5. Phyllanthus L. (leaf-flower)

(Webster, 1970)

Plants annual or perennial herbs (shrubs or trees elsewhere), monoecious or occasionally dioecious (in P. polygonoides), with clear sap, glabrous (stinging and nonstinging hairs absent). Stems erect or ascending to arched, usually branched. Leaves alternate, sessile or more commonly very short-petiolate, the petiole attached at the base of the nonpeltate blade. Leaf blades narrowly oblong or oblanceolate to oval or obovate, angled or tapered at the base, rounded or broadly angled to a usually bluntly pointed tip, the margins entire, relatively thin-textured, inconspicuously pinnately veined (often only the midvein apparent). Stipules scalelike, 1–2 mm long, usually brown, sometimes shed early, narrowly lanceolate to ovate-triangular, the base sometimes with 1 or 2 minute, rounded auricles at the base. Inflorescences axillary, of solitary flowers or small, sessile clusters of 2–4 flowers (the staminate and pistillate flowers variously positioned on different plants but in our species the staminate ones often more common toward the stem tip), usually with a small, stipulelike bract at the base, the flowers individually mostly short-stalked. Calyces deeply (5)6-lobed, 0.5–1.5 mm long (in pistillate flowers sometimes becoming enlarged to 2.5 mm as the fruits mature), oblong to obovate, rounded at the tip, persistent at fruiting. Petals absent. Nectar disc entire or more or less divided into (5)6 lobes, these broadly rounded at the tip. Staminate flowers with (2)3 free stamens (the filaments more or less arching outward). Pistillate flowers with the ovary 3-locular and 2 ovules per locule, the 3 styles separate or nearly so, each deeply 2-lobed, each lobe slightly broadened into an inconspicuous terminal stigma. Fruits 1–3 mm long, 1.5–3.5 mm in diameter, not or only slightly lobed (circular or slightly and very bluntly 3-angled in cross-section), sometimes shallowly concave at the tip, tan to yellowish brown at maturity. Seeds up to 6 per fruit, wedge-shaped, lacking a caruncle, the surface with finely warty or with minute tubercles, gray to dark brown, sometimes slightly mottled. Perhaps 750–800 species, North America to South America, Caribbean Islands, Africa, Asia, Malesia, Australia.

The generic limits of Phyllanthus are still a controversial topic (Webster, 1994). Recent molecular studies (Wurdack et al., 2004; Kathriarachchi et al., 2005; Samuel et al., 2005) have suggested that either the group needs to be split into several smaller genera or the generic concept needs to be broadened to include three or four other groups currently recognized as separate genera. Further studies are needed.