薯蓣零余子发育与形态学本质探讨

薯蓣零余子的原基起源于叶腋表层1～3层细胞。初期,原基细细胞团分化为内外两部分组织:外侧为薄壁组织及紧邻其内的囊状初生加厚分生组织,内侧为薄壁组织。初生加厚分生组织主要向内衍生细胞,它们分化为薄壁组织和散生其中的有限外韧维管束。零余子的外形多样,常呈块状,无节,基部有1～3个不定芽。从零余子原基外起源、幼期与叶芽间存在过渡型、有限外韧维管束和散生中柱等特点分析,表明其形态本质为茎;从零余子的芽为内起源、无顶端分生组织、主要靠初生加厚分生组织增大体积分析,则它又属于一种特殊的变态茎。

Discussion on the Development and Morphological Nature of Bulbil of Disocorea opposita Thunb.

A hulbil primordium of Dioxorea opposits originates from about 1 to 3 layers of outermost cells in the axillar. In the early stage, the cellular group of the primordium will differentiate into both of interior and exterior tissues, namely, exterior parenchyma and the saccular primary thickening meristem (PTM) adjacent to the inside as well as interior parenchyma. The PTM produces cells towards inside mostly, the derivatives differentiate into parenchyms and closed collateral vascular bundles which ' scatter in the parenchyma. The outer morphology of the bulbil of Dioxorea opposits is diversified, appearing to be massive without nodes. There are 1 to 3 adventitous buds at its base. From analysing those including in exogenous to bulbil primordium, varous transition types between the young bulbil and leaf buds as well as closed collateral bundles and atactostele, it is clear that its morphological nature may be stem; but from endogeneous to buds is bulbil, no apical structure in bulbil, and increasing in size mainly depending on the activity of PTM, thus, it is considered that bulbil is a special metamorphic stem.