Evolution and palaeophysiology of the vascular system and other means of long-distance transport

摘要: Photolithotrophic growth on land using atmospheric CO2 inevitably involves H2O vapour loss. Embryophytes greater than or equal to 100 mm tall are homoiohydric and endohydric with mass flow of aqueous solution through the xylem in tracheophytes. Structural details Rhynie sporophytes enable modelling hydraulics supply transpiring surface, potential for gas exchange Devonian atmosphere. Xylem carrying under tension programmed cell death, rigid walls embolism repair; fossils provide little evidence these functions other presence lignin. The phenylalanine ammonia lyase essential lignin synthesis came from horizontal gene transfer. plants lack endodermes, limiting regulation soil nutrients shoots. transfer organic solutes photosynthetic sites growing storage tissues phloem extant show phloem; possible alternatives transport discussed. Extant examples arbuscular mycorrhizas found soil-derived (especially P) plant-derived matter, involving bidirectional along hyphae. aquatic cyanobacteria charalean Palaeonitella at also have long-distance (relative size organism) transport.This article is part a discussion meeting issue 'The cherts: our earliest terrestrial ecosystem revisited'.