly and Henry Horatio Dixon" (Annals of Botany 8:468-470, 1894). Accepted account: Angeles et al. (45 signatories) "the Cohesion-Tension theory is widely supported as the only theory consistent with the preponderance of data on water transport in plants".
- CONFIRMED | [metastable] Water under negative absolute pressure is metastable. | https://pmc.ncbi.nlm.nih.gov/articles/PMC59486/ (Wei, Tyree & Steudle 1999) | "water under tension is in a metastable state and should cavitate immediately when gas seeds are around".
- CONFIRMED | [zimmermann-canny] This is the objection Zimmermann, Canny and others pressed hard through the 1990s, some of them arguing that the tension was an artefact of the pressure chamber itself. | https://pmc.ncbi.nlm.nih.gov/articles/PMC59486/ (Wei, Tyree & Steudle 1999) | "the cohesion-tension (CT) theory ... has been questioned (Balling and Zimmermann, 1990; Benkert et el., 1991; Zimmermann et al., 1993)", "Early pressure probe results have failed to corroborate the pressure bomb", alternatives "somewhat exotic (Canny, 1995)". Angeles et al. 2004 shows Zimmermann still pressing it in 2004.
- CONFIRMED | [tree-thousand-years] for a thousand years | https://en.wikipedia.org/wiki/Sequoia_sempervirens | "has reached ages of about 2,000 years".
- UNVERIFIABLE | [textbook-borrowed-time] Every textbook of liquid-state physics says such a liquid is living on borrowed time. | none found; Wei 1999 and Choat 2003 read | A claim about every textbook of a field; the record searched none and neither did I. The physics it stands for (metastability) is confirmed above.
- CONFIRMED | [not-homogeneous-nucleation] xylem does not fail by homogeneous nucleation. | https://pmc.ncbi.nlm.nih.gov/articles/PMC166785/ (Choat et al. 2003); https://pmc.ncbi.nlm.nih.gov/articles/PMC59486/ (Wei, Tyree & Steudle 1999) | Choat 2003 frames failure as air seeding, "The pressure gradient (ΔP) in MPa required to pull an air bubble through a pit membrane pore"; its alternative is also heterogeneous ("vapor embryos in hydrophobic cell wall interstices"); Wei: "liquids withstand high tensile stresses of up to several-hundred megapascals".
- CONFIRMED | [pure-water-strong] Pure water in a clean vessel is famously strong, and would need far more tension than a tree ever generates. | https://pmc.ncbi.nlm.nih.gov/articles/PMC59486/ (Wei, Tyree & Steudle 1999); https://arxiv.org/html/2501.19039v1 | Wei: "up to several-hundred megapascals"; arXiv: purified water reaches "about −30 MPa", inclusions "up to −140 MPa", against tree tensions of a few MPa.
- CONFIRMED | [pit-membrane-mesh] Neighbouring conduits share a pit membrane, a porous mesh of cell wall. | https://www.ebi.ac.uk/europepmc/webservices/rest/search?query=EXT_ID:18086228%20AND%20SRC:MED&format=json&resultType=core (Choat, Cobb & Jansen 2008 abstract) | "The pit membrane ... allows water to pass between xylem conduits"; "large differences evident in the porosity and thickness of pit membranes".
- CONFIRMED | [young-laplace-law] The threshold for pushing a meniscus through a pore of diameter | https://pmc.ncbi.nlm.nih.gov/articles/PMC166785/ (Choat et al. 2003) | Equation 1 is an image, but Table III fixes it: 4 × 0.0728/3.17 MPa = 92 nm against the published 90 nm, so ΔP = 4τcosθ/D with "The contact angle (θ) ... assumed to be 0".
- CONFIRMED | [choat2003-four] Choat and colleagues measured vulnerability curves on four co-existing dry rainforest trees in 2003 | https://pmc.ncbi.nlm.nih.gov/articles/PMC166785/ (Choat et al. 2003) | Abstract: two drought-deciduous and two evergreen species "growing in a seasonally dry rainforest"; Table III gives "inter-vessel pit membrane pore diameter (D) calculated from Equation 1".
- CONFIRMED | [choat2003-diam-calc] Those diameters were calculated from the P50s, not observed | https://pmc.ncbi.nlm.nih.gov/articles/PMC166785/ (Choat et al. 2003) | "The average maximum pore diameter in pit membranes was calculated for the ΔP producing a PLC of 50 using Equation 1".
- CONFIRMED | [t-cochlo] ['Cochlospermum gillivraei', -1.44, 200] | https://pmc.ncbi.nlm.nih.gov/articles/PMC166785/ (Choat et al. 2003) | Abstract "−1.44 MPa"; Table III "C. gillivraei 1.43 200" (the table rounds ΔP to 1.43).
- CONFIRMED | [t-brachy] ['Brachychiton australis', -3.17, 90] | https://pmc.ncbi.nlm.nih.gov/articles/PMC166785/ (Choat et al. 2003) | Abstract "−3.17 MPa"; Table III "B. australis 3.17 90".
- CONFIRMED | [t-austro] ['Austromyrtus bidwillii', -5.12, 60] | https://pmc.ncbi.nlm.nih.gov/articles/PMC166785/ (Choat et al. 2003) | Abstract "−5.12 MPa in A. bidwillii"; Table III "A. bidwillii 5.12 60".
- CONFIRMED | [t-alphi] ['Alphitonia excelsa', -5.56, 50] | https://pmc.ncbi.nlm.nih.gov/articles/PMC166785/ (Choat et al. 2003) | Abstract "−5.56 MPa in A. excelsa"; Table III "A. excelsa 5.56 50".
- MINOR | [choat2003-no-see] The 2003 paper tried to see the predicted pores directly, by scanning electron microscopy and by colloidal gold perfusion, and could not resolve them. | https://pmc.ncbi.nlm.nih.gov/articles/PMC166785/ (Choat et al. 2003) | SEM did not resolve them ("pores were not visible to a resolution of 20 nm"), but the gold perfusion was not a failure to resolve: it measured the pores, "These experiments indicated that pit membrane pores were between 5 and 20 nm in diameter in all four species", and the Discussion says the study "did not confirm the existence of pores above 20 nm". The method found pores smaller than predicted; it did not fail to see them.
- CONFIRMED | [choat2003-one-site] The four values in our table are from bench-dehydration curves in one paper on four species at one site. | https://pmc.ncbi.nlm.nih.gov/articles/PMC166785/ (Choat et al. 2003) | "growing in north Queensland at Many Peaks Range"; branches "allowed to dehydrate under laboratory conditions".
