JOURNAL OF THE ARNOLD ARBORETUMVOL. XXXVIII OCTOBER 1957 NUMBER 4 A MONOGRAPHIC STUDY OF THE WEST INDIAN SPECIES OF PHYLLANTHUS * GRADY L. WEBSTER With five platesSect. 11. Phyllanthus Phyllanthus sect. Euphyllanthus sensu Muell. Arg. in DC. Prodr. 15(2): 374. 1866 (ex p.). Annual or perennial herbs or subshrubs, with phyllanthoid branching;branchlets simple. Monoecious or dioecious, the flowers in unisexualcymules (the female then solitary) or (in a few species) in bisexualcymules. Male flower: calyx-lobes (4) 5 or 6; disk divided into segmentsisomerous with the calyx-lobes; stamens 2 or 3 (very rarely 4); filamentsfree or united into a column, anthers extrorse (except in P. maestrensis)and usually dehiscing horizontally or obliquely: pollen grains 3-or 4-col-porate, the exine reticulate. Female flower: calyx-lobes 5 or 6, usuallylarger than the male, persisting in fruit; disk entire or variously lobed ordissected; ovary smooth, obscurely stipitate; styles usually free except atthe very base, bifid, the tips of the branches thickened or more oftenslender. Capsule oblate, elastically dehiscent; columella persistent: seedssharply trigonous, variously ornamented. TYPE SPECIES: Phyllanthus niruri L. In its present limited circumscription, sect. Phyllanthus comprises about50 species, including most of the widespread weedy species in the genus.As pointed out previously (Contr. Gray Herb. 176: 51. 1955) the broadconcept of the section held by Mueller and by Pax and Hoffmann (Naturl.Pflanzenf. 2 ed. 19c: 64. 1931) was unnatural, many unrelated plants beinggrouped together on the basis of the single criterion of three stamens withmore or less horizontally dehiscing anthers. This artificial sect. Euphyllan-thus in fact included representatives of six of the eight subgenera nowrecognized in the West Indies! As presently constituted, however, there * Continued from volume XXXVIII, p. 198.