Ageratina glabrata

Ageratina glabrata displays these main distinguishing features:

It is a woody shrub up to 2.4 meters tall (~8 feet). Its leaves, arising in pairs opposite one another, are longer than wide, with a pointed tip, and margins which are toothed to almost smooth. Blades are hairless and somewhat resiny-shiny, with the lower surface dotted with glands; leaf texture ranges from thin to somewhat leathery. Flowers are arranged in heads consisting only of 15-18 disk florets with cylindrical corollas; the heads are arranged in cyme-type inflorescences. Corollas are white, sometimes with pinkish lobes, and up to about 7 mm long (+3⁄16 inch). The fruit is a one-seeded, non-splitting, "cypsela" with a pappus almost as long as the corolla.

Ageratina glabrata is endemic to Mexico, from the northern states of Sinaloa, Durango and Tamaulipas south to Oaxaca and Puebla.

Ageratina glabrata has a continuous flowering pattern throughout the year. Relative to closely related species, its greater height and cover suggest an adaptation to open environments.

In Mexico, Ageratina glabrata is considered to have analgesic activity; one of its names is hierba del golpe, which can be translated loosely as 'plant for hits'. Preliminary results of controlled tests with rats using the "hot plate"and "tail flick tests" suggested that treatment with extracts of the plant provided analgesic effects for 5 hours after its administration. Another study, noting the shrub's traditional use for stomach pain and for postpartum baths, found that Ageratina glabrata contains antioxidants that might explain the usefulness.

The genus name Ageratina is based on another genus, Ageratum, plus the Latin diminutive suffix ina. Species in the two genera are very similar and dozens of species have been reassigned from Ageratum into Ageratina. The species epithet glabrata is based on the Latin glaber meaning 'smooth, bald', likely referring to the species' hairless leaves. In 1818, Kunth formally described the leaves of the type specimen as "... subcarosa, glabra...", suggesting the name glabratum.