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.