A study of the developmental morphology and anatomy of the floral parts of Triticum aestivum L

摘要

The arrangement of outer three layers (i.e. dermatogen, hypodermis, and subhypodermis) in the spikelet apex and floret primordium is similar to that of the vegetative apex. In their origins the lemma, palea, lodicules, carpel and integuments are leaf-like, whereas the floret and stamen primordia are similar to axillary buds. The integuments arise almost entirely from the repeated divisions of dermatogen cells, Each stigmatic hair develops by the elongation and characteristic division of a single epidermal cell of the stigma. A main vascular strand enters the base of each lodioule and by repeated divisions forms a ramification throughout the lodicule. The procambium appears as an isolated patch of tissue in the position of the future median and lateral strands of the carpel and of the single strand of the stamen. The first appearance of the procambium is restricted to the middle region of the future longitudinal course of the strand. From this point of origin each procambial strand continues its initiation both acropetally and basipetally. A similar pattern of origin and differentiation has been observed for the initiation and propagation of the first protophloem element. It holds also for the first element of protoxylemin the stamen. In the funicular strand the differentiation of the pro-cambium and the vascular elements is acropetal. Comparable stages in the initiation of the carpel and the differentiation of the procambium have also been observed in Avena, Oryza and Secale. The significance of the above observations is discussed. Some observations are also made on the ultra structure of differentiating protophloem elements of the stamen.