Flora of North America species comparison

Phyllanthus tenellus is easily recognized by its long, capillary pistillate pedicels that are flexuous and pendent in fruit; it is native to the Mascarene Islands and perhaps to eastern Africa, other western Indian Ocean Islands, and the Arabian Peninsula, and is widely naturalized in tropical and subtropical regions worldwide. It appears to have been introduced into Florida in the 1920s and is continuing to spread. Phyllanthus tenellus has been reported from Arkansas (E. Sundell et al. 1999) and California as a nursery weed (G. F. Hrusa, pers. comm.), and from Oklahoma in flower beds (B. W. Hoagland, pers. comm.), and may be expected to become naturalized in those states.

(Discussion copyrighted by Flora of North America; reprinted with permission.)

Species 800–850 (16 in the flora).

Phyllanthus is by far the largest genus in Phyllanthaceae and shows tremendous diversity in habit, from trees to small annual herbs, including a floating aquatic herb. Most species exhibit phyllanthoid branching (G. L. Webster 1956–1958), with well-developed leaves and flowers produced only on the ultimate branchlets, which in woody species are deciduous, and scalelike leaves on all other stems (referred to as main stems in this treatment; see family discussion for more details). Phylogenetic studies using DNA sequence data suggest that phyllanthoid branching evolved once and has been lost repeatedly, including within the clades containing P. caroliniensis and P. warnockii (H. Kathriarachchi et al. 2006). These studies also indicated that Phyllanthus is paraphyletic and that few of the subgenera and sections used by Webster (1956–1958, 1967) are monophyletic (K. Wurdack et al. 2004; Kathriarachchi et al. 2005, 2006; P. Hoffmann et al. 2006). However, it is premature to revise the classification of the genus (Kathriarachchi et al. 2006) and the sequence of species used here generally follows the classification by Webster (1956–1958, 1967, 1970). Exceptions are P. warnockii, which he treated as the sole member of Reverchonia but molecular phylogenetic studies show to be embedded in Phyllanthus (Kathriarachchi et al. 2006), and P. fluitans, which he did not treat; the latter species appears to be closely related to P. caroliniensis (Kathriarachchi et al. 2006).

A number of Phyllanthus species are of economic importance. Some cladode-producing species, especially P. angustifolius and P. epiphyllanthus Linnaeus, are grown as ornamental shrubs in tropical and subtropical areas (and in hothouses elsewhere); the former species has become sparingly naturalized in south Florida. Otaheite (or Tahitian) gooseberry tree, P. acidus, is grown throughout the tropics for its tart drupes; it has naturalized in south Florida. The floating aquatic herb P. fluitans (floating spurge or red root floater), is increasingly popular for use in tropical fish aquaria. Both P. amarus and P. urinaria have become weeds throughout tropical and subtropical areas, including the southeastern United States, and the American P. caroliniensis has become a weed in southeast Asia. Several annual species, notably P. niruri and P. urinaria, are widely used in folk medicine to treat a variety of ailments, especially urinary problems, and are now the subject of intense pharmacological research.

In Phyllanthus, taxa that are not consistently distinct morphologically but are geographically disjunct are recognized as subspecies (for example, P. caroliniensis subspp. caroliniensis and saxicola). Those that intergrade morphologically and geographically, as in P. abnormis, are treated as varieties.

(Discussion copyrighted by Flora of North America; reprinted with permission.)