Histogenesis of the inflorescence and flower of Triticum aestivum L.

Abstract

In Triticum the apical meristem of the spike and spikelets is similar to that of the vegetative axis: a two-layered tunica encloses a central corpus. Leaf primordia arise by the periclinal division of cells of the tunica, the corpus contributing nothing to their development. Spikelet primordia are initiated in periclinal divisions of cells of the outer layer of the corpus (sub-hypodermis). Their mode of origin is comparable with that of vegetative buds. The glumes and lemmas arise in the same manner as the foliage leaf; the flower primordia by divisions in the sub-hypodermis like the spikelets. The early histogenesis of the palea, lodicules, and carpel is also essentially the same as that of the foliage leaf, whilst the stamens arise as cauline structures like the spikelets and flower primordia. The ovule is derived directly from the apex of the flower primordium and the integuments originate in the manner of foliar structures. The significance of these observations in the interpretation of the floral morphology of Triticum is discussed.