A stem-sized surprise Along the smooth, jointed stem of a modern horsetail plant, water rises from the base and grows progressively stranger in its oxygen makeup.<\/p>\n By sampling water from the bottom to the tip, Zachary Sharp, Ph.D., at the University of New Mexico<\/a> demonstrated that the stem itself steadily concentrates heavy oxygen as moisture escapes into dry air.<\/p>\n Values that began within a typical natural range at the base climbed to levels so enriched at the tip that they exceeded every prior terrestrial measurement.<\/p>\n Because that chemical transformation unfolds inside a single plant rather than in an extreme environment, the finding demands a closer look at how evaporation reshapes water long before it reaches a leaf.<\/p>\n Evaporation up the stem<\/p>\n Evaporation<\/a> kept pulling water out of the stem as it rose, even before reaching any leafy branches.<\/p>\n As droplets escaped through the stem wall, lighter water molecules left first, so heavier oxygen<\/a> stayed behind.<\/p>\n Each higher segment started with already-enriched water, then lost more to air, building an extreme gradient toward the tip.<\/p>\n Dry wind and heat can push that process harder, which helps explain odd oxygen data from desert plants.<\/p>\n Oxygen atoms as clues<\/p>\n Oxygen in water carries a chemical signature that scientists use to track where moisture came from and what happened next.<\/p>\n A water sample holds more than one kind of oxygen, and isotopes \u2013 atoms of one element with different weights \u2013 mark that mix.<\/p>\n When water dries, molecules with lighter oxygen escape first, and the leftover liquid keeps heavier oxygen through evaporation.<\/p>\n Without careful interpretation, that simple sorting can make a lake, a leaf, or a fossil look wetter or drier than it was.<\/p>\n Three oxygen signals<\/p>\n Three separate oxygen versions in the same water drop let scientists tell whether evaporation or source water drove a change.<\/p>\n Sharp\u2019s group tracked three versions<\/a> of oxygen at once, following how each one changed together in the water moving through the stem.<\/p>\n That extra layer matters because heavy oxygen is rare, and small biases can hide when only one ratio is measured.<\/p>\n With three signals at once, the team could test plant-water models in a way ordinary measurements cannot.<\/p>\n Beyond Earth\u2019s range<\/p>\n Horsetails have a fossil record reaching to the Devonian, a period about 400 million years ago, which defines their long lin<\/a>eage<\/a>.<\/p>\n In smooth horsetail stem water, the share of heavier oxygen climbed sharply from the base to the tip, reaching levels no one had measured before in a living plant.<\/p>\n \u201cIf I found this sample, I would say this is from a meteorite,\u201d said Sharp.<\/p>\n By stretching the known oxygen range across Earth and the solar system fivefold, the results gave modelers a hard boundary.<\/p>\n Trapped water chemistry<\/p>\n Inside horsetail tissues, silica builds tiny glassy bodies that can survive long after the plant dies.<\/p>\n Researchers call these bodies phytoliths<\/a>, tiny silica casts formed inside plants, and horsetails rank among the highest silica accumulators.<\/p>\n In Sharp\u2019s data, the oxygen fingerprint in phytolith silica did not match the water moving through the stem.<\/p>\n That mismatch means fossil phytolith readings can point to the wrong humidity story, especially when researchers average the whole stem<\/a>.<\/p>\n Fixing model assumptions<\/p>\n Models that predict plant<\/a> water chemistry depend on a few constants, and one of them had been slightly off.<\/p>\n Using measurements from the entire stem, Sharp\u2019s team adjusted a key number in evaporation models so it better matches how water vapor actually moves through dry air.<\/p>\n That updated number helped explain earlier puzzling oxygen readings in desert plants and animals that drink from strongly evaporated water.<\/p>\n Better constants will not fix every uncertainty, but they reduce the risk of blaming biology when physics drove the signal.<\/p>\n Fossils meet dry air<\/p>\n Scientists have tested<\/a> fossil phytolith oxygen signals as a way to estimate past humidity.<\/p>\n Since moisture in the air affects how quickly water escapes from plants, the oxygen pattern left behind can reflect how dry the air was.<\/p>\n \u201cWe can now begin to reconstruct the humidity and climate conditions of environments going back to when dinosaurs roamed the Earth,\u201d said Sharp.<\/p>\n Still, Sharp\u2019s warning about mismatched phytolith signals sets limits on what those fossils can tell without extra context.<\/p>\n Horsetails, water, and oxygen isotopes<\/p>\n A summer course helped make the work possible, mixing field sampling with lab runs that trained students on real data.<\/p>\n Through a summer lab-field class, 14 students helped collect stems and measure oxygen fingerprints at UNM facilities.<\/p>\n Back in Albuquerque, New Mexico, the Center for Stable Isotopes ran the samples, and electron microscopes checked the silica growing in stems.<\/p>\n That hands-on path matters, because climate tools improve fastest when students and senior scientists test them against messy nature.<\/p>\n Extreme water fingerprints from a living horsetail give scientists a new way to stress-test climate models and fossil proxies.<\/p>\n Future work will need to map similar signals in other plants and environments, especially where drought pushes evaporation to the limit.<\/p>\n The study is published in Proceedings of the National Academy of Sciences<\/a>.<\/p>\n \u2014\u2013<\/p>\n Like what you read? Subscribe to our newsletter<\/a> for engaging articles, exclusive content, and the latest updates.<\/p>\n Check us out on EarthSnap<\/a>, a free app brought to you by Eric Ralls<\/a> and Earth.com.<\/p>\n \u2014\u2013<\/p>\n","protected":false},"excerpt":{"rendered":"Water drawn through the hollow stem of a living Equisetum plant, called horsetail, has registered the most extreme…\n","protected":false},"author":2,"featured_media":351623,"comment_status":"","ping_status":"","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[7],"tags":[61,60,82],"class_list":["post-457420","post","type-post","status-publish","format-standard","has-post-thumbnail","category-science","tag-ie","tag-ireland","tag-science"],"_links":{"self":[{"href":"https:\/\/www.newsbeep.com\/ie\/wp-json\/wp\/v2\/posts\/457420","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/www.newsbeep.com\/ie\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/www.newsbeep.com\/ie\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/www.newsbeep.com\/ie\/wp-json\/wp\/v2\/users\/2"}],"replies":[{"embeddable":true,"href":"https:\/\/www.newsbeep.com\/ie\/wp-json\/wp\/v2\/comments?post=457420"}],"version-history":[{"count":0,"href":"https:\/\/www.newsbeep.com\/ie\/wp-json\/wp\/v2\/posts\/457420\/revisions"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/www.newsbeep.com\/ie\/wp-json\/wp\/v2\/media\/351623"}],"wp:attachment":[{"href":"https:\/\/www.newsbeep.com\/ie\/wp-json\/wp\/v2\/media?parent=457420"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.newsbeep.com\/ie\/wp-json\/wp\/v2\/categories?post=457420"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.newsbeep.com\/ie\/wp-json\/wp\/v2\/tags?post=457420"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}
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