Vasicentric Tracheids as a Drought Survival Mechanism in the Woody Flora of Southern California and Similar Regions; Review of Vasicentric Tracheids
Vasicentric Tracheids as a Drought Survival Mechanism in the Woody Flora of Southern California and Similar Regions; Review of Vasicentric Tracheids
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作为南加州和类似地区木本植物区系的干旱生存机制的Vasicentric管胞；
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发表时间：
1985
期刊：
影响因子：
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通讯作者：
Deng Pan
中科院分区：
文献类型：
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作者：
Xuanming Xu;Lian Tang;Yang Yu;Jiayou Zhang;Xiaoyan Zhou;Tingting Zhou;Chao Xuan;Qingwu Tian;Deng Pan
Vasicentric管胞被定义为在木材中存在于血管附近的管胞，该管胞也具有libriform纤维或纤维管胞作为不穿孔的管胞元件。维管状管胞体符合这一定义，但被定义为只出现在晚木中，而维管心管胞则出现在整个生长期或扩散多孔树种的木材中。当血管因空气栓塞而失效时，无心管胞提供辅助的传导系统，为茎和叶供血。真正的管胞（在它们生长的树林中作为唯一的无孔管胞元素类型存在）具有大致相同的生理作用，最大限度地提高了传导的潜在安全性。Vasicentric管状体、维管状管状体和真管状体的相似之处在于，它们都是不穿孔的管状体，具有相对较大的边缘凹点，其密度近似于血管侧壁上的凹点。在有维管状管胞或维管状管胞的树木中也有Libriform纤维或纤维管胞。维管管，由于只出现在生长环的末端（在那里它们演变成狭窄的导管元件），维持茎中的水柱，从而在干旱季节持续存在，但可能不能充分供应叶子，叶子可能随着干旱的进展而枯萎。维实心管胞通过保护生长期各部分的传导，似乎与许多具有维实心管胞的灌木所具有的常绿习性有关。具有真管胞的门类在双子叶植物中相对较少，而且这些类群中只有一小部分明显地成功地适应了干燥气候。许多门类通过进化出血管中心管胞而具有libriform纤维或纤维管胞，从而具有相当的安全性。因此，在地中海型常绿耐旱灌木适应的地区，具有维管心管胞的属在植物区系中占很大的比例。在南加州，26个家庭（17个为首次报道）有输精管心性；值得注意的属包括熊葡萄属、海芋属、李属、栎属和鼠尾草属。沙漠灌木有维囊心管胞到稍小的程度。对其他地中海型地区进行了vascentric管胞和真管胞的调查。这样分析的地区是智利中部、澳大利亚南部、地中海附近的土地和非洲南部。在这些地区具有输精管胞的属包括Banksia、Carissa、Eucalyptus、Grevil/ea、Hakea、Protea、Quercus、rosemary等。新西兰和日本比较湿润，有维丝心管胞的属较少，但有真管胞的属较多。许多耐旱的常绿灌木有维细心管胞。为世界植物区系提供了一份新的有输精管胞的科和属的目录，并记录了新的报告和相关文献。新收录68科（其中33科为新收录），较Metcalfe和Chalk在1950年和1983年的目录中收录的32科有了长足的进步，并首次收录了一些大而多样的科（如Ericaceae、Pittosporaceae、Rosaceae）。缺乏关于血管中心管胞发生的报道可能部分与难以识别这些细胞有关；提出了分析建议。
Vasicentric tracheids are defined as tracheids present adjacent to vessels in a wood which also possesses libriform fibers or fiber-tracheids as imperforate tracheary elements. Vasculartracheids would correspond with this definition, but are defined as occurring only in latewood, whereas vasicentric tracheids occur throughout a growth ring or in wood of a diffuse-porous species. V asicentric tracheids offer a subsidiary conducting system which can supply stems and leaves when the vessels to which vasicentric tracheids are adjacent fail because of air embolisms. True tracheids (present as the sole imperforate tracheary element type in the woods in which they occur) have much the same physiological effect, maximizing potential safety in conduction. Vasicentric tracheids, vascular tracheids, and true tracheids are alike in being imperforate tracheary elements bearing relatively large bordered pits approximately like those on lateral walls of vessels in density. Libriform fibers or fiber-tracheids also occur in woods in which vasicentric tracheids or vascular tracheids are present. Vascular tracheids, by virtue of occurrence only at the end of a growth ring (where they grade into narrow vessel elements), maintain water columns in stems, which thereby persist through dry seasons, but may not adequately supply leaves, which may wilt as drought progresses. Vasicentric tracheids, by safeguarding the conduction of all parts of a growth ring, seem related to the evergreen habit which many shrubs possessing vasicentric tracheids have. Phylads with true tracheids are relatively few in dicotyledons, and only a small part ofthese groups have evidently succeeded in adapting to dry climates. The numerous phylads which instead have libriform fibers or fiber-tracheids have developed comparable safety by evolving vasicentric tracheids. Therefore genera with vasicentric tracheids bulk large in the floras of areas in which evergreen drought-tolerant shrubs are adaptive, the Mediterranean-type areas of the world. In southern California, 26 families (17 reported for the first time) have vasicentric tracheids; notable genera include Arctostaphylos, Ceanothus, Prunus, Quercus, and Salvia. Desert shrubs have vasicentric tracheids to a somewhat lesser degree. Other Mediterranean-type areas are surveyed for both vasicentric tracheids and true tracheids. The regions so analyzed are central Chile, southern Australia, the lands adjacent to the Mediterranean Sea, and southern Mrica. Genera in these areas with vasicentric tracheids include Banksia, Carissa, Eucalyptus, Grevil/ea, Hakea, Protea, Quercus, Rosmarinus, etc. New Zealand and Japan are wetter and have fewer genera with vasicentric tracheids but more with true tracheids. Many drought-tolerant evergreen shrubs have vasicentric tracheids. A new listing of families and genera with vasicentric tracheids is provided for the world flora, with new reports documented and pertinent literature cited. This new listing includes 68 families (33 newly reported in this paper), which represents a considerable advance on the 32 families listed by Metcalfe and Chalk in their compendia of 1950 and 1983, and includes some large and diverse families for the first time (e.g., Ericaceae, Pittosporaceae, Rosaceae). The lack of reports on occurrence of vasicentric tracheids may in part relate to difficulty in identifying these cells; suggestions for analysis are given.