Vigna longifolia, (Benth.) Verdc.

Delgado-Salinas, Alfonso, Lavin, Matt, Snak, Cristiane & Lewis, Gwilym P., 2022, Systematics of Vigna subgenus Lasiospron (Leguminosae: Papilionoideae: Phaseolinae), Systematic Botany (Basel, Switzerland) 47 (1), pp. 97-124 : 111-113

3. VIGNA LONGIFOLIA (Benth.) Verdc. , in Kew Bulletin 24: 541 (1970). Phaseolus longifolius Benth., Comm. Legum. Gen. : 75 (1837). TYPE: BRAZIL. “ad Brasilia”, Schott s.n. (holotype: W!). Figure 8 .

Phaseolus schottii var. longifolius f. intermedius Hassl., Candollea 1: 463. 1923. TYPE: PARAGUAY. Chaco. Hassler 2769 (G, not seen); J€ orgensen 2959 (lectotype: G!, designated here; MO!, US! 5 V. longifolia ) synon. nov. Syntypes Rojas 2917 (SI! 5 V. longifolia ). ARGENTINA. J€ orgensen 2951 (SI! 5 V. longifolia ).

Phaseolus schottii var. longifolius f. grandiflorus Hassl., Candollea 1: 464. 1923. TYPE: PARAGUAY. “in Paraguaria septentrionales”, 1901–1902, E. Hassler 7320 (lectotype: G!, designated here; isolectotypes: BM!, F!, G!, GH!, MO!, NY!), synon. nov.

Perennial or annual (?), scrambling or climbing vines up to 3 m, with foliage and reproductive parts covered with minute glandular hairs, and a sparse or dense pubescence. Stems rhizomatous, hollow, slightly woody at base, often with adventitious roots, sparsely strigose, with yellow, retrorse hairs less than 1 mm long. Leaves with stipules narrowly-lanceolate, unequally bilobed, upper portion 4–6 3 1–2 mm, 5–6-veined, not reflexed, persistent; lower portion ca. 2 mm long, sparsely pilose; stipels oblong or triangular, 1.5–2 mm long, subequal in length to petiolules, glabrous except for minute glandular trichomes; petioles 4–10 cm long, covered with retrorse hairs, rachis considerably shorter, 5–20 mm long, with some antrorsely appressed hairs on the adaxial side, canaliculate; leaflets entire, ovate to narrowly ovate or lanceolate, acute or acuminate at apex, often with raised veins below, membranaceous to chartaceous, sparsely to densely strigose, terminal leaflet 9–15 3 1.3–5.5 cm, lateral leaflets 7–11 3 2–5.5 cm. Inflorescences up to 35 cm long, peduncles 14–32 cm long, covered with short retrorse hairs, densely strigose distally; rachis 1.5–3 cm long, with 2–4 swollen ovoid nodes, these 2–4 mm long, with 4–6 alternate orifices, flowers clustered distally; primary bracts, caducous, secondary bracts ca. 6 mm long, caducous; bracteoles mostly persistent at anthesis, 6–10 mm long, longer than calyx tube; pedicels shorter than calyx tube, longer and twisting in fruit, covered distally with retrorse, straight hairs; calyx campanulate, sparsely strigose at the base, glabrous distally, 4–5 3 2–3 mm, upper teeth slightly divided, narrow and acute, not forming a lip, other teeth triangular, subequal, 1.5–2 mm long, lower tooth slightly longer than lateral teeth. Flowers golden yellow, ca. 2.5 cm long, standard petal asymmetric, broadly ovate, ca. 2 3 ca. 2.5 cm, bilobed at apex, with two parallel, thick callosities on the lamina above the point of folding, and two fleshy auricles above a short claw; wing petals longer than keel, with an obovate lamina, ca. 2.5 3 ca. 1.5 cm, with an auricle at base, claw ca. 3 mm long; keel distinctly beaked, coiled ca. 360, almost forming a complete circle, ca. 1.5 cm above the wing, with transverse pockets above the claws, claws ca. 4 mm long, fused to staminal tube; androecium ca. 3.5 cm long, staminal tube ca. 2.5 cm long, vexillary stamen with a basal appendage; anthers oblong-ovate, ca. 1 mm long, basifixed to sub-basifixed to filaments; pollen grains triporate, with a coarsely reticulate exine; ovary straight, with a basal nectary disc ca. 1 mm long, ovules 12–14, style with a tenuous lower part, upper part thickened and cylindrical, curved, pollen brush ca. 8 mm long, with long spreading hairs, produced beyond the stigma to form a short hook; stigma transversally-ovate, laterally placed, surrounded by short cilia. Fruit patent, oblong to slightly falcate, sub-cylindrical, valves thick-walled, not constricted between the seeds, turning dark brown or black at maturity, (4–) 6–8 cm long, 5–6 mm wide, elastically dehiscent, densely strigose, with yellow and white, straight hairs, beak straight, 5–7 mm long. Seeds globose to D- shaped, ca. 3 3 ca. 4 mm, surface smooth, testa light brown, mottled darker brown, hilum oblong, as long as seed width, rim-aril prominent, covered by an epihilum, aril consistently present, hippocrepiform, cartilaginous with white-banded crenate margins, mostly surrounding the hilum. Chromosome number: 2 n 5 22 ( Mercado-Ruaro and Delgado-Salinas 1996). Figure 8 .

