Flora of North America species comparison

Portulaca pilosa is a highly variable species. It exhibits morphologic variability during development, with immature plants having wider (to 4 mm), longer, and flatter leaves than mature specimens. Mature leaves are narrower, shorter, and hemispheric or terete in cross section. The Linnaean drawing of the type specimen may be an immature plant. Morphologic variability also occurs in relation to habitat differences over the large geographic range of this species. Plants growing in dry habitats have the greatest density of hairs; plants growing in moist habitats are less pilose. Plants with very dense hairs on old growth will, under more moist conditions, produce new growth with fewer hairs. Growth habit is also affected by habitat. Plants growing in warm, moist environments tend to branch quickly into a spreading habit, with erect growth following secondarily. Plants in cool, dry habitats grow erect first, then branch more slowly; the plant then has a compact habit. Specimens from Alabama, Arizona, Florida, Louisiana, Mississippi, New Mexico, and Texas exhibit all morphologic conditions. Those from Arkansas, Kansas, Missouri, and Oklahoma usually occur in shallow, sandy soils, often on rocky outcrops, and are often highly branched, compact, short, and not very pilose.

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

A. P. Simopoulos and N. Salem Jr. (1986) and A. P. Simopoulos et al. (1992) have shown Portulaca oleracea to have the highest content of omega-3 fatty acids and antioxidants of any green leafy vegetable examined to date, suggesting that common purslane should be considered for its nutritional value and not for its weediness. It has long been used as fodder and may have been present in the New World in pre-Columbian times (R. Byrne and J. H. McAndrews 1975). Currently, it is fed to poultry to reduce egg cholesterol.

Portulaca oleracea is a highly variable species with worldwide distribution in temperate to warm regions and is the most winter-hardy of all the portulacas. It is a very aggressive weed, one of the ten most noxious weeds worldwide (J. S. Singh and K. P. Singh 1967). As such, many variants have been named (C. D. Legrand 1962) based on seed surface differences, size of seeds, or on variable characters of growth habit, leaf length, and number of stamens. Seven subspecies were recognized by A. Danin et al. (1978): subsp. oleracea, subsp. impolita Danin & H. G. Baker, subsp. granulatostellulata Danin & H. G. Baker, subsp. nicaraguensis Danin & H. G. Baker, subsp. nitida Danin & H. G. Baker, subsp. papillatostellulata Danin & H. G. Baker, and subsp. stellata Danin & H. G. Baker.

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