Anatomical and morphological studies in the Chenopodiaceae. I. Inflorescence of Atriplex and Bassia

Abstract

Antomical techniques were employed to explain the morphology of the inflorescence of certain Australian species of Atriplez L. and Bassia All. Clearing of tissues by chlorallactophenol was used extensively and proved to be superior to the slow conventional method of sectioning and reconstruction. Vascularization of the stem and the inflorescence was studied and described. It was found that the inflorescences of Atriplex are of two types. One is terminal in origin; and the second is axillary, containing female flowers, and is complex, being a much condensed form of compound dichasium. The lateral branches of such an inflorescence are always dichasia of female flowers, but the terminal branch is variable and can be either a male dichasium, a female flower, or a vegetative shoot. The solitary flower of Bassia is derived from the suppression of the lateral branches of such an inflorescence and a reduction in the number of flowers in the terminal branch. Two species of Bassia, however, bear an inflorescence which is a condensed dichasium. Attention is drawn to the similarity of the vascular system of the male inflorescence of Atriplex and the primary vascular system of the Bassia stem. The development, morphology, and anatomy of the fruiting bracteole of Atriplex is described in some detail and it is concluded that it is a true bracteole.