The Anomalous Structures of Achyranthes bidentata Blume(Amaranthaceae)

The developmental and the anatomical structures of anomalous structure in the axes of Achyranthes bidentata were examined with anatomical methods.The results showed that the primary and initial secondary growth of the root resembled those of usual dicots.Afterwards,4-5 rings supernumerary cambiums occurred centrifugally.Each cambium produced tertiary vascular bundles and conjunctive tissues in a bidirectional manner.However,there were two types of anomalous structures in the stem of A.bidentata.In the development of stem,when the differentiation of secondary vascular bundle was finished,a ring supernumerary cambium originated from the one or two layers cells of procabium which remained the outside of secondary vascular bundle.And the activities of the supernumerary cambium produced the tertiary vascular bundle.In addition,there was no correlation between the two medullary bundles that also originated from procambium and normal vascular bundles in the position.But there were multiformity on the types of the structure of medullary bundle.And sometimes incomplete amphivasal bundles were formed.