Ageratum conyzoides: A Tropical Source of Medicinal and Agricultural Products

BOTANY Ageratum is derived from the Greek “a geras,” meaning non-aging, referring to the longevity of the flowers or the whole plant. The specific epithet “conyzoides” is derived from “kónyz,” the Greek name of Inula helenium, which it resembles (Kissmann and Groth 1993). The synonyms of A. conyzoides include A. album Stend; A. caeruleum Hort. ex. Poir.; A. coeruleum Desf.; A. cordifolium Roxb.; A. hirsutum Lam.; A. humile Salisb.; A. latifolium Car.; A. maritimum H.B.K.; A. mexicanum Sims.; A. obtusifolium Lam.; A. odoratum Vilm. and Cacalia mentrasto Vell. (Jaccoud 1961). In Brazil, A. conyzoides has the following vernacular names: catinga de bode, catinga de barrão, erva de são joão, maria preta, mentrasto, erva de são josé, picão roxo, erva de santa-lúcia, camará-opela, agerato, camará apeba, camará iapó, camará japê, erva de santa maria, macela de são joão, macela francesa, matruço (Jaccoud 1961; Oliveira et al. 1993). Ageratum ranges from Southeastern North America to Central America, but the center of origin is in Central America and the Caribbean. Most taxa are found in Mexico, Central America, the Caribbean, and Florida. Ageratum conyzoides now is found in several countries in tropical and sub-tropical regions, including Brazil ( Baker 1965; Lorenzi 1982; Correa 1984; Cruz 1985). Johnson (1971), classifies two subspecies, latifolium and conyzoides. Subspecies latifolium is found in all the Americas and subsp. conyzoides has a pantropical distribution. The basic chromosome number is 2n = 20 but natural tetraploids are found. A. conyzoides subsp. latifolium is diploid and A. conyzoides subsp. conyzoides is tetraploid. Ageratum conyzoides is an erect, herbaceous annual, 30 to 80 cm tall; stems are covered with fine white hairs, leaves are opposite, pubescent with long petioles and include glandular trichomes. The inflorescence contain 30 to 50 pink flowers arranged as a corymb and are self-incompatible (Jhansi and Ramanujam 1987; Kaul and Neelangini 1989; Ramanujam and Kalpana 1992; Kleinschimidt 1993). The fruit is an achene with an aristate pappus and is easily dispersed by wind. In some countries the species is considered a weed, and control is often difficult (Lorenzi 1982; Scheffer 1990; Kalia and Singh 1993; Lam et al. 1993, Paradkar et al. 1993; Waterhouse 1993; Kshatriya et al. 1994). Seeds are positively photoblastic, and viability is often lost within 12 months (Marlks and Nwachuku 1986; Ladeira et al. 1987). The optimum germination temperature ranges from 20 to 25°C (Sauerborn and Koch 1988). The species has great morphological variation, and appears highly adaptable to different ecological conditions.