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Chihuahuan snoutbean

American snoutbean

Habit Herbs.
Stems

erect, suberect, decumbent, procumbent, or twining, viscid, hirsute, hairs yellowish.

procumbent, trailing, or twining, villous or villosulous, hairs silvery, spreading.

Leaves

trifoliolate;

stipules persistent, linear to narrowly lanceolate, 3–9 × 0.5–1.5 mm, apex acute to acuminate, surfaces hirsute;

petiole 15–55 mm, hirsute;

leaflet blades lanceolate to obovate-oblong or ovate-deltate, 15–70 × 10–60 mm, membranous or leathery, gland-dotted, often viscid, base obtuse to rounded or truncate, margins ciliate, slightly revolute, apex acute to acuminate, surfaces strongly reticulate and sparsely to densely hirsute abaxially, strigulose to strigose adaxially.

usually unifoliolate, distalmost rarely trifoliolate;

stipules persistent, ovate-lanceolate, 2–5 × 1–2.5 mm, apex acuminate;

petiole 10–45 mm, villosulous;

leaflet blades suborbiculate to reniform, 15–40 × 20–55 mm, leathery, gland-dotted, base cordate, apex broadly rounded, surfaces villosulous abaxially, rugose and finely strigose adaxially.

Inflorescences

racemes, equal to or longer than leaves, 2.5–20 cm.

racemes, shorter than leaves, 1.5–5 cm.

Pedicels

1–3 mm.

2–5 mm.

Flowers

calyx 4–7 mm, hirsute, tube 1.5–2 mm, lobes lanceolate, laterals 2–2.5 mm, lengths to 2.5 times tube, adaxials 1.5–3 mm;

corolla yellow, striped reddish brown or purple;

banner widely ovate to obovate, 7–10 × 4–5 mm, slightly apiculate, hirtellous and gland-dotted;

wings narrowly oblong, 6.5–9 × 1.5–2 mm, gland-dotted, puberulent apically;

keel 6.5–9 × 2–3 mm, glabrous;

stamens 6–9 mm.

calyx 7–13 mm, villosulous, tube 1.5–2 mm, lobes lanceolate, laterals 6–10 mm, adaxials 2–4 mm;

corolla yellow, often tinged brown;

banner obovate, 8.5–10 × 6.5–7.5 mm, emarginate, puberulous;

wings narrowly oblong, 6.5–7.7 × 2–2.5 mm, glabrous;

keel 8–9 × 3–3.5 mm, glabrous;

stamens 7.5–8.5 mm.

Legumes

oblong-ovoid, compressed, 16–26 × 6–8 mm, often viscid, long-hirsute to puberulent, hairs intermixed, glabrescent.

oblong-ovoid, compressed, 10–15 × 5–8 mm, villosulous.

Seeds

greenish brown or mottled, widely ovoid to subglobose, compressed, 4–5 × 3–4 mm.

brown, black, or mottled, subglobose, compressed, 3–4 × 3–3.5 mm.

Vines

, herbaceous.

2n

= 22.

Rhynchosia edulis

Rhynchosia americana

Phenology Flowering spring–summer. Flowering spring–summer.
Habitat Sandy or clay soils of woodland, thickets, ravines, pastures, stream banks, roadsides. Sandy soils, prairies, fields, oak woodlands, roadsides, sand dunes.
Elevation 800–1500 m. (2600–4900 ft.) 0–300 m. (0–1000 ft.)
Distribution
from FNA
AZ; Central America; South America; Mexico (Chiapas, Durango, Guerrero, Jalisco, Michoacán, Nayarit, San Luis Potosí, Sonora, Veracruz)
[BONAP county map]
from FNA
TX; Mexico (Chiapas, Durango, San Luis Potosí, Sinaloa, Tamaulipas, Veracruz)
[BONAP county map]
Discussion

In Arizona, Rhynchosia edulis is found only in Santa Cruz County.

Dolicholus melanostictus (Grisebach) Kuntze is an illegitimate name that pertains here.

(Discussion copyrighted by Flora of North America; reprinted with permission.)

In Texas, Rhynchosia americana occurs in coastal and southern counties.

(Discussion copyrighted by Flora of North America; reprinted with permission.)

Source FNA vol. 11. FNA vol. 11.
Parent taxa Fabaceae > subfam. Faboideae > Rhynchosia Fabaceae > subfam. Faboideae > Rhynchosia
Sibling taxa
R. americana, R. cinerea, R. cytisoides, R. difformis, R. latifolia, R. michauxii, R. minima, R. parvifolia, R. precatoria, R. reniformis, R. swartzii, R. texana, R. tomentosa
R. cinerea, R. cytisoides, R. difformis, R. edulis, R. latifolia, R. michauxii, R. minima, R. parvifolia, R. precatoria, R. reniformis, R. swartzii, R. texana, R. tomentosa
Synonyms Dolicholus apoloensis, D. ixodes, Eriosema edule, E. nigropunctatum, E. volubile, R. apoloensis, R. ixodes, R. melanosticta, R. nigropunctata, R. pinetorum, R. rariflora, R. rupicola Lathyrus americanus, Glycine menispermoides, Phaseolus menispermoideus, R. menispermoidea
Name authority Grisebach: Abh. Königl. Ges. Wiss. Göttingen 19: 123. (1874) (Miller) Metz: Catholic Univ. Amer., Biol. Ser. 16: 126. (1934)
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