北乌头附子的发育解剖学

THE DEVELOPMENTAL ANATOMY OF THE MONKSHOODTUBER OF ACONITUM KUSNEZOFFII

北乌头(Aconitum kusnezuffii)附子是一种特殊的结构,附生在植株的根旁,由一个顶芽、腋芽以及块根状的不定根组成。附子上的腋芽出现后的第二年3月,在腋芽第一节下方,远轴一侧的部分近似形成层细胞分化,形成了直接与芽端原形成层连接的不定根原基。同时,腋芽第一节间横向伸出成为连接母株的“桥”。随着不定根上部韧皮部薄壁组织细胞的增生,此根不断增粗,变成了新的附子,6月达到最大。这种附子的顶芽则是在7月后才迅速发育,直到10月后休眠,第三年春再发展成为新的植株。因此,附子实际上是一个具有膨大不定根的更新芽。而连接母株的“桥”则是腋芽第一节间所形成的一种特殊的地下茎。

The monkshood-tuber of Aconitum kusnezoffii is a specialized structure attached to the root of the plant and is composed of apical bud,axillary bud and its tuberous adventitious root. After the axillary bud emerges at the end of March of the following year,the primordium of the adventitious root develops from the procambium-like cells of the bud just below the first node at the abaxial part.With the active proliferation of the secondary phloem parenchyma cells,the root increases its size very rapidly to form a“tuber”,When the adventitious root begins to develop,the first internode of the axillary bud extends horizontally to form a“bridge” connecting the daughter monkshood-tuber to the mother plant.In the third spring,each“tuber” sprouts one shoot giving rise to a new plant and in likewise produces a new“tuber”. It might be concluded that the monkshood-tuber is a renewal bud developing from a axil— ary bud The so called“bridge”which connect the“tuber”and the mother plant is a spe- ciaI kind of subterraneous stem which is actually the first internode of the axillary bud.