Introduction to the study of the Rubiaceae Family in the Province of Santa Fe (Argentina) I: Tribe Spermacoceae

RAMÍREZ, EVELYN; VÁZQUEZ, IRIS; CHAMORRO, D.; PALOU, D.; PRADO, D.E.; OAKLEY, L.J.

Rosario

Congreso; XLI Reunión de Biología de Rosario; 2021

Sociedad de Biología de Rosario

The Family Rubiaceae was historically placed in the order Rubiales, but according to APG IV it is currently considered part of Gentianales. It includes trees, shrubs or herbs, generally unarmed with opposite, simple and entire leaves with stipules. Flowers solitary or grouped in cymose inflorescences, actinomorphic, pentamerous or tetramerous, petals with indument in adaxial face; stamens 4-5 with filaments adnate to corolla; carpels usually 2, ovary inferior with 1 to numerous ovules. Dry or fleshy fruits. According to the classical classification system, the family comprises three subfamilies: Rubioideae, Cinchonoideae and Guettardoideae. The first one presents some tribes, among them Spermacoceae, made up of herbaceous or shrubby plants, with stipules in the form of a fimbriated sheath, flowers tetramerous, ovary with two uniovulate locules and fruit a schizocarp, capsule or pixidium. The objective of this work is to initiate the taxonomic study and analyze the geographical distribution of the Rubiaceae Family in Santa Fe, beginning with the Tribe Spermacoceae. The methodology consisted of bibliographic review, consultation of herbaria with important collections of the province (SF, SI, UNR), observation of most of the species in their habitat and lab work to corroborate determinations. The preliminary results show that the Tribe Spermacoceae is represented by five genera and 12 species, all herbs or suffrutices. These are: Borreria G. Mey., with B. dasycephala (Cham. & Schltdl.) Bacigalupo & E.L. Cabral; Mitracarpus Zucc., with M. megapotamicus (Spreng.) Kuntze; Galianthe Griseb., with G. centranthoides (Cham. & Schltdl.) E.L. Cabral, G. eupatorioides (Cham. & Schltdl.) E.L. Cabral and G. palustris (Cham. & Schltdl.) E.L. Cabral; Richardia L. with R. brasiliensis Gomes, a perennial herb and crop weed, R. humistrata (Cham. & Schltdl.) Steud. and R. stellaris (Cham. & Schltdl.) Steud.; and Spermacoce L. with S. eryngioides (Cham. & Schltdl.) Kuntze, S. glabra Michx., S. hassleri E.L. Cabral & J. Florentin, both typical of humid environments and S. verticillata L., rhizomatous suffrutex with markedly tetragonous stems. Taxonomic information, illustrations, a map of geographical distribution of the species and a dichotomous key based on morphological features are presented.