拐枣果序梗的发育解剖学研究

DEVELOPMENTAL ANATOMY OF PEDUNCLE IN HOVENIA DULCIS THUNB.

拐枣肉质膨大果序梗的发育过程可划分为前、中、后、未４个时期。前期为初生生长时期，内部结构类似一般双子叶植物茎的初生构造；中期为维管形成层活动时期，产生了不同于其茎的次生木质部，由成片未木质化的厚壁纤维细胞、一定量的木射线及星散在其中极少数的导管组成；后期为异常分生组织活动时期，初生木质部木薄壁组织及邻近少量髓细胞转化为异常分生组织，向外产生切向排列的薄壁细胞，经扩大和切向伸长，使原导管间的距离增大，有些直接与皮层薄壁细胞相通，组成了新的束间区。向内产生新的薄壁细胞添加到髓中。这种现象从未见过报道。末期，维管组织极度退化。中期以后直至成熟，皮层和髓细胞强烈扩大、径向伸长。

The develpmental process of fleshy and accrescent peduncle in Hovenia dulcis Thunb.maybe divided into four stages. The early stage is a primary growth stage. The inner structure in pe-duncle is similar to the primary structure in stem of dicotyledons at this stage. At the middlestage , vascular cambium cells division fast,and the primary xylem consistes of many fibre cellswhich are not lignified and some xylem rays as well as a few of vessels. At the late stage,parenchyma in primary xylex and a few of pith cells turn into anomalous meristem. The anoma-lous meristem produces new parenchyma cells to pith. The tangential parenchyma cells that areproduced by the anomalous meristem expand and enlarge the distance between vessels,and someof parenchyma cells expend so strong that they reach cortex and make new interfascicular re-gions. This phenomenon has never been reported yet. At the final stage,vascular tissue degener-ates highly. The expansion and radial spread of cortex and pith cells are very strong after the mid-dle stage.