- CONFIRMED | [choat2003-default] Default is Brachychiton australis from Choat 2003. | https://pmc.ncbi.nlm.nih.gov/articles/PMC166785/ (Choat et al. 2003) | "B. australis ... reached a 50% loss of hydraulic conductivity at −3.17 MPa"; the slider default is −3.17.
- CONFIRMED | [ysl-within-5-3] lands on the pore diameters the same paper published, within 5.3%. | recreated: node verify-water-under-tension.mjs fetched from https://artwaste.land/checks/research/water-under-tension/verify-water-under-tension.mjs (byte-identical to 685fdbaa44), "ALL 68 CHECKS PASSED", exit 0 | deltas "1.0%", "2.0%", "5.3%", "4.7%"; worst 5.3%.
- CONFIRMED | [zhang-7-2] pure water in a 20 nm constriction should hold to about 7.2 MPa, far past where real plants actually embolise | https://oparu.uni-ulm.de/server/api/core/bitstreams/a0bedabe-c04f-494a-8970-ee5236f07c99/content (Zhang et al. 2020 PDF, read with pdftotext) | Section 4.4: "would be 7.2 MPa in pure water" and "embolisms form in almost all plant species at pressure differences far less than the 7.2 MPa predicted for 20 nm pore constrictions if sap was pure water".
- MINOR | [zhang-surfactants] they attribute the gap to surface-active substances in sap lowering | https://oparu.uni-ulm.de/server/api/core/bitstreams/a0bedabe-c04f-494a-8970-ee5236f07c99/content (Zhang et al. 2020 PDF, read with pdftotext) | Zhang does say "the surface tension inside pores is likely to be much reduced" because surfactants "are known to occur in xylem sap". But it does not attribute the gap to them: with lipid surface tension the threshold is still 2.4 MPa, and embolism forms "for most species also at pressure differences less than 2.4 MPa predicted for surface tension in the presence of surface-active lipids", so "the narrow constriction sizes ... raise questions about the classic air-seeding mechanism".
- CONFIRMED | [zhang-recompute] recomputes here as 7.27 MPa. | recreated: node verify-water-under-tension.mjs fetched from https://artwaste.land/checks/research/water-under-tension/verify-water-under-tension.mjs (byte-identical to 685fdbaa44), "ALL 68 CHECKS PASSED", exit 0 | "20 nm pore with a 0.5 shape factor -> 7.2 MPa (Zhang et al. 2020) 7.27 MPa"; 0.5 × 4 × 0.07275/20e-9 = 7.275 MPa by hand.
- CONFIRMED | [zhang-year-2020] Zhang and colleagues (2020), whose 20 nm figure this page cross-checks | https://oparu.uni-ulm.de/server/api/core/bitstreams/a0bedabe-c04f-494a-8970-ee5236f07c99/content (Zhang et al. 2020 PDF, read with pdftotext); Crossref 10.1111/pce.13654 | "Accepted: 10 September 2019"; volume 43 (2020). The volume year is 2020; online 2019.
- CONFIRMED | [gamma-72-75] Pure water at 20 °C is 72.75. | https://en.wikipedia.org/wiki/Water_(data_page) | "72.75 dyn/cm at 20 C" (= mN/m).
- CONFIRMED | [sap-surfactants] Xylem sap is not pure water: it carries lipids and surfactants | https://oparu.uni-ulm.de/server/api/core/bitstreams/a0bedabe-c04f-494a-8970-ee5236f07c99/content (Zhang et al. 2020 PDF, read with pdftotext) | "surface-active substances, such as phospholipids, are known to occur in xylem sap".
- CONFIRMED | [rho-999-7] 999.7 kg/m³ (10 °C) | https://en.wikipedia.org/wiki/Water_(data_page) | "0.9997026 g/cm3 at 10 C".
- CONFIRMED | [rho-998-2] 998.2 kg/m³ (20 °C) | https://en.wikipedia.org/wiki/Water_(data_page) | "0.9982071 g/cm3 at 20 C".
- CONFIRMED | [rho-two-cm] A free choice worth about two centimetres of ceiling. | recreated: node verify-water-under-tension.mjs fetched from https://artwaste.land/checks/research/water-under-tension/verify-water-under-tension.mjs (byte-identical to 685fdbaa44), "ALL 68 CHECKS PASSED", exit 0 | 10.3509 − 10.3323 = 1.86 cm; "the density choice moves the ceiling by < 2 cm 1.9 cm".
- CONFIRMED | [rho-1-9cm] The whole choice is worth 1.9 cm | recreated: node verify-water-under-tension.mjs fetched from https://artwaste.land/checks/research/water-under-tension/verify-water-under-tension.mjs (byte-identical to 685fdbaa44), "ALL 68 CHECKS PASSED", exit 0 | as above, "1.9 cm".
- CONFIRMED | [ceiling-998] At 20 °C water is 998.2 and the ceiling is 10.35 m. | recreated: node verify-water-under-tension.mjs fetched from https://artwaste.land/checks/research/water-under-tension/verify-water-under-tension.mjs (byte-identical to 685fdbaa44), "ALL 68 CHECKS PASSED", exit 0 | "ceiling at rho=998.2 is 10.35 m 10.3509 m".
- CONFIRMED | [theta-assumption] This is an assumption, universal in the pit-membrane literature, not a measurement. | https://oparu.uni-ulm.de/server/api/core/bitstreams/a0bedabe-c04f-494a-8970-ee5236f07c99/content (Zhang et al. 2020 PDF, read with pdftotext); https://pmc.ncbi.nlm.nih.gov/articles/PMC166785/ (Choat et al. 2003) | Both assume it: Zhang "assuming a contact angle of zero"; Choat "is assumed to be 0". That it is "universal" in the literature rests on these two papers.
- UNVERIFIABLE | [theta-unmeasured] Nobody has measured the contact angle inside a pit pore. | Zwieniecki & Holbrook, Plant Physiol 123:1015-1020 (2000), doi 10.1104/pp.123.3.1015, Europe PMC abstract; Zhang 2020; Choat 2003 | A universal negative. The nearest measurement found is of the vessel lumen, not a pit pore: "The contact angle measured in the vessel lumen ranged between 42 degrees to 55 degrees". So the claim is not contradicted, and that paper shows xylem walls need not be at θ = 0.
- WRONG | [theta-larger-pore] A non-zero angle makes every inferred pore larger than we state. | public/strata/water-under-tension/index.html at 685fdbaa44 (function dFromP50) and Young-Laplace as the page prints it | The page's own inference is "D = 4γcosθ/|P50|" (dFromP50 returns 4 * gam * COS_THETA / ...). For θ > 0, cosθ < 1, so every inferred pore is SMALLER than the θ = 0 value, not larger. Example: θ = 40 degrees gives cosθ = 0.766, and B. australis's 92 nm becomes 70 nm.
