何首乌幼苗的解剖学及过渡区的初生维管系统

Anatomical Character and Primary Vascular System of Polygonum multiflorum Seedling

采用石蜡制片方法,对何首乌幼苗进行了解剖学研究。结果表明:何首乌幼苗类型为木兰型。根为四原型,通常无髓部。子叶和初生叶的上表皮无气孔器分布,表皮细胞垂周壁平直;下表皮的表皮细胞垂周壁波浪状,有较多的气孔器,气孔器属无规则型。子叶柄中有3个维管束,初生叶的叶柄中有6个维管束。何首乌幼苗的过渡区位于下胚轴,根的4个放射维管束,在下胚轴中通过初生韧皮部的拉长、断裂、合拢,形成4个并生维管束,以后相对的2个维管束均一分为二,成为6个维管束。下胚轴在分裂的维管束处裂成两部分,每部分各具3个维管束,与两片子叶的各3个子叶迹相连。根-下胚轴-子叶的维管束成为一个初生维管系统。

The anatomical characteristics as well as primary vascular system of Polygonum multiflorum seedling were investigated in the current work.The results showed that the seedling type of Polygonum multiflorum is Magnolia Type.Primary xylem in main root is tetrarch.The adaxial epidermis of cotyledon and primary leaf without stomatal apparatus,the anticlinal wall of epidermis cell is straight.The anticlinal wall of epidermis cell is wavy,and with many anomocytic type stomatal apparatus distributing in abaxial epidermis of cotyledon and primary leaf.There exist three vascular bundles in the petiole of cotyledon,and six in primary leaf.The transition region of Polygonum multiflorum seedling lies in its hypocotyl.Four radiate bundles of the root come into being four collateral bundles via elongating,rupturing and folding of primary phloem in the hypocotyl.Every two opposite vascular bundles among four collateral bundles will divide into two parts,thus there are six vascular bundles in the hypocotyl.The hypocotyl separates into two parts from partite vascular bundles,there are three vascular bundles in each part,and the three vascular bundles join with three traces of each cotyledon.The vascular bundles of root,hypocotyl and cotyledon turn into primary vascular system,whereas the vascular bundle from the stem comes into being alone.