Morphogenesis and Anatomy of Fissurate Growth of Potaninia Mongolica
劈裂生长的形态发生及内部解剖结构特征的研究

Many xerophilous plants have such a vegetative reproduction,fissurate growth.Some super xerophilous plants such as Potaninia mongolica,Reaumuria soongorica,Reaumuria trigyna,Salsola passerina,Caragana stenophylla,etc.in Erdos region of Inner Mongolia have this characteristic.Potaninia mongolica is a typical fissurate growth species here.It is the archaic single species genus plant and belongs to Rosaceae.It can adapt to drought environment well.Potaninia mongolica has breeding system with sexual and vegetative reproduction,and the latter is the main type,which has two modes: one is that the branches drop and grow new vegetal body,the other is fissurate growth.Many xerophilous plants in Erdos region of Inner Mongolia share the same characteristic,fissurate growth,which is a special adaptive strategy for them to adapt to the droughty environment.But the correlated study on fissurate growth is few,and it is the first report that the study on morphogenesis and anatomy of fissurate growth of Potaninia mongolica.In this study,we selected typical fissurate growth species,Potaninia mongolica that living in west Erdos region of Inner Mongolia,to study the morphogenesis and anatomy of fissurate growth.We gathered the root and stem of unfissurate body and fissurated body,dealt with them with FAA,and observed and made a picture after making sections.The results are as follows:(1) Fissurate growth of Potaninia mongolica had two types: one is root firstly split,and then above-ground stem split later,and every fissurate part formed single body,but the other was opposite.(2) Fissurate growth started from the base of stem.During certain phases of growth,the cambium layer of this part was asymmetric,the arrangement of xylem was anomalistic,and formed the wreathlike structure.And then the adjoining constrictions started to split.(3) As the influence of fissurate growth,the annual ring of the root of fissurated body was irregular.The cambium layer of the fissurate part was asymmetric,the vessel of secondary xylem became less and smaller,while the amount of xylem fiber increased.The cells became tighter and the constriction formed.