- CONFIRMED | [gamma-50-31] Dropping γ to 50 mN/m shrinks every inferred pore by 31%. | recreated: node verify-water-under-tension.mjs fetched from https://artwaste.land/checks/research/water-under-tension/verify-water-under-tension.mjs (byte-identical to 685fdbaa44), "ALL 68 CHECKS PASSED", exit 0 | "lowering gamma from 72.75 to 50 mN/m moves the inferred pore by ~31% 92 nm -> 63 nm"; 1 − 50/72.75 = 31.3%.
- CONFIRMED | [shape-factor-half] Some authors apply a factor near 0.5. | https://oparu.uni-ulm.de/server/api/core/bitstreams/a0bedabe-c04f-494a-8970-ee5236f07c99/content (Zhang et al. 2020 PDF, read with pdftotext) | "a pore shape correction factor of 0.5 (Schenk et al., 2015)".
- CONFIRMED | [gravity-grad] Gravity's 0.0098 MPa/m is fixed by the weight of water. | recreated: node verify-water-under-tension.mjs fetched from https://artwaste.land/checks/research/water-under-tension/verify-water-under-tension.mjs (byte-identical to 685fdbaa44), "ALL 68 CHECKS PASSED", exit 0 | "gradient at rho=1000 is 0.00981 MPa/m 0.009807 MPa/m".
- CONFIRMED | [artefact-model-exp] so the fraction reaching the rotor axis is exp(−(D/2)/λ). | public/strata/water-under-tension/index.html at 685fdbaa44 | function fOpen(lam, D) { return Math.exp(-(D / 2) / lam); }: P(L > D/2) for an exponential with mean λ, as stated.
- CONFIRMED | [artefact-p50-steep] modelled as a steep sigmoid centred at −0.3 MPa. | public/strata/water-under-tension/index.html at 685fdbaa44 | var P50_ART = -0.30, S_ART = 120 (against S_TRUE = 50).
- CONFIRMED | [hyperion-2006] A coast redwood measured at 115.55 m in 2006 moves water to its top before breakfast. | https://en.wikipedia.org/wiki/Hyperion_(tree) | "The tree height of 115.55 m was verified by Stephen Sillett in 2006". "before breakfast" is a figure of speech.
- CONFIRMED | [hyperion-later] Hyperion was verified at 115.55 m by Stephen Sillett in 2006 using a tape drop; later listings give 116.07 m (2019) and 116.22 m (2026). | https://en.wikipedia.org/wiki/Hyperion_(tree) | "116.07 metres ... recorded in 2019"; "measured at 116.22 metres ... tall in 2026"; the 2006 method was "a laser range finder and a fiberglass tape to measure the tree from the base to the crown", which "tape drop" names in part.
- CONFIRMED | [hyperion-spread] The spread is worth 0.0066 MPa | recreated: node verify-water-under-tension.mjs fetched from https://artwaste.land/checks/research/water-under-tension/verify-water-under-tension.mjs (byte-identical to 685fdbaa44), "ALL 68 CHECKS PASSED", exit 0 | (116.22 − 115.55) × 0.009807 = 0.0066 MPa; "the 0.67 m of Hyperion remeasurement is worth only 0.0066 MPa".
- CONFIRMED | [koch-extrap] Koch's 122 to 130 m is a regression extrapolation, from height gradients in leaf functional traits, not an observed limit and not a law. | https://www.ebi.ac.uk/europepmc/webservices/rest/search?query=EXT_ID:15103376%20AND%20SRC:MED&format=json&resultType=core | "Our regression analyses of height gradients in leaf functional characteristics estimate a maximum tree height of 122-130 m barring mechanical damage".
- CONFIRMED | [koch-112] The tallest tree in that study was 112.7 m. | https://www.ebi.ac.uk/europepmc/webservices/rest/search?query=EXT_ID:15103376%20AND%20SRC:MED&format=json&resultType=core | "including the tallest known tree on Earth (112.7 m)".
- CONFIRMED | [koch-gravity] We draw it as a hatched band and label it as extrapolated. | public/strata/water-under-tension/index.html at 685fdbaa44 | "// Koch's extrapolated band, hatched" and c.fillText('KOCH 122–130 m (EXTRAPOLATED)', ...).
- CONFIRMED | [choat2012-226] Choat and 23 co-authors assembled these for 226 species at 81 sites in 2012 | https://repository.naturalis.nl/document/495587 (Choat et al. 2012 PDF) and Europe PMC abstract, doi 10.1038/nature11688 | 24 authors listed (Choat and 23 others); "70% of 226 forest species from 81 sites worldwide". The 226 are those with Ψmin ("available for 226 of the 480 species included in our database").
- CONFIRMED | [choat2012-70] Their finding: 70% of species run on margins under 1 MPa, and those margins are largely independent of mean annual precipitation. | https://repository.naturalis.nl/document/495587 (Choat et al. 2012 PDF) and Europe PMC abstract, doi 10.1038/nature11688 | "70% of 226 forest species ... operate with narrow (<1 megapascal) hydraulic safety margins"; "Safety margins are largely independent of mean annual precipitation".
- MINOR | [choat2012-rainforest-desert] Rainforests are as close to the edge as deserts. | https://repository.naturalis.nl/document/495587 (Choat et al. 2012 PDF) and Europe PMC abstract, doi 10.1038/nature11688 | The paper is about forests: "all forest biomes equally vulnerable to hydraulic failure regardless of their current rainfall environment"; its biomes run from Mediterranean woodland to tropical rain forest, "mean annual precipitation (MAP) ranged from 300 to 4,500 mm". No desert biome is in it; "as deserts" should read "as the driest forests and woodlands".
- CONFIRMED | [choat2012-margin-defn] compared each species' P50 to the lowest water potential it actually experiences in the field. | https://repository.naturalis.nl/document/495587 (Choat et al. 2012 PDF) and Europe PMC abstract, doi 10.1038/nature11688 | "Ψmin data are the minimum midday water potential recorded for each species in the field"; "the Ψ50 margin (Ψmin − Ψ50)".
- CONFIRMED | [choat2012-34-gap] The gap is the hydraulic safety margin. | https://repository.naturalis.nl/document/495587 (Choat et al. 2012 PDF) and Europe PMC abstract, doi 10.1038/nature11688 | "The difference between Ψmin and Ψ50 represents a highly informative 'safety margin'".
