Rhynchosia edulis Griseb.

Authority

Grear, John W. 1978. A revision of the New World species of Rhynchosia (Leguminosae-Faboideae). Mem. New York Bot. Gard. 31 (1): 1-168.

Family

Fabaceae

Scientific Name

Rhynchosia edulis Griseb.

Description

Species Description - Herbaceous vine usually, 0.4-4.5 m, the stems one to few from woody base, erect to suberect, decumbent, procumbent or twining, simple or branching, angular to subterete (on older stems), barely to highly viscid, yellowish hirsute, the hairs spreading or appressed, older stems becoming glabrate. Stipules linear to narrowly lanceolate, acute to acuminate, hirsute, persistent, 3-9 mm long, 0.5-1.5 mm wide. Petioles hirsute, viscid to some degree, 1.5-5.5 cm. Leaflets 3, membranaceous to thin-coriaceous, lanceolate to ovate-oblong or ovate-deltoid to rhomboid, acute to acuminate, base obtuse to rotund or truncate, margins shortly ciliate and slightly revolute, 1.5-6(-7.5) cm long, l-5(-6) cm wide, strigulose to sparsely strigose (finely or loosely) above, often minutely muricate, sparsely to densely hirsute beneath, especially along major veins, and gland-dotted yellow or black, often viscid on both surfaces, terminal petiolule 5-20(-25) mm, the laterals subobsolete to 2 mm, stipels setiform, 0.5-2.5 mm. Inflorescences equal to or exceeding the leaves, 2.5-19(-20) cm, branching, flowers lax, peduncle 1.5-7 cm, pedicels 1-3 mm. Bracts ovate, acuminate, caducous, 2-3 mm long, 0.5-1 mm wide. Calyx not exceeding the corolla, hirsute, viscid to some degree, 4-7 mm, tube 1.5-2 mm, lobes lanceolate, long-attenuate, 2-5 mm, vexillar sinus 1.5-3 mm. Corolla yellow, often striped reddish-brown or purple, 7-10 mm. Standard widely ovate to obovate, slightly apiculate, hirsutulous and gland-dotted, 7-10 mm long, 4-6 mm wide, auricles 0.5 mm, claw 1-1.5 mm. Wings narrowly oblong, slightly gland-dotted and puberulous at apex, 6.5-9 mm long, 1.5-2 mm wide, claw 1.5-2 mm. Keel blades falcate, glabrous, 6.5-9 mm long, 2-3 mm wide, claw 1.5-2 mm. Stamens 6-9 mm. Fruits oblong-ovate, compressed, gland-dotted, often viscid, long hirsute and puberulous intermixed and becoming glabrate with age, 16-26 mm long, 6-8 mm wide, beak oblique, 3-5 mm. Seeds widely ovate or subglobose, compressed, greenish-brown, black or mottled, 4-5 mm long, 3-4 mm wide, hilum linear-ovate, 1-2 mm, strophiole lobes linear.

