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scorpion ticktrefoil

grassleaf ticktrefoil

Habit Herbs, perennial. Herbs, perennial.
Stems

slender, procumbent or decumbent, 20–100 cm, densely patent uncinate-puberulent and/or inconspicuously pilose.

stiffly erect or ascending, branched at base and appearing clustered, 40–80 cm, glabrescent or sparsely uncinate-puberulent.

Leaves

trifoliolate;

stipules persistent, obliquely ovate, 2–3.5 mm, base auriculate, amplexicaul;

petiole 10–20 mm;

leaflet blades usually ovate to shortly elliptic, rarely narrowly elliptic, apex obtuse, surfaces appressed-pubescent;

terminal blade usually 10–35(–50) × 7–30 mm, length (1.5–)2–3 times width.

unifoliolate;

stipules caducous, narrowly ovate, 3–9 mm;

petiole 10–30 mm;

leaflet blades linear, (40–)70–130 × 2–5 mm, length 10+ times width, apex acute or acuminate, surfaces uncinate-puberulent and sparsely strigose on veins abaxially, uncinate-puberulent adaxially.

Inflorescences

lax-flowered, terminal and axillary, usually unbranched;

rachis densely spreading-pubescent;

primary bracts caducous, narrowly ovate, 1.5–2 mm.

branched or unbranched;

rachis sparsely uncinate-puberulent;

primary bracts ovate, 2–3 mm.

Pedicels

3–10 mm.

10–20 mm, uncinate-puberulent or glabrescent.

Flowers

calyx 1.5–2.5 mm, pilose, tube 1 mm;

abaxial lobes 1.5 mm, lateral lobes 0.7–1 mm;

corolla lavender-pink or reddish purple, banner with yellow spots, 4–5 mm.

calyx 2 mm, puberulent and uncinate-puberulent, tube 0.8 mm;

abaxial lobes 1.2 mm, lateral lobes 1 mm;

corolla ephemeral, purple, 3 mm.

Loments

turgid, straight or curved, linear;

sutures equally shallow-undulate;

connections central, 2/3–3/4 as broad as segments;

segments 5–10, narrowly oblong or narrowly elliptic, 4–5 × 1.5 mm, rugose, not reticulate, symmetrically convex abaxially and adaxially, densely uncinate-pubescent throughout;

stipe 1 mm.

margins slightly involute, sutures equally crenate;

connections central, 1/4 as broad as segments;

segments 3–6, broadly elliptic, (2–)3–3.5 × 2.5–3 mm, convex or rounded abaxially and adaxially, sparsely uncinate-puberulent, sutures moderately uncinate-puberulent;

stipe to 1 mm.

Desmodium scorpiurus

Desmodium gramineum

Phenology Flowering year-round. Flowering late summer–fall.
Habitat Waste places, lawns. Dry woodlands, grass­lands, open hillsides.
Elevation 0–10 m. (0–0 ft.) 1100–1500 m. (3600–4900 ft.)
Distribution
from FNA
FL; Central America; South America; Mexico (Durango, Guerrero, Guanajuato, Jalisco, Michoacán, Oaxaca, Sonora, Veracruz); West Indies [Introduced in North America; introduced also in Asia, Africa, Pacific Islands, Australia]
[BONAP county map]
from FNA
AZ; Mexico (Chihuahua, Colima, Jalisco, Michoacán, Oaxaca, Sinaloa, Sonora, Tamaulipas)
[BONAP county map]
Discussion

In Arizona, Desmodium gramineum is known from Cochise, Pima, Pinal, and Santa Cruz counties.

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

Source FNA vol. 11. FNA vol. 11.
Parent taxa Fabaceae > subfam. Faboideae > Desmodium Fabaceae > subfam. Faboideae > Desmodium
Sibling taxa
D. arizonicum, D. batocaulon, D. canadense, D. canescens, D. cinerascens, D. cuspidatum, D. floridanum, D. grahamii, D. gramineum, D. illinoense, D. incanum, D. intortum, D. laevigatum, D. lindheimeri, D. lineatum, D. marilandicum, D. metcalfei, D. nuttallii, D. ochroleucum, D. paniculatum, D. procumbens, D. psilocarpum, D. psilophyllum, D. retinens, D. rosei, D. rotundifolium, D. scopulorum, D. sessilifolium, D. strictum, D. tenuifolium, D. tortuosum, D. triflorum, D. tweedyi, D. viridiflorum, D. ×humifusum
D. arizonicum, D. batocaulon, D. canadense, D. canescens, D. cinerascens, D. cuspidatum, D. floridanum, D. grahamii, D. illinoense, D. incanum, D. intortum, D. laevigatum, D. lindheimeri, D. lineatum, D. marilandicum, D. metcalfei, D. nuttallii, D. ochroleucum, D. paniculatum, D. procumbens, D. psilocarpum, D. psilophyllum, D. retinens, D. rosei, D. rotundifolium, D. scopulorum, D. scorpiurus, D. sessilifolium, D. strictum, D. tenuifolium, D. tortuosum, D. triflorum, D. tweedyi, D. viridiflorum, D. ×humifusum
Synonyms Hedysarum scorpiurus, Meibomia scorpiurus D. angustifolium var. gramineum, Meibomia graminea
Name authority (Swartz) Poiret in F. Cuvier: Dict. Sci. Nat. ed. 2, 13: 110. (1819) A. Gray: Smithsonian Contr. Knowl. 5(6): 46. (1853)
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