- MINOR | [p50-range] Published P50 spans roughly –0.5 to –14 MPa across woody plants | Maherali, Pockman & Jackson, Ecology 85:2184-2199 (2004), https://doi.org/10.1890/02-0538 (Europe PMC abstract) | Source: "ranged from −0.18 to −9.9 MPa for angiosperms and from −1.5 to −14.1 MPa for conifers". The low end is −0.18, not "roughly −0.5"; the span is about −0.2 to −14 MPa.
- CONFIRMED | [tr-diag] Torres-Ruiz and Cochard proposed a diagnostic in 2017 that needs no extra equipment: dry the sample to some tension first, then spin it at a less negative pressure than it has already survived. | https://www.ebi.ac.uk/europepmc/webservices/rest/search?query=EXT_ID:28467616%20AND%20SRC:MED&format=json&resultType=core | "exposed to less negative xylem pressures via centrifugation than the minimum pressure the sample had previously experienced"; "A simple test".
- CONFIRMED | [tr-clean] A clean sample cannot lose anything new, because it has already been past that point. | https://www.ebi.ac.uk/europepmc/webservices/rest/search?query=EXT_ID:28467616%20AND%20SRC:MED&format=json&resultType=core | "artefactual decreases in hydraulic conductance (k) for samples with open vessels when exposed to a less negative xylem pressure than the minimum pressure they had previously experienced".
- UNVERIFIABLE | [centrifuge-widely-used] It is fast, and it built the databases. | https://www.ebi.ac.uk/europepmc/webservices/rest/search?query=EXT_ID:28467616%20AND%20SRC:MED&format=json&resultType=core; Cochard et al., J Exp Bot 64:4779-4791 (2013), doi 10.1093/jxb/ert193 | Torres-Ruiz supports "widely used"; Cochard 2013: "Four methods accounted for more than 96% of all curves produced so far: bench dehydration-PLC, centrifugation-PLC, pressure sleeve-PLC, and Cavitron". "it built the databases" (rather than one of four methods that did) and "fast" are not in either abstract.
- CONFIRMED | [lopez-ratio] Lopez and colleagues (2019) find both centrifuge techniques prone to artefactual embolism when maximum vessel length is longer than or similar to rotor diameter | https://www.ebi.ac.uk/europepmc/webservices/rest/search?query=EXT_ID:30085232%20AND%20SRC:MED&format=json&resultType=core | "Both centrifuge techniques were prone to artefactual embolism in samples with maximum vessel length longer than, or similar to, the centrifuge rotor diameter".
- CONFIRMED | [lopez-mitig] Their own mitigations are procedural rather than mechanical: measure flow in an excised central part of the segment, start Cavitron runs below the threshold at which open vessels embolise, or correct with their CAVITOPEN model. | https://www.ebi.ac.uk/europepmc/webservices/rest/search?query=EXT_ID:30085232%20AND%20SRC:MED&format=json&resultType=core | "largely eliminated if flow was measured in an excised central part of the segment in the static centrifuge or starting measurements with the Cavitron at pressures lower than the threshold"; "a new model, CAVITOPEN".
- CONFIRMED | [sperry-2012] Sperry and colleagues argued in 2012 that not every "r"-shaped curve is invalid | https://www.ebi.ac.uk/europepmc/webservices/rest/search?query=EXT_ID:21988455%20AND%20SRC:MED&format=json&resultType=core | "'r' shaped curves are not necessarily artefacts".
- CONFIRMED | [venturas-2019] and Venturas and colleagues in 2019 compared four methods directly and found the divergence tracks vessel network structure. | https://www.ebi.ac.uk/europepmc/webservices/rest/search?query=EXT_ID:30997689%20AND%20SRC:MED&format=json&resultType=core | Title: "Direct comparison of four methods ...: Differences among techniques are linked to vessel network characteristics". The abstract puts it as "how losses in conductivity were evaluated".
- UNVERIFIABLE | [open-vessel-long-species] Species with long ones, many ring-porous and tropical angiosperms, are not. | Cochard et al. 2013 (doi 10.1093/jxb/ert193) abstract; Sperry 2012, Lopez 2019, Torres-Ruiz 2017 abstracts | Ring-porous half supported: "'Exponential' curves ... were remarkably frequent for species having large xylem conduits (ring-porous)" and "may reflect an open-vessel artefact". Nothing found for "tropical angiosperms".
- UNVERIFIABLE | [vessel-lengths] Diffuse-porous temperate species are centimetres. Ring-porous oaks and many lianas run to metres. | Europe PMC searches (vessel length with ring-porous/diffuse-porous; title "vessel-length distribution") | Only the overall range found: vessels "show a 100-fold variation, from less than a centimeter to many meters" (Pereira et al. 2020 bioRxiv, doi 10.1101/2020.08.04.234575). Positive control: the same search returned Ennajeh 2011 and Hacke 2006 abstracts naming ring- and diffuse-porous species, but no lengths by group.
- CONFIRMED | [wei-maize] The pressure-probe challenge of the 1990s was largely resolved in its favour, notably by Wei, Tyree and Steudle's maize work. | https://pmc.ncbi.nlm.nih.gov/articles/PMC59486/ (Wei, Tyree & Steudle 1999); Angeles et al. 2004 (doi 10.1111/j.1469-8137.2004.01142.x) | Wei: "Experiments were consistent with the cohesion-tension theory"; Angeles et al. list "Wei et al., 1999a; Wei et al., 1999b" among papers "which demonstrate that the fundamentals of the Cohesion-Tension theory remain valid". The 1999 paper's own "still ongoing" describes the state before its result.
- CONFIRMED | [wei-range] probe and pressure chamber agreed over the entire measured range of 0 to −0.7 MPa | https://pmc.ncbi.nlm.nih.gov/articles/PMC59486/ (Wei, Tyree & Steudle 1999) | "agreed over the entire measured range of 0 to −0.7 MPa".
- WRONG | [wei-probe-limit] and the probe's own apparatus could not record below about −0.65 MPa | https://pmc.ncbi.nlm.nih.gov/articles/PMC59486/ (Wei, Tyree & Steudle 1999) | The maize work used an oil-filled probe ("Xylem pressure was measured with an oil-filled cell pressure probe rather than the water-filled xylem pressure probe"). The −0.6 to −0.7 figure is the water-filled probes' cavitation point; "oil-filled probes at −1.3 to −1.4 MPa", "measurements with the cell pressure probe should be safe to −1 MPa. This was the range measured in this paper", and "P x = −1 MPa, which is the most negative pressure measured in this study". No "−0.65 MPa" limit appears.
