摘要
甘遂根在发生次生生长后，局部区域的木栓形成层向内产生多层栓内层细胞，这些细胞不断扩大，使这一区域的根发生膨大。以后维管形成层开始活跃，产生薄壁组织化的次生维管组织，同时栓内层继续增加．从而形成了块根。由次生木质部中胶质纤维形成的薄壁组织细胞也参与了块根的后期膨大。块根的这种形成方式应为一种异常生长。块根发育过程中，各种薄壁组织细胞中淀粉粒的数目及体积不断增加．甘遂根中的乳汁管为无节、分枝和多核的，不具淀粉粒。
The development of the root tuber of Euphorbia kansui Liou was studied based on the obser-vations of development of primary and secondary structure of the root。The formation of primary and secondary structure of the root showed the similarities to thatof other herbaceous dicotyledons。 But in the secondary structure,the phellogen,which was formedby the periclinal division of pericycle cells,produced more layers of cells inside than outside。Therefore,the cell layers of phelloderm were more than that of cork in the periderm,The vascularcambium also Droduced more cells inside than outside.The cells in the secondary xylem differenti-ated into more gelatious fibers and less vessels。 After that,the phellogen produced more phello-derm cells and this caused the primary root tuber;The phelloderm cells continuously increased un-til the root tuber stoped expanding。 That was the main cause of the root tuber expanding。 Whenthe root tuber reached to 1一2mm in diameter,the vascular cambium became active, It produced more cells inside than outside also. In the secondary xylem,these cells did not differentiate intogelatinous fibers any more , but into more xylem parenchyma cells and less vessels. In the sec-ondary phloem, most cells differentiated into phloem parenchyma cells。 The increase of the sec-ondary parenchyma cells was another reason of the root tuber expanding; When the root tuberreached to 3一5 mm in diameter, the gelatinous fibers grew intrusively inter the vessels ofmetaxylem, then changed into parenchyma cells and sorted out the parimary xylcm ridges fromeach other, These cells formed a parenchyma region in the center of the root tuber later。 Whenthe root tuber reached to 10一15 mm in diameter,the cells from the vascular cambium in the raysdifferentiated into new phloem strands outside firstly,and then into new xylem strands inside, Atthis time,the root tuber would stop expanding。1 the developmental process of root tuber,the starch grains in the parenchyma cells in-creased. The laticifers in th
出处
《西北植物学报》
CAS
CSCD
北大核心
1995年第2期104-109,共6页
Acta Botanica Boreali-Occidentalia Sinica
基金
国家自然科学基金资助项目
关键词
甘遂
块根
发育
解剖
大戟科
Euphorbia kansui,root tuber, development,starch grain,laticifer
