Monographs Details: Pluchea purpurascens (Sw.) DC.
Authority: Britton, Nathaniel L. Flora Borinqueña.
Description:Species Description - We include this plant in the category of maritime species, because it grows mostly in marshes or wet meadows along the coasts, within the saline influence, but it is not definitely halophytic as many others are; it ascends river valleys beyond tidal reach, and grows in the marshes bordering Laguna Tortuguera. This occurence of normally maritime plants beyond their natural habitats, and we have a number of other species similarly distributed, may, perhaps, be explained by regarding them as remnants of a distribution when the land stood lower in past geologic time; it is well known that areas now well elevated above the sea, were submerged in the Pleistocene Epoch; on the other hand this may be a plant naturally inhabiting fresh-water marshes, but tolerant of salinity. This species has a wide range in tropical and warm-temperate America, ranging north to the southeastern United States, and to Bermuda, south to Guadeloupe and southern Mexico. Another species, the shrubby Pleuchea odorata, Sour-bush, is common in Porto Rico.
Pleuchea, a genus established by Cassini in 1817, commemorates the Abbé N. A. Planche of Paris, and includes about 35 species of herbs and shrubs, natives of tropical and temperate regions. They have alternate, toothed leaves, and broad clusters of heads at the ends of the branches, composed wholly of small, tubular flowers, enclosed in a bell-shaped or hemispheric involucre with bracts overlapping in several series, and borne on a flat receptacle without chaff; the outer flowers in each head have a very slender, 5-toothed corolla, the central ones a 5-cleft corolla. The small fruits (achenes) are angled, topped by a single series of thread-like, rough bristles (pappus).
Pleuchea Purpurascens is an annual, fibrous-rooted herb, usually less than a meter high, at least the upper part finely hairy. Its broad, pointed leaves are stalked, and from 5 to 12 centimeters long, or the upper ones smaller. The flower-heads are numerous, the involucre about 4 millimeters long, the flowers pink or purplish.
Conyza purpurascens Swartz, Prodromus Descriptionum Vegetabilium 112: 1788.
Pleuchea purpurascens De Gandolle, Prodromus 2: 452. 1836.