摘要
根冠由数层细胞组成,它重叠成帽状包围于根端的分生区之外,根表皮层全为薄壁细胞,无根毛。皮层由数层薄壁细胞组成,中柱鞘为单层细胞,紧靠于内皮层之内。内皮层凯氏带明显,初生根具4原型原生中柱。初生韧皮部与初生木质部束相间排列。茎表皮朝外一面角质化,表皮上发育有气孔。表皮层之下有多层绿色组织细胞。它们较更内层的细胞为小。维管束为外韧形,排成环状,维管束间有薄壁细胞分隔,它们在个体发育中增厚。髓由薄壁细胞组成,成熟时由于细胞的破坏而中空。叶柄中有5个维管束,每一维管束由薄壁细胞分隔开来。叶片表皮中有花青素,叶肉中只有一层栅栏组织细胞,海绵薄壁细胞则有数层。下表皮上气孔的数量比上表皮为少。
The root cap consists of Several layers of cells which form a series of overlapping conessurrounding the mesistematic region of the root tip.The epidermal cells of the root are also thin—wall,which have no root hairs.The cortex of the young root is comprised of a few layers ofparenchymatous cells.The pericycle consists of a single layer of cells lying immediately within theendodermis in which casparian thickenings are evident.The primary root has a tetrach protostele.Thegroups of primary phloem alternate with the points of proxylem.The epidermis of the stem may be cutinized on their outer surface.The stomata are developed onthe epidermis.Underlying,the epidermal layer there are several layers of chlorenchymatous cells whichare small than the inner layersof the cortex.The vascular bundles are collateral and forma a dissectedsiphonostele.Adjacent bundles are separated by the parenchymatous cells.Later in ontogeny the wallsthicken.The pith consists of parenchymatous cells,which are commonly hollow at maturity owing tothe distintegration of the cells.The vascular of the petiole consists of five collated bundles.Each bundle is separated fromparenchymatous cells.Anthocyanin may occur in the cells of the epidermal layer of the blade.The mesophyll consists ofa single—layered of palisade cells.The spongy parenchyma which is several cells in thickness.Thestomata are more abundant in thr upper than the lower epidermis.
出处
《南京师大学报（自然科学版）》
CAS
CSCD
1993年第1期44-49,86,共7页
Journal of Nanjing Normal University(Natural Science Edition)
关键词
豆瓣菜
营养器官
解剖
Anatomy
Vegetative organ
Nasturtium officinale
