Westman Walter E
Department of Geography, University of California, Los Angeles, 90024, Los Angeles, California, USA.
Oecologia. 1981 Jan;51(3):385-388. doi: 10.1007/BF00540910.
A pattern of seasonal variation in leaf size and position relative to the stem is reported for twelve mesophyllous shrubs in the coastal sage scrub of Mediterranean-climate areas of southern California. Leaves of reduced size, produced on axillary short shoots late in the growing season, persist through the dry season while many of the larger leaves on main stems are abscissed. The short-shoot leaves of Salivia mellifera have the same density thickness as those of the main stem, leaving open the question of whether the smaller summer leaves have physiological mechanisms for drought tolerance beyond a reduction in total transpiring surface. In Californian coastal shrublands seasonal dimorphism of leaves appears limited to mesophyllous shrubs. It is also found in analogues in comparable climatic regions of the Mediterranean, Chile and South Africa.
据报道，在南加州地中海气候区沿海鼠尾草灌丛中的12种叶肉灌木，叶片大小和相对于茎的位置存在季节性变化模式。在生长季节后期，腋生短枝上长出的小叶会持续整个旱季，而主茎上的许多大叶则会脱落。蜜花鼠尾草的短枝叶与主茎叶具有相同的密度厚度，这就引发了一个问题：较小的夏季叶片除了减少总蒸腾面积外，是否还具有耐旱的生理机制。在加利福尼亚沿海灌木丛中，叶片的季节性二态性似乎仅限于叶肉灌木。在地中海、智利和南非等气候相似地区的类似植物中也有发现。