Discussion

Rhynchosia melanosticta Grisebach, Abh. Bohm. Ges. Wiss. Goet. 19: 123. 1874, in synonymy. Dolicholus melanostictus (Grisebach) O. Kuntze, Rev. Gen. 3, 2: 62. 1898. Eriosema edule (Grisebach) Burkart, Darwiniana 6: 261. 1943. Eriosema volubile M. Micheli, Gontr. Flor. Parag. 15(1): 36. 1883. Type: PARAGUAY. “L’Assomption, sur le bord des chemins,” Balansa 1553, 15 May 1874 (holotype, G!; holotype fragm., F!; phototypes, TEX!, US!). Rhynchosia nigropunctata S. Watson, Proc. Am. Acad. 14: 408. 1887, pro parte. Type: MEXICO. “Jalisco, Tequila,” E. Palmer 402, Aug-Sep 1886 (holotype, GH!; isotype, US-49302!; paratype, G!, Ervenberg 35 = R. minima). The following isotypes: LE!, NY!, US-1363970! = R. precatoria. Dolicholus nigropunctatus (S. Watson) Rose, Contr. U. S. Natl. Herb. 10: 101. 1906. Eriosema volubile f pube densiore Chodat & Hassler, Bull. Herb. Boiss. II. 4: 905. 1904. Type: PARAGUAY, “in dumeto pr. Valenzuela,” Hassler 6951, Jan 1900 (holotype, G!; isotype, BM!; paratypes, Hassler 8068, BM!, G!, UC!). Rhynchosia rupicola Brandegee, Zoe 5: 202. 1904. Type: MEXICO. Sinaloa, vicinity of Culiacan, Cerro Colorado, Brandegee s n, 1 Nov 1904 (holotype, UC!; isotype, GH!). Dolicholus apoloensis Rusby, Bull. N. Y. Bot. Gard. 6: 515. 1910. Type: BOLIVIA. Apolo, R. S. Williams 97, 22 Feb 1902 (holotype, NY!; isotype, BM!; paratype, Williams 106, NY!). Rhynchosia apoloensis(Rusby) Macbride, Fieldiana Bot. 4:91. 1925. Dolicholus ixodes Standley, Contr. U. S. Natl. Herb. 18: 107. 1916. Type: PANAMA. Vicinity of Penonomé, R. S. Williams 119, 23 Feb-22 Mar 1908 (holotype, US!; isotype, NY!; paratypes, Williams 581, NY!, US!). Rhynchosia ixodes (Standley) Standley, Fieldiana Bot. 4: 214. 1929. Eriosema nigropunctatum Brandegee, Univ. Calif. Publ. Bot. 7: 327. 1920. Type: MEXICO. Vera Cruz: Palmilla, C. A. Purpus 8386, Sep 1919 (isotype, MO!). Rhynchosia pinetorum Standley, Fieldiana Bot. 17: 370. 1937. Type: HONDURAS. Siquatepeque, Dept. Comayagua, Yuncker, Dawson & Youse 5791, 11 Jul 1936 (holotype, F!; isotypes, GH!, K!, MO!). Rhychosia rariflora Standley, Fieldiana Bot. 18: 264. 1937. Type: MEXICO. Chihuahua: Guasaremos, Río Mayo, H. S. Gentry 2883, 28 Sep 1936 (holotype, F!; isotypes, GH!, MO!, S!, UC!, US!). Type. ARGENTINA, “zwischen Clavison und la Ojada, Prov. de Salta,” P. G. Lorentz & G. Hieronymus 1202, 5 Feb 1873 (holotype, B, not seen, probably destroyed; phototypes, G!, MO!, NY!, TEX!, US!; isotype, K!). Local Names, frejol (Peru: San Martín); frijolillo (Guatemala); mielillo (Guatemala); pega-pega (Honduras); poroto capöera, porotillo trepador (Argentina: Misiones). As might be expected by its rather complex synonymy, R. edulis is a variable species. However, the variability is mostly confined to vegetative characters while reproductive characters are remarkably stable. Throughout its extensive range it is found in many diverse habitats. If all the specimens are arranged as a continuum from Arizona through Mexico and Central America to Argentina, one can clearly see a pattern of extreme variation at either end of the range with intermediates in between. Age of the plant, environment and length of the growing season all effect phenotypic expression. Young plants in their first few years of growth have smaller fusiform rootstocks and thinner, shorter stems, while much older plants have extensive branching root systems and thicker, longer stems. If the plants are in open areas or savannas, they are erect, ascending or sprawling but if they occur in forested regions, they are climbing or twining. The stems tend to be mostly perennial in the southern part of its range (especially in permanently moist forests) and the leaves are usually larger, a bit thicker and more deltoid in shape. Pubescence varies as well as the degree of viscidness. Some populations in Mexico and Central America (and in drier, savanna-like areas in general) are glutinous to an exceptional degree and the leaves tend to be smaller and more glandular-punctate. Racemes can vary in size depending, again, on the age of the plant. Older plants produce longer, branching racemes with more flowers than more juvenile plants. Also, the size of individual flowers can vary. In contrast to the large amount of phenotypic plasticity already discussed, characters pertaining to the fruit, seed, calyx and corolla morphology are constant and are, of course, less influenced by the environment and duration of the aboveground portions of the plant. Taxonomists unfamiliar with the wide range of R. edulis and its geographical forms have proposed new species for almost every country throughout its range. Obviously, when a collector or taxonomist was studying a form in one country, he would describe the local variation as new or different without bothering to consult specimens from adjacent countries or other specimens within the total range of the taxon. In most cases, these new names were applied on the basis of only a few collections. Vegetatively, R. edulis most resembles R. minima, R. potosina, R. precatoria and R. caribaea but differs drastically as to reproductive parts. For this reason, R. edulis has been frequently mistakenly identified as these four species. From the list of synonymies it can also be seen that R. edulis has been mistaken for species of Eriosema in a number of cases. This is also true for most of the other species of Rhynchosia in this series and is explained by the similar positioning of the seed, attachment of the funicle and linear shape of the strophiole. The photograph of what is distributed as the holotype (B) of R. edulis is a collection by Lorentz & Hieronymus made in Argentina. It is also designated as the type of R. melanosticta, although Grisebach described them as separate species in the same publication. With the evidence at hand, it seems that he probably changed his mind, considered them synonymous and chose one specimen to serve as the common type. Rhynchosia edulis, appearing before R. melanosticta in the original publication, would be the preferred name. The type collection of R. nigropunctata (Palmer 402) is composed of different elements. The holotype is R. edulis, but some of the isotypes are R. precatoria and the paratype (Ervenberg 35) is R. minima.

Distribution

Distribution. Extreme SE Arizona, Mexico, Central America and South America (Fig. 5). Occuring in diverse habitats: in woods, savannas, thickets, ravines, pastures, along riverbanks, roadsides, dry and moist slopes, in sandy or clay soil at elevations of 150-7300 m.

United States of America North America| Mexico North America| Central America| South America|