Distribution and Habitat —Southern Mexico (Campeche, Chiapas, Tabasco, Veracruz), Central America ( Guatemala, El Salvador, Costa Rica, Panama) and in South America, Amazon River basin, and Amazonian savannas, Restinga Atlantic Forest and in the Paraguay-Parana fluvial system ( Argentina, Bolivia, Brazil, Colombia, Ecuador, Paraguay, Peru, Venezuela). Although widely distributed, this species has not to our knowledge been collected in Guyana, French Guiana, and Suriname. Vigna longifolia , as well as V. lasiocarpa , have been collected in the Pacific lowlands of Ecuador (Guayas Province), the most western location for species of V. subg. Lasiospron in South America. This species also has one of the most southern occurrences of a V. subg. Lasiospron species in northeastern Argentina ( Fig. 3 ). Vigna longifolia generally inhabits seasonal or permanently flooded plains or savannah-type grasslands, and is sometimes reported sprawling on floating vegetation. It also grows in old rice fields; altitudinal range from 0– 600 m. Flowering and fruiting throughout the year.

Etymology —The species epithet longifolia refers to the long, narrow leaflets.

Vernacular Names —“Baul ch’ o” (E. Ucan 1607); “feij ~ ao bravo” ( Melo 3352); “Siratro de Agua” (Lock 83/66).

Uses —The species is relished by livestock, and its seeds are eaten by birds (Pott and Pott 1994).

Representative Specimens Examined —See Appendix 1 for complete list. Argentina. — CHACO PROVINCE: Colonia Benıtez, without date, A. G. Schulz 10328 (G). Bolivia. — EL BENI: Trinidad, Jan 1965, O. Braun 11 (US). Brazil. — AMAZONAS: Alenquer, Margem do Rio Amazonas, 30 May 2014, C. Snak et al. 1216 (HUEFS). Colombia. — AMAZONAS: Rıo Lontoyacu, 2 Oct 1946, R. E. Schultes 46–173 (US). Costa Rica. Guanacaste Province, Canton Bagaces P.N. Palo Verde, valle de Tempique, Sector Catalina, La Espuela y el area administrativa de Palo Verde, 10 21'0 99 N, 85 21'0 99 W, 10 m, 22 Sep 1994, U. Chavarrıa 1047 (K). Ecuador. — GUAYAS: Estacion Psicıcola Santa Priscila, Est. 3, 2 23 9 0”N, 79 46 9 W, 5 m, 20 May 2000, X. Cornejo and C. Bonifaz 7049 K). El Salvador. — AHUACHAPÁN: A.P. Santa Rita, ruta 7, La Laguna, 13 48 9 0 99 N, 90 4 9 0 99 W, 20 m, 12 Apr 2004, J. M. Rosales 2365 (MEXU). Guatemala. Depto. Jutiapa, potreros between Trapiche Vargas and Asuncion Mita, 500–600 m, 15 Nov 1939, J. A. Steyermark 31881 (F). Mexico. — CAMPECHE: Hopelchen District, a 2.2 km al ENE de Chun-Ek, 19 11 9 42 99 N, 89 10 9 25 99 W, 90 m, 26 Aug 2005, D. Alvarez 11670 (MEXU). Panama. — CANAL ZONE: vicinity of Frijoles, 3 Mar 1923, C. V. Piper 5164 (US). Paraguay. — CHACO: campos bajos estero Estancia Loma Para, Apr 1917, T. Rojas 2917 (SI). Peru. — LORETO: Lower Rıo Nanay, May-Jun 1929, Ll. Williams 555 (US). Venezuela. — APURE: Payarita, entre San Fernando y Achaguas, Bajo Apure, 12 Aug 1972, M. Ramia 4852 (VEN).

Notes — Bentham (1859) considered Phaseolus longifolius and P. schottii as conspecific, placing the latter as a synonym of the former. As mentioned above, Hassler (1923) recognised P. schottii published earlier in Bentham’ s (1837) treatment, and he published four varieties, P. schottii var genuinus , P. schottii var. campestris , P. schottii var. longifolia , and P. schottii var. tucumanensis . In our treatment, the typical variety is discussed under Vigna schottii , and varieties campestris and tucumanensis under V. juruana .

In more recent classifications (Verdcourt 1970; Marechal et al. 1978), Vigna longifolia included three of the six species here considered as part of V. subg. Lasiospron . The species V. diffusa , V. schottii and for some time even V. trichocarpa were considered as synonyms of this distinctive species. Vigna longifolia is distinguished from the other V. subg. Lasiospron species by a combination of features, including its bi-auriculate stipules with a long, narrowly triangular upper portion, up to 6 mm long, and lanceolate leaflets, up to 15 cm long. Its flowers are approximately 2 cm long, with a conspicuous hooked style tip. The long-tapering pods with thick-walled valves have seeds each with a conspicuous white aril. Seeds with cartilaginous white arils are also consistently present in V. lasiocarpa .

Figures

FIG. 8. Illustration of Vigna longifolia. A. Habit, natural size. A1. Portion of stem. A2. Portion of petiole. B. Stipules, only a portion of indumentum shown for clarity (3 6). C. Leaflets showing variation in shape (natural size). C1. Detail of vein. D. Extrafloral nectaries on inflorescence node (3 6). E. Flower bud (pre-anthesis), including bracteoles, indicated by arrow (3 3). F. Calyx opened out, external surface (3 3). G. Standard petal, ventral surface (3 0.5). G1. Standard petal, external surface (3 1). G2. Standard petal inner surface showing thickenings and auricles (3 6). H. Wing petal (3 3). I. Keel petals, drawn from young flower (3 3). J. Staminal tube with free vexillary stamen (3 3). K. Gynoecium (3 3). L. Fruits, natural size. L1. Twisted pedicel at base of fruit. M. Seed (3 6). Drawn from Barbosa & Silva 1927 (habit and flower dissection); Herbarium Lehmannianum 8757 (fruit and seed). Illustration by Pat Halliday.

FIG. 3. Geographic distributions of the six species of Vigna subg. Lasiospron, which are ordered, top to bottom, by mean latitude. Filled circles indicate species with amphi-Atlantic distributions.