446 MORPHOLOGY OF THE ANGIOSPERMS 



that subtended lost branchlets. The bracts are connate and form a 

 protective shell for a pistillate flower. The acorn cup of Quercus is, 

 morphologically, a closely similar structure. 



The scales of die lorica show a phyllotactic arrangement similar to 

 that of the leaves. Though the scales have been described as lacking 

 vascular bundles, bundles are shown in some illustrations. The presence 

 of these bundles is evidence that the scales are not emergences. (It is 

 probable that, commonly, the vascular tissue in these organs may not 

 have matured at the flowering stage, the stage usually studied.) 



It has been argued that the scales of the lorica are lobes of the ovary 

 wall and, therefore, cannot represent bracts. There has been little his- 

 tological study of the structure of the lorica wall, but stages in the 

 adnation of the scales to the carpellary wall have been described. The 

 carpels may be completely free from the lorica; they may be adnate 

 but histologically distinct (Laccospermo); in other genera, the fusion of 

 scales and ovary wall seems complete. (Further anatomical study of 

 palm flowers of this type should be made.) Loricate flowers represent, 

 without doubt, one of the many forms of inflorescence reduction in the 

 palms. 



Various genera show stages in the evolutionary development of the 

 lorica. In Zalacca, partial inflorescences are clustered in a head or club- 

 shaped mass. In Latania, the flowers are borne on very slender branch- 

 lets, each flower subtended by an adnate bract. In Eugeissona tristis, 

 the lorica is weakly developed; the scale units are bractlike in form. 



The Flower 



In general structure, the flower of the palms is of the monocotyle- 

 donous type, with trimerous whorls and various degrees of connation 

 and adnation. It ranges from bisexual to unisexual, and the unisexual 

 from monoecism to dioecism. Only a few genera have bisexual flowers — 

 most of the Sabal palms and some of the Lepidocaryoideae. The sub- 

 family Ceroxyloideae shows all transitional stages from bisexual to uni- 

 sexual flowers, and, in the location of unisexual flowers, from both 

 sexes in the same inflorescence to separation of the sexes in different 

 inflorescences in the same plant and on different plants. Dioecism is 

 uncommon or rare — Raphia, Phoenix, Phijtelephas. Monoecious taxa are 

 of two types: those with staminate and pistillate flowers in the same 

 inflorescence, even side by side; and those with the two floral types in 

 different parts of the same inflorescence. Nearly all unisexual flowers 

 have vestigial sporophylls of the reduced sex and show all stages of 

 reduction to complete disappearance of these abortive organs. Only in 

 strongly dioecious taxa are there no vestiges of abortive sporophylls. 



