5. Phyllanthus L. (leaf-flower)
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.
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.