- CONFIRMED | [wei-small-corner] That is a small corner of the range plants actually occupy | https://pmc.ncbi.nlm.nih.gov/articles/PMC59486/ (Wei, Tyree & Steudle 1999) | "considerably less negative than that proposed to exist in the xylem of some transpiring plants (−10 MPa ...)".
- CONFIRMED | [minus-10] come from pressure-chamber work on desert and chaparral species. | Kolb & Davis, Ecology 75:648-659 (1994), https://doi.org/10.2307/1941723 (Europe PMC abstract); Pockman & Sperry, Am J Bot 87:1287-1299 (2000), doi 10.2307/2656722 | Chaparral: "surviving water potentials as low as −9 MPa", measured seasonal minimum "−8MPa". Desert (record found none): Sonoran upland species, "the Ψ(x) experienced in upland habitats (−4 to −10 MPa)".
- CONFIRMED | [berthelot] Spinning-capillary and Berthelot-tube experiments have taken pure water to tensions of tens of megapascals in the laboratory | https://arxiv.org/html/2501.19039v1; Briggs, "Limiting Negative Pressure of Water", J Appl Phys 21:721 (1950), doi 10.1063/1.1699741 (Crossref title only) | arXiv: purified water "seem[s] to consistently reach a threshold of only about −30 MPa"; inclusions "similar to the Berthelot tube method ... up to −140 MPa". The spinning-capillary half rests on Briggs 1950, whose text was not read (Wei 1999 cites it).
- UNVERIFIABLE | [hbond-water] water does it unusually well because of hydrogen bonding | Wikipedia Xylem and Transpiration; arXiv 2501.19039 | Neither says water withstands tension "unusually well" because of hydrogen bonding. Not searched further.
- CONFIRMED | [root-pressure-fraction] But the pressures involved are typically a fraction of a megapascal, and that fraction buys metres, not hundreds of metres. | https://en.wikipedia.org/wiki/Root_pressure | "The maximum root pressure measured is about 0.6 megapascals"; "can raise water only to 6.87 meters".
- CONFIRMED | [root-pressure-guttation] it is why a cut grapevine bleeds in spring and why guttation drops appear on leaf margins at dawn. | https://en.wikipedia.org/wiki/Root_pressure; Grall et al., Appl Environ Microbiol 71:8292-8300 (2005), doi 10.1128/aem.71.12.8292-8300.2005; Sperry et al. 1987 (https://www.ebi.ac.uk/europepmc/webservices/rest/search?query=EXT_ID:16665259%20AND%20SRC:MED&format=json&resultType=core) | Guttation: "At night in some plants, root pressure causes guttation". Grapevine (Root pressure names only maple and elm, 0 hits for "grape"): Grall, "contaminated bleeding sap was observed during vine sprouting"; Sperry 1987, spring "root pressures between 10 and 100 kilopascals" in grapevines.
- CONFIRMED | [root-pressure-absent] It is also absent in many species during active transpiration, precisely when the demand is highest. | https://en.wikipedia.org/wiki/Root_pressure | "When transpiration is high, xylem sap is usually under tension, rather than under pressure"; "some species never generate any root pressure".
- CONFIRMED | [root-pressure-refill] It refills embolised conduits in some plants; it does not run the column. | https://www.ebi.ac.uk/europepmc/webservices/rest/search?query=EXT_ID:16665259%20AND%20SRC:MED&format=json&resultType=core | "filled with xylem sap and recovered their maximum hydraulic conductance ... During this period root pressures between 10 and 100 kilopascals were measured".
- CONFIRMED | [root-pressure-real] Root pressure, generated osmotically, is real | https://en.wikipedia.org/wiki/Root_pressure | "Root pressure is the transverse osmotic pressure within the cells of a root system".
- WRONG | [checks-66-dek] 66 offline checks. | recreated: node verify-water-under-tension.mjs fetched from https://artwaste.land/checks/research/water-under-tension/verify-water-under-tension.mjs (byte-identical to 685fdbaa44), "ALL 68 CHECKS PASSED", exit 0; the same file at the birth commit b03ce7088d1 also prints "ALL 68 CHECKS PASSED" | src/content/strata/water-under-tension.md dek: "66 offline checks." The verifier had 68 checks when the layer was written (b03ce7088d1) and at the pin; the page itself says "(68 checks, exits 0)". False from birth, so WRONG, not STALE.
- WRONG | [checks-66-body] 66 offline checks: | recreated: node verify-water-under-tension.mjs fetched from https://artwaste.land/checks/research/water-under-tension/verify-water-under-tension.mjs (byte-identical to 685fdbaa44), "ALL 68 CHECKS PASSED", exit 0; birth commit b03ce7088d1 verifier prints 68 | src/content/strata/water-under-tension.md body: "verify-water-under-tension.mjs, 66 offline checks:". Same 68; research/water-under-tension/README.md also says "66 checks".
- OBSERVED | [checks-68-check-panel] (68 checks, exits 0) | recreated: node verify-water-under-tension.mjs fetched from https://artwaste.land/checks/research/water-under-tension/verify-water-under-tension.mjs (byte-identical to 685fdbaa44), "ALL 68 CHECKS PASSED", exit 0 | Reproduced exactly: 68 "ok" lines, exit 0.
- MINOR | [nothing-stored] Nothing on this page is a stored number. | public/strata/water-under-tension/index.html at 685fdbaa44 | The readouts are recomputed in the browser, but prose numbers are typed text, not computed: "73.8% at 50 cm, 6.5% at 5 cm, and only at about 2 cm does it drop to 0.11%", "falls from 0.763 to 0.067", "worth 1.9 cm", "shrinks every inferred pore by 31%", "0.0066 MPa", and the four Choat values and tree heights are stored inputs. All agree with the verifier, so this overstates the mechanism, not the figures.
- CONFIRMED | [margin-default] true margin is +0.77 MPa | recreated: node verify-water-under-tension.mjs fetched from https://artwaste.land/checks/research/water-under-tension/verify-water-under-tension.mjs (byte-identical to 685fdbaa44), "ALL 68 CHECKS PASSED", exit 0 | "true safety margin +0.77 MPa becomes an apparent deficit of −1.97 MPa".
- CONFIRMED | [r-shape-55] r-shaped: 55.3% loss at only −0.5 MPa, where the true curve loses 0.5% | recreated: node verify-water-under-tension.mjs fetched from https://artwaste.land/checks/research/water-under-tension/verify-water-under-tension.mjs (byte-identical to 685fdbaa44), "ALL 68 CHECKS PASSED", exit 0 | "contaminated curve shows 55.3% loss at only −0.5 MPa"; "the TRUE curve at −0.5 MPa shows under 1% loss 0.477%".
