DISSERTATION RESEARCH: Plant Water Relations and the Ecology of the Primitive Angiosperm Family Winteraceae

冬青科被认为是开花植物中最古老和最原始的家族之一。这65种植物缺乏木质部导管，木质部导管被认为是被子植物实现其目前的生态优势的关键适应。冬虫夏科一直被视为“活化石”，它们生活在潮湿的森林地带，在那里它们以管胞为基础的木材不会施加水力限制。然而，系统发育分析表明，现存被子植物的共同祖先有维管，而这些维管在冬虫夏科中消失了。对冬青科水力学的初步研究表明，无容器木材不会造成水力约束。小木质部导管，如那些在针叶树和冬青科中发现的导管，可能为经历冻融循环的常绿木本植物提供功能优势。这一假设将使用塔斯马尼亚亚高山雨林和新喀里多尼亚热带山地森林中十种冬青科植物的水分平衡生理数据进行验证，并与有和没有导管的共生树木进行比较。

The Winteraceae are regarded as among the oldest and most primitive families of flowering plants. These ~65 species lack xylem vessels, which are thought to be a critical adaptation permitting angiosperms to achieve their current ecological domination. The Winteraceae have been viewed as 'living fossils' that survive in wet forest pockets where their tracheid-based wood does not impose hydraulic constraints. However, phylogenetic analysis implies that the common ancestor of extant angiosperms had vessels and that these were lost in Winteraceae. Preliminary studies on Winteraceae hydraulics indicate that vessel-less wood does not impose a hydraulic constraint. Small xylem conduits, such as those found in conifers and the Winteraceae, may confer a functional advantage for evergreen woody plants experiencing freeze-thaw cycles. This hypothesis will be examined using physiological data on the water balance of ten Winteraceae species in the sub-alpine rainforest of Tasmania and tropical montane forests of New Caledonia compared to co-occurring trees with and without vessels.