Hamelia axillaris Sw.

  • Authority

    Elias, Thomas S. 1976. A monograph of the genus Hamelia (Rubiaceae). Mem. New York Bot. Gard. 26: 81-144.

  • Family

    Rubiaceae

  • Scientific Name

    Hamelia axillaris Sw.

  • Description

    Species Description - Shrubs to 4 m tall; bark light gray, thin, with slightly protruding conspicuous lenticels; branches terete, glabrous, sparsely lenticellate, the branchlets terete to angulate, glabrous to minutely puberulent, inconspicuously lenticellate, itswohen at the nodes. Leaves opposite, rarely ternate; petioles terete, glabrescent to densely puberulent, lacking raphides; l-4.5(-6.5) cm long; lamina narrowly ehiptic to broadly ehiptic to obovate, acuminate to long acuminate at apex, short- to long-attenuate at base, 5.2-17.5 cm long, 2.2-6.8 cm broad, glabrous above, glabrescent to sparsely puberulent below, the costa and veins puberulent, often sparse to densely barbately villous in the axils of the lateral veins, raphides conspicuous when present, chartaceous to submembranous, the lateral veins (6-)8-ll pairs, arcuate 35° to 45°, anastomosing, often conspicuously so beneath; stipules narrowly triangular, 2-6 mm long, ca. 1 mm broad at base, deciduous, sparsely vihous to glabrescent. Inflorescences ±compact compound dichasia, often appearing as short scorpioid cymes, terminal and from the upper axils, usually solitary, 14-44-flowered; peduncles terete, 5-12 mm long, glabrous to puberulent; floral axes 1.5-4.5 cm long, spreading, often slightly recurved, each axis 6-11- flowered; bracts ovate, acute at apex, ca. 0.5 long, puberulent, early caducous. Flowers secund, 1.3-1.6 cm long, usually sessile, infrequently subsessile, the pedicel to 1 mm long, floral tube campanulate to subglobose, sparsely puberulent, lacking raphides, 1.5-2.4(-3) mm long, calyx lobes oblong, 1-1.4 mm long, obtuse to subacute at apex, sparsely to densely puberulent, persistent; corolla infundibular, expanding gradually or abruptly toward the apex, chrome yellow, sparsely puberulent when young, becoming glabrate with age, lacking raphides, 1.1-1.3 cm long, the tube 3-5 mm broad, the lobesovate, acute at apex, puberulent, becoming glabrous at anthesis, erect, 1.5-2 mm long, 1.3-1.7 mm broad at base; stamens equahing the coroha tube, the filaments 4-5 mm long, the anthers 5-7 mm long, the connective forming a rounded apical appendage 0.5 mm long; gynoecium 11-13 mm long, the stigma swollen, oblong, 3-4 mm long, the style cylindrical, 8-9 mm long, the ovary 5-locular. Berries globose to globoseellipsoid, green turning red (?) then black at maturity, 5-7 mm long; seeds irregular, lustrous, finely foveolate, 0.8-1.1 mm long.

  • Discussion

    H. chrysantha Jacq., Coll. 3: 204. 1789. non Swartz, 1788. Duhamelia axillaris (Sw.) Pers., Synop. Fl. 1: 203. 1805. Hamelia appendiculata Gaertn., Fruct. Seminibus PI. 3: 64. 1805 (holotype, Desfontaines s.n., FI). H. lutea Rohr. ex Smith in Rees, Cycl. 17. 1811. H. lucida Desf., Tabl. ed. 2. 135. 1815 (grown from seed in Vienna). H. axillaris var. appendiculata (Gaertn.) D C , Prodr. 4: 442. 1830. H. breviflora A. Rich in Sagra, Hist. Cuba 11(2): 17. 1850 (holotype. Linden 2048, BM). H. declinata Sesse & Moc, Fl. Mex. ed. 2. 60. 1894. Type. Jamaica. Without exact locahty, 1784-1786, Swartz s.n. (lectotype, S). The common Hamelia axillaris is easily recognized by the short peduncles and crowded inflorescence, the small, dilated, yellow corolla tube, and the oblong calyx lobes. Although it clearly belongs to sect. Amphituba, its relationship to the other species of Hamelia is not certain. It appears to be more closely allied with H. calycosa than any other species oi Hamelia. The other seven species comprising this section have corolla tubes from 1.8-5 c m long, while the corolla tube of H. axillaris is 1.1-1.3 cm long. Readily occupying disturbed habitats, H. axillaris is often found on sand or gravel bars or on stream and river banks. Noteworthy among the synonyms is Hamelia lutea, a species that was maintained as distinct by Wernham (1911) in his revision of the genus. Standley (1930, 1931, 1931a, 1931b) in his treatments of the Rubiaceae for Colombia, Ecuador, Venezuela, and Bolivia, also considered H. lutea distinct and a common component of the lowland forest. However, when Standley (1934) treated the Central American species in North American Flora, he realized that H. lutea and H. axillaris are conspecific. Britton (1912) considered the evidence for separating the two species inconclusive and maintained H axillaris, the older name. Wernham separated the two taxa on the basis of an expanded corolla versus a tubular one. Since he drew this conclusion, I think that the material must have lacked mature flowers. Before anthesis the corolla of H. axillaris is indeed tubular! However, the coroha dilates upon opening and becomes campanulate. O n this basis it seems likely that Wernham was probably comparing immature flowers of H. axillaris with mature flowers of the same species.

  • Distribution

    Distribution. A common shrub found principally along streams and rivers at altitudes up to 1000 m. Occurring infrequently, in southern Mexico and British Honduras, Hamelia axillaris has not been reported from Guatemala, El Salvador or Honduras, but is common in Costa Rica and Panama. Its range extends along the Pacific side of South America into Bolivia and also eastward into Venezuela. It is present on most of the larger islands of the West Indies.

    Mexico North America| Belize Central America| Guatemala Central America| El Salvador Central America| Honduras Central America| Panama Central America| Costa Rica South America| Bolivia South America| Venezuela South America| West Indies|