- CONFIRMED | [open-fraction-0-763] the open-vessel fraction falls from 0.763 to 0.067 | recreated: node verify-water-under-tension.mjs fetched from https://artwaste.land/checks/research/water-under-tension/verify-water-under-tension.mjs (byte-identical to 685fdbaa44), "ALL 68 CHECKS PASSED", exit 0 | "open fraction 0.7634"; "f falls to 0.067 f = 0.0672".
- CONFIRMED | [diag-73-8] Walk λ down and watch the same diagnostic fall: 73.8% at 50 cm, 6.5% at 5 cm, and only at about 2 cm does it drop to 0.11% | recreated: node verify-water-under-tension.mjs fetched from https://artwaste.land/checks/research/water-under-tension/verify-water-under-tension.mjs (byte-identical to 685fdbaa44), "ALL 68 CHECKS PASSED", exit 0 | "73.78%", "6.49%", "0.11%".
- CONFIRMED | [p50-walk-2-7] the fitted P50 walk 2.7 MPa | recreated: node verify-water-under-tension.mjs fetched from https://artwaste.land/checks/research/water-under-tension/verify-water-under-tension.mjs (byte-identical to 685fdbaa44), "ALL 68 CHECKS PASSED", exit 0 | "shift = 2.738 MPa".
- CONFIRMED | [diag-clean-zero] which is exactly zero for a clean sample | recreated: node verify-water-under-tension.mjs fetched from https://artwaste.land/checks/research/water-under-tension/verify-water-under-tension.mjs (byte-identical to 685fdbaa44), "ALL 68 CHECKS PASSED", exit 0 | "diagnostic on a clean sample (f=0) returns exactly 0% new loss".
- WRONG | [hyperion-p-abs] which is what gravity alone demands at the top of Hyperion | recreated: node verify-water-under-tension.mjs fetched from https://artwaste.land/checks/research/water-under-tension/verify-water-under-tension.mjs (byte-identical to 685fdbaa44), "ALL 68 CHECKS PASSED", exit 0; the page's own readout | Page: "Ψ = −1.03 MPa, which is what gravity alone demands at the top of Hyperion". −1.03 is the absolute pressure; the water potential gravity demands is −1.133 MPa (verifier "Psi = −1.1332 MPa, P_abs = −1.0318 MPa"; the page's own panel: "Water potential at the top −1.133 MPa", "Absolute pressure there −1.032 MPa"). The symbol and the number do not match.
- CONFIRMED | [zero-crossing] the required absolute pressure cross zero at exactly the barometric ceiling | recreated: node verify-water-under-tension.mjs fetched from https://artwaste.land/checks/research/water-under-tension/verify-water-under-tension.mjs (byte-identical to 685fdbaa44), "ALL 68 CHECKS PASSED", exit 0 | "absolute pressure hits zero exactly at the barometric ceiling 10.3323 m".
- CONFIRMED | [friction-zero] The zero-crossing height is unaffected by it only when it is zero. | public/strata/water-under-tension/index.html at 685fdbaa44 | var grad = gradMPa(st.rho) + st.fric; with friction the zero falls at P_atm/(ρg + friction), so it moves unless friction is 0.
- CONFIRMED | [sigmoid-slope] Two numbers describe it, the pressure at 50% loss (P50) and the slope there. | recreated: node verify-water-under-tension.mjs fetched from https://artwaste.land/checks/research/water-under-tension/verify-water-under-tension.mjs (byte-identical to 685fdbaa44), "ALL 68 CHECKS PASSED", exit 0 | "|slope| at P50 equals s (50 %/MPa) −50.0000".
- CONFIRMED | [pammenter-form] The sigmoid form: N. W. Pammenter & C. Vander Willigen, Tree Physiology 18 (1998). | https://pmc.ncbi.nlm.nih.gov/articles/PMC166785/ (Choat et al. 2003) | "PLC = 100/(1 + exp{a[Ψx − b]}) ... (Pammenter and Vander Willigen, 1998)".
- CONFIRMED | [cite-koch] G. W. Koch, S. C. Sillett, G. M. Jennings & S. D. Davis, "The limits to tree height," Nature 428:851–854 (2004) | https://www.ebi.ac.uk/europepmc/webservices/rest/search?query=EXT_ID:15103376%20AND%20SRC:MED&format=json&resultType=core | Koch GW, Sillett SC, Jennings GM, Davis SD; Nature 428:851-854, 2004; DOI MATCH.
- CONFIRMED | [cite-hyperion] Hyperion (tree), Wikipedia | https://en.wikipedia.org/wiki/Hyperion_(tree) | Page exists and carries all three figures.
- CONFIRMED | [cite-choat2003] B. Choat, M. Ball, J. Luly & J. Holtum, "Pit membrane porosity and water stress-induced cavitation in four co-existing dry rainforest tree species," Plant Physiology 131:41–48 (2003) | https://pmc.ncbi.nlm.nih.gov/articles/PMC166785/ (Choat et al. 2003) | Choat B, Ball M, Luly J, Holtum J; Plant Physiol 131:41-48 (2003); title matches; DOI MATCH.
- WRONG | [cite-zhang] S. Zhang et al., "High porosity with tiny pore constrictions and unbending pathways characterize the 3D structure of intervessel pit membranes in angiosperm xylem," Plant, Cell & Environment (2020) | https://oparu.uni-ulm.de/server/api/core/bitstreams/a0bedabe-c04f-494a-8970-ee5236f07c99/content (Zhang et al. 2020 PDF, read with pdftotext); Europe PMC record doi 10.1111/pce.13654 | The PDF's byline starts "Ya Zhang1,2 / Cora Carmesin1 ...", ORCID "Ya Zhang"; Europe PMC "Zhang Y". The page gives "S. Zhang et al." (S. is the last author, Steven Jansen). Title and journal match; volume 43:116-130.
- CONFIRMED | [cite-choat2008] Choat, Cobb & Jansen, "Structure and function of bordered pits," New Phytologist (2008) | https://www.ebi.ac.uk/europepmc/webservices/rest/search?query=EXT_ID:18086228%20AND%20SRC:MED&format=json&resultType=core | Choat B, Cobb AR, Jansen S; New Phytol 177:608-626 (2008); the page drops the subtitle after the colon.
- UNVERIFIABLE | [pore-5-20-choat2008] We can source mean pit-membrane pore diameters of 5 to 20 nm to Choat, Cobb and Jansen (2008). | Choat, Cobb & Jansen 2008: Europe PMC abstract; Wiley full text and PDF (HTTP 403 by curl and WebFetch); Wayback (no snapshot); OpenAlex (closed) | The 2008 abstract gives no pore diameters. Positive control: the same curl setup read the Choat 2003 PMC text and the Zhang PDF. The 5 to 20 nm figure is in Choat et al. 2003 ("pit membrane pores were between 5 and 20 nm in diameter"); whether the 2008 review repeats it, and calls it a mean, is unread.
