英文摘要 |
The external morphology as well M the differentiation and maturation of the vascular tissue of the root and initiation of lateral root in Ceratopteris thalictrcides (L.) Brongn. are studied. At maturity leaf length is negatively correlated with leaf age. The initial cells of all tissues of the root are present a few cells behind the apical cell. The sequence of the differentiation and maturation of each tissue is strictly constant. Metaxylem appears first but matures last among all of the other vascular tissues. Protophloem is identified next to the metaxlem and matures before the protoxylem appears, then protoxylem matures before the metaxylem matures. The lateral root initial arises in the endodermis at about five cells behind the apical cell. The endodermis matures by the formation of a Casparian strip before the metaxylem matures and after protoxylem Maturation. The air spaces arise schizogenously very close to the apical cell usually before the earliest metaxylem appears. The lateral root is derived endogenously from a s ingle enlarged endodermal cell at a definite place. But no other morphologically difference can be seen in this special lateral root initial. |