Study on Bud Types and Rules of Flower Bud Differentiation and Branches' Forming in Yulania wugangensis

Some results of Yulania wugangensis are firstly studied in this paper, which are types, ramification characteristics, rules of growing into branches of buds and locus, anatomy, rules of differentiating into flowers of similar flower buds. The results as followings: (1) There are three types of buds on the spring branches of present year; latent buds, leaf buds (lateral leaf buds and apical leaf buds) and similar flower buds. (2) Similar flower bud is composed of Suotai-branchlet, stipule like bud scales, beginning branchlet, beginning leaf buds and beginning flower bud. It is called similar flower bud because it's shape likes flower bud; (3) Suotai-branchlet is transition phase between branchlet and flower setting location. It consists of the shortened, stout piece of the apex of maternal branch and first short new branchlet which developing from beginning branchlet; (4) The similar flower buds twice formed during AprilMay and JulyAugust, both experienced four stages, which are indifferentiation period, differentiation period of perianth, androecium cluster and apocarpous pistil cluster. These stages progress alternately in turn, but don't reverse and separate completely. The buds could not bloom and bear until flower buds differentiation to be over in next spring; (5) Stipule like bud scales is the anomalism of stipule, it's most outside layer is thin, coriaceous and densely covered by short fluff, which begin to fall off during the middle or last ten-days of June, and the others are paper or membranous texture and densely or sparsely covered by long fluff, which do not finish falling off till blooming in the second spring; (6) Beginning flower bud is composed of beginning peduncle, beginning flower and spathiformis stipule enveloping beginning flower; (7) Ramification characteristics and rules of growing into branches of buds belong to prolepsis and prolepsis-synlepsis, behaving the regularity of single step without branch, single step having one branch, rarely two branches. In conclusion, these results are significant to resolve the problem of numerous and jumbled about classifying and describing of Magnolia, and build a new classifying system to subfamily of Magnolioideae.