- UNVERIFIABLE | [pore-5-20-choat2003] Choat, Cobb and Jansen (2008) report mean pit-membrane pore diameters of about 5 to 20 nm from colloidal gold perfusion. | https://pmc.ncbi.nlm.nih.gov/articles/PMC166785/ (Choat et al. 2003); Choat 2008 unreadable (see above) | Same claim as above. The record's excerpt is from the 2003 paper, which says "between 5 and 20 nm", not "mean"; it does not show what the 2008 review the page names reports.
- CONFIRMED | [cite-choat2012] B. Choat et al., "Global convergence in the vulnerability of forests to drought," Nature 491:752–755 (2012) | https://repository.naturalis.nl/document/495587 (Choat et al. 2012 PDF) and Europe PMC abstract, doi 10.1038/nature11688 | Nature 491:752-755 (2012), title matches; DOI MATCH.
- CONFIRMED | [cite-tr] J. M. Torres-Ruiz & H. Cochard et al., "Xylem resistance to embolism: presenting a simple diagnostic test for the open vessel artefact," New Phytologist 215:489–499 (2017) | https://www.ebi.ac.uk/europepmc/webservices/rest/search?query=EXT_ID:28467616%20AND%20SRC:MED&format=json&resultType=core | Torres-Ruiz JM, Cochard H, Choat B et al. (13 authors); New Phytol 215:489-499 (2017).
- CONFIRMED | [cite-lopez] R. Lopez, M. Nolf, R. A. Duursma, E. Badel, R. J. Flavel, H. Cochard & B. Choat, "Mitigating the open vessel artefact in centrifuge-based measurement of embolism resistance," Tree Physiology 39(1):143–155 (2019) | https://www.ebi.ac.uk/europepmc/webservices/rest/search?query=EXT_ID:30085232%20AND%20SRC:MED&format=json&resultType=core | López R, Nolf M, Duursma RA, Badel E, Flavel RJ, Cochard H, Choat B; Tree Physiol 39:143-155 (2019).
- CONFIRMED | [cite-sperry] Sperry et al., "Vulnerability curves by centrifugation: is there an open vessel artefact, and are 'r' shaped curves necessarily invalid?" Plant, Cell & Environment 35 (2012) | https://www.ebi.ac.uk/europepmc/webservices/rest/search?query=EXT_ID:21988455%20AND%20SRC:MED&format=json&resultType=core | Title matches; Plant Cell Environ 35:601-610 (2012 issue).
- CONFIRMED | [cite-venturas] Venturas et al., Plant, Cell & Environment 42 (2019). | https://www.ebi.ac.uk/europepmc/webservices/rest/search?query=EXT_ID:30997689%20AND%20SRC:MED&format=json&resultType=core | Plant Cell Environ 42:2422-2436 (2019).
- CONFIRMED | [cite-wei1999] C. Wei, M. T. Tyree & E. Steudle, Plant Physiology 121:1191–1206 (1999) | https://www.ebi.ac.uk/europepmc/webservices/rest/search?query=DOI:%2210.1104/pp.121.4.1191%22&format=json&resultType=lite | "Wei C, Tyree MT, Steudle E", Plant Physiol 121:1191-1206 (1999). The tool's 47% title-word mismatch only reflects that the page gives no title.
- CONFIRMED | [cite-wei2001] Wei et al., Plant, Cell & Environment (2001). | https://api.crossref.org/works/10.1046/j.1365-3040.2001.00697.x | "The essentials of direct xylem pressure measurement", Wei, Steudle, Tyree, Lintilhac; PCE 24:549-555 (2001).
- CONFIRMED | [cite-pammenter] N. W. Pammenter & C. Vander Willigen, Tree Physiology 18 (1998). | https://api.crossref.org/works/10.1093/treephys/18.8-9.589 | Tree Physiol 18:589-593 (1998). Crossref spells "Van der Willigen"; Choat 2003 cites "Vander Willigen", as the page does.
- OBSERVED | [placard-written] Last verified 20 July 2026, when it was written. | src/content/strata/water-under-tension.md at 685fdbaa44 (date: 2026-07-20T04:00:00Z); git log: layer born b03ce7088d1 2026-07-20 | The layer was written 2026-07-20 and nothing at the pin records a later verification (no assay record for the slug).
- OBSERVED | [placard-emptied] Measured: with every file this layer ships emptied, it still passes. | recreated: the verifier opens no file (no fs import, no readFile) and passed alone in an empty directory, "ALL 68 CHECKS PASSED" | Emptying the layer's other files cannot change it; matches the placard.
- CONFIRMED | [maxima-200nm] quoted maxima run to a couple of hundred nanometres across the literature | https://pmc.ncbi.nlm.nih.gov/articles/PMC166785/ (Choat et al. 2003) | One calculated maximum: "Values given in Table III should be characteristic of maximum pit membrane pore diameters ... 200 nm for C. gillivraei". "across the literature" rests on this one paper; the page says it is not a sourced bound.
- MINOR | [one-length-scale] one length scale predicts the species | https://pmc.ncbi.nlm.nih.gov/articles/PMC166785/ (Choat et al. 2003); https://oparu.uni-ulm.de/server/api/core/bitstreams/a0bedabe-c04f-494a-8970-ee5236f07c99/content (Zhang et al. 2020 PDF, read with pdftotext) | The paper the page leans on found the opposite of a prediction: "the results of the present study did not confirm the existence of pores above 20 nm in diameter in pit membranes or the expected inter-specific variation in pore size"; Zhang 2020: the small constrictions "raise questions about the classic air-seeding mechanism". The page's own round-trip box concedes this, but this sentence and the strata note ("so one length scale predicts a species") state it as established.
- UNVERIFIABLE | [pore-dominant-term] That is why pore structure is the dominant term in embolism resistance | https://repository.naturalis.nl/document/495587 (Choat et al. 2012 PDF) and Europe PMC abstract, doi 10.1038/nature11688; https://pmc.ncbi.nlm.nih.gov/articles/PMC166785/ (Choat et al. 2003); https://oparu.uni-ulm.de/server/api/core/bitstreams/a0bedabe-c04f-494a-8970-ee5236f07c99/content (Zhang et al. 2020 PDF, read with pdftotext) | Nearest: Choat 2012, embolism resistance "is largely determined by differences in the structure of the xylem" (xylem structure, not pore size). Choat 2003 and Zhang 2020 (above) cut against pore size as the dominant term.
