Abscission of Marcescent Leaves of Quercus palustris and Q. coccinea
Abscission of Marcescent Leaves of Quercus palustris and Q. coccinea
复制标题
沼泽栎和红栎的残渣叶脱落
作者：
R. W. Hoshaw;A. T. Guard
1.沼泽栎和栎的叶柄基部没有明显的分离带。球菌属。基底细胞在组织学上似乎与邻近组织的细胞相同。2.伴随着脱落的过程被发现在一个枯萎的叶子的叶柄基部的活组织的绿色区域内起作用;叶柄的其余部分和叶片是死的。3.叶柄基部有一层由4 ~ 12层细胞组成的木质层。这层脂化层是在1月初在Q. 6-7周后，Q.沼泽4.分离层位于木质化层下方一到两个细胞，包括四到五层细胞。5.分离过程包括一些细胞沿着中层平面分离，而另一些细胞通过与中层成直角的细胞壁被动破裂而分离。6.在分离过程中没有观察到细胞分裂。7.在最后一片叶子脱落的过程中，分离层的细胞壁塌陷，使叶柄容易分离。第一片叶子由于机械力，如风和叶片和叶柄的重量而落下。8.两种Q. palustris和Q.在相对较短的时间内发生霍乱。Q.落叶病球虫的生长比Q.沼泽9.在所有检查的材料中均存在草酸钙晶体。这些晶体似乎分布在所有组织中，包括分离层中的组织。10. Q.由于叶柄的断裂，球菌脱落。Q的一些叶子。沼泽地也因叶柄断裂而倒下。当花蕾膨胀时，叶柄残端脱落。
1. There is no well-defined separation zone at the base of the petiole in either Quercus palustris or Q. coccinea. The cells of the base appear to be histologically the same as those of adjacent tissues. 2. The processes accompanying abscission are found to function within a greenish area of living tissue at the base of the petiole of a marcescent leaf; the remainder of the petiole and the blade are dead. 3. A lignified layer consisting of from four to twelve tiers of cells forms in the petiole base. This lignified layer was observed early in January in Q. coccinea and 6-7 weeks later in Q. palustris. 4. The separation layer is located one to two cells below the lignified layer and includes four to five tiers of cells. 5. The process of abscission involves the separation of some cells along the plane of the middle lamellae, while other cells separate by a passive breaking of the cell walls at right angles to the middle lamellae. 6. No cell division was observed during the abscission process. 7. During the abscission of the last leaves to fall the cell walls of the separation layer collapse, allowing the petiole to separate easily. The first leaves drop as a result of mechanical forces, such as wind and the weight of the blade and petiole. 8. The greater portion of leaves of both Q. palustris and Q. coccinea abscise over a relatively short period of time. Leaf-fall in Q. coccinea was more rapid and uniform than in Q. palustris. 9. Crystals of calcium oxalate were present in all the material examined. These crystals appeared to be distributed through all tissues, including those in the separation layer. 10. A high percentage of the leaves of Q. coccinea dropped as a result of the breaking of the petiole. Some leaves of Q. palustris also fell as a result of broken petioles. The petiole stubs dropped when the buds swelled.