WEBSTER. WEST INDIAN PHYLLANTHUS A MONOGRAPHIC ST I)Y OF THE WEST INDIAN SPECIES OF PHYLLANTHIS $S GRADY L. WEBSTER With five platesSect. 18. Orbicularia (Baill.) Griseb. Fl. Br. W. Ind. 34. 1859. Orbicularia Baill. Etud. Gen. Euphorb. 616. 1858. Roigia Britton. Mem. Torr. Bot. Club 16: 73. 1920. Dimorphocladium Britton. ibid. 74. Phyllanthus sect. Dimorphocladium (Britton) Pax & Hoffm. Natiirl. Pflanzen-fam. 19c: 63. 1931. Shrubs with phyllanthoid branching, axes smooth and glabrous; leaveswith mesophyllar sclereids, mostly coriaceous, stipules (at least proximalones) mostly persistent. Monoecious; cymules male and bisexual, femaleflowers usually only one per cymule. Male flower: calyx-lobes 6 (rarely5); disk-segments free or coalescent; stamens 3-7, filaments united en-tirely or below into a column; pollen grains areolate. Female flower:calyx-lobes 6 (rarely 5); disk tenuous to rather massive; ovary sessileor slightly stipitate; styles free or connate below into a column, the freeends bifid, style-branches often revolute at the tips. Capsule oblate, veinsconspicuous or obscure; seeds trigonous, verruculose. TYPE SPECIES: Orbicularia phyllanthoides Baill. I-lPhyllanthus orbi-cularis HBK.] Although a well-marked and apparently monophyletic group, which hereis given essentially the same circumscription as that of Carabia (Ecol. Mon.15: 335. 1945), sect. Orbicularia is rather difficult to characterize as dis-tinct from neighboring sections in subg. Xylophylla. The most closelyrelated section, from which sect. Orhicularia has probably been derived.is sect. Williamia. The species of the latter with sclerified leaves (subsect.Incrustati) can be distinguished from the present group only by theirincrustate axes and lacerate style-tips. After a prolonged study which has been pursued intermittently overa period of several years, the following treatment of sect. Orbicularia ispresented with some diffidence. Despite personal field observations inCuba in 1951 and 1953 and the analysis of a considerable number ofherbarium specimens, a definitive resolution of the taxonomic problems inthe group has not been achieved. Field studies have been of value in dem-onstrating (to the author's satisfaction, at least) that some of the confu-sion in the literature is traceable to the striking differences in leaf formbrought about by different ontogenetic changes and/or responses to dif-ferent ecological situations. Thus it appears that the very glossy and * Continued from volume XXXIX, p. 100.1958j
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