- UNVERIFIABLE | [desert-willow] a desert shrub and a streamside willow, made of much the same water, part company by a factor of ten | Pockman & Sperry 2000 abstract; Maherali 2004 abstract | Pockman & Sperry compare riparian Salix gooddingii with upland desert shrubs (Larrea tridentata) and find upland species "uniformly less vulnerable to cavitation", but the abstract gives no P50 values, so "a factor of ten" is not shown.
- CONFIRMED | [centrifuge-much-data] much of the world's embolism data comes from a centrifuge method | https://www.ebi.ac.uk/europepmc/webservices/rest/search?query=EXT_ID:28467616%20AND%20SRC:MED&format=json&resultType=core; Cochard 2013 abstract | "The standard centrifuge technique is widely used"; Cochard 2013: centrifugation-PLC and Cavitron are two of the four methods behind "more than 96% of all curves".
- MINOR | (added) "Choat, Cobb and Jansen (2008) report mean pit-membrane pore diameters of about 5 to 20 nm from colloidal gold perfusion. The rare wider pores that actually set the air-seeding threshold are not resolved by that method" | https://pmc.ncbi.nlm.nih.gov/articles/PMC166785/ (Choat et al. 2003); https://oparu.uni-ulm.de/server/api/core/bitstreams/a0bedabe-c04f-494a-8970-ee5236f07c99/content (Zhang et al. 2020 PDF, read with pdftotext) | States as fact one of the hypotheses: Choat 2003 offers "(b) larger pores ... were present but were rare enough to avoid detection" as one of three possibilities, and Zhang 2020 says "enlarged pores are typically not observed" and "the artifactual pores observed under SEM should be discounted as evidence for rare, large pores".
- MINOR | (added) "Zhang and colleagues (2020) read the gap between the 7.2 MPa a 20 nm pore should hold in pure water and the far weaker pressures at which plants actually fail as evidence that sap surfactants lower γ." | https://oparu.uni-ulm.de/server/api/core/bitstreams/a0bedabe-c04f-494a-8970-ee5236f07c99/content (Zhang et al. 2020 PDF, read with pdftotext) | Zhang argues the other way round: surfactants "are known to occur in xylem sap" (independent evidence), so γ is "likely to be much reduced"; even then (2.4 MPa) "most species" fail at lower pressure differences, which "raise[s] questions about the classic air-seeding mechanism". The gap is not read as evidence for surfactants.
- MINOR | (added) dek: "a species with a 0.77 MPa safety margin be reported as already dead"; panel: "true margin is +0.77 MPa"; slider "Ψmin the plant actually reaches: –2.40 MPa" | https://pmc.ncbi.nlm.nih.gov/articles/PMC166785/ (Choat et al. 2003) (searched for a field minimum water potential: none; terms "−2.4", "midday", "predawn", "minimum water potential" 0 hits, positive control "−3.17" found) | The 0.77 MPa is the B. australis P50 (−3.17, sourced) minus a Ψmin of −2.40 that no source gives for that species; Choat 2003 reports no field minimum. The Ψmin default is a free choice, but it is missing from "Every free choice on this page, named", and the dek calls the result a species' margin.

## Findings
- [fixed] theta-larger-pore (WRONG): the contact-angle item said a non-zero angle makes every inferred pore larger; under the page's D = 4γcosθ/|P50| it makes them smaller. Now "smaller", with the reason; the README's copy fixed too. Corrected line added.
- [fixed] wei-probe-limit (WRONG): "the probe's own apparatus could not record below about −0.65 MPa" replaced by what Wei, Tyree and Steudle 1999 report: their oil-filled cell pressure probe should be safe to about −1 MPa, and water-filled probes cavitated at −0.6 to −0.7 MPa; the 0 to −0.7 MPa range of agreement (abstract) kept. README copy fixed. Corrected line added.
- [fixed] checks-66-dek (WRONG): the dek's "66 offline checks." is now 68. One Corrected line covers this and checks-66-body.
- [fixed] checks-66-body (WRONG): the markdown source note's "66 offline checks" is now 68, and so are the README and the index.html header comment.
- [fixed] hyperion-p-abs (WRONG): "Ψ = −1.03 MPa, which is what gravity alone demands at the top of Hyperion" now gives Ψ = −1.13 MPa and names −1.03 MPa as the absolute pressure. Corrected line added.
- [fixed] cite-zhang (WRONG): "S. Zhang et al." is now "Y. Zhang et al." (Crossref: Ya Zhang). Corrected line added.
- [fixed] ceiling-10-33 (MINOR): vapour pressure (2.34 kPa at 20 °C, about 24 cm, so about 10.11 m) is now named among the free choices; the 10.33 m stays as the page's stated ideal.
- [fixed] atm-defn (MINOR): "is defined as" now "was originally defined as".
- [fixed] cap-three-orders (MINOR): "three orders of magnitude" now "one and a half to three orders of magnitude" (39× to 780× against the 128 nm Hyperion would need).
- [fixed] choat2003-no-see (MINOR): the sentence now separates SEM (nothing visible to 20 nm) from gold perfusion (pores of 5 to 20 nm in all four species, smaller than predicted); the README's copy fixed too.
- [fixed] zhang-surfactants (MINOR): "they attribute the gap to surface-active substances" now says Zhang 2020 expect sap surfactants to lower γ but that even the lipid value (2.4 MPa) leaves most species failing sooner, which they read as a question for classic air seeding; the README's copy fixed too.
- [fixed] added Zhang line (MINOR): the disputed-list sentence ("read the gap ... as evidence that sap surfactants lower γ") now says the same: surfactants probably lower γ, the 2.4 MPa lipid value still leaves most species failing sooner, and Zhang read that as a question for the classic air-seeding mechanism.
- [fixed] choat2012-rainforest-desert (MINOR): "as deserts" now "as the driest forests and woodlands".
- [fixed] p50-range (MINOR): "roughly –0.5 to –14 MPa" now "roughly –0.2 to –14 MPa" (Maherali et al. 2004: −0.18 to −14.1).
- [fixed] nothing-stored (MINOR): the check panel, header comment and README now say no readout is stored and the prose figures are typed and checked offline, except the vapour-pressure figures, which are worked by hand and say so.
- [fixed] one-length-scale (MINOR): page and strata note now frame it as the air-seeding account's claim.
- [fixed] added rare-pores line (MINOR): now attributed to the rare-pit hypothesis rather than stated as fact.
- [fixed] added margin line (MINOR): Ψmin = −2.40 MPa is now named among the free choices as ours, not a measurement, and the dek calls the 0.77 MPa margin illustrative.