The Genus Hoffmannia (Rubiaceae) in Panama

Abstract

Eleven new species of Hoffmannia (Rubiaceae) and diagnoses of nine previously described species from Panama are presented. A key to the species is included. The tropical genera Hoffmannia Sw., Hamelia Jacq., and Bertiera Aubl. constitute the tribe Hamelieae of the Rubiaceae, with the first two genera restricted to the tropics of the New World. Paul Standley, in his treatment of Hoffmannia in the North American Flora (Rubiales-Rubiaceae (pars) 32(3): 190-208, 1934), recognized 50 species extending from Mexico to Panama, with two species, H. pedunculata Sw. and H. tubiflora Griseb. & Desv., occurring in the West Indies. Airy Shaw (in Willis, A Dictionary of the Flowering Plants and Ferns ed. 7, Cambridge Univ. Press, 1966) notes that there are 100 species of Hoffmannia. Standley, in the North American Flora (loc. cit., pp. 191-193), as well as in the Flora of Costa Rica (Publ. Field Mus. Nat. Hist., Bot. Ser. 18: 1311-1313, 1938) furnishes the only keys to species of Hoffmannia published in relatively recent times; these are accompanied by specific diagnoses. Hoff mannia is a genus of the rain forest with the majority of species occurring at higher altitudes. In Panama, for example, Hoffmannia is generally found at altitudes of 3000 to 6000 ft, although a few species may occur at sea level or at low elevations. Panama seems to represent a good collecting ground for Hoffmannia and is rivaled or surpassed in number of species only by Costa Rica and Guatemala. The fact that eleven new species from Panama are described in this paper suggests the need for an intensification in the collecting of the genus, at least in Central America. Prior to 1959 only about 50 collections from Mexico and Central America were to be found in the herbarium of the Missouri Botanical Garden, with the majority of these from the Province of Chiriqui in Panama. Not a solitary collection from the Panamanian Province of Darien was numbered among these. In the last decade about 50 new Panamanian collections have been added to the herbarium. Particularly noteworthy are the 1968 collections of Dr. James Duke and Mr. Joseph Kirkbride, Jr. from the provinces of Bocas del Toro, Chiriqui, and Darien. Currently, Hoff mannia is known from seven of the nine provinces of the Republic; thus far the genus has not been collected in the provinces of Herrera and Veraguas. The genus Hamelia seems to be the lowland counterpart of Hoffmannia. In Panama Hamelia is rarely seen at high elevations, although the author has seen H. patens Jacq. in the region of Boquete, Prov. Chiriqui, at approximately 5000 ft elevation. Several-characters give evidence of the natural relationship of the two genera: imbricate petals, numerous ovules borne on axile placentas, reticulate ANN. MISSOURI BOT. GARD. 56(2): 269-286, 1969. This content downloaded from 207.46.13.120 on Thu, 15 Sep 2016 05:33:28 UTC All use subject to http://about.jstor.org/terms