bicollateral

Collateral or bicollateral vascular bundle, developmental pith and medullary ray are obvious.

髓部达，髓射线明显。

The micrib belonging to bicollateral bundle is well developed.The bundle sheath is composed of idioblasts.

达，有异细胞组成的维管束鞘，具双生皮部。

ResultsThe root of Tylophora atrolliculata Metc. had amphicribral vascular bundle, however steme had bicollateral vascular bundle.

方法利用显微镜观察其根、茎的结构组织与根粉末特征。