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scorpion ticktrefoil

Santa Cruz Island ticktrefoil

Habit Herbs, perennial. Herbs or shrubs, perennial.
Stems

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

erect or ascending, branched, 40–100 cm, slightly uncinate-pubescent and pilose or glabrescent.

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.

trifoliolate;

stipules mostly persistent, broadly ovate, 4–10 mm, base subamplexicaul;

petiole 30–40 mm;

leaflet blades broadly ovate-elliptic or ovate to narrowly ovate, apex acute, surfaces uncinate-puberulent;

terminal blade 20–70(–100) × 10–20(–50) mm, length 1.8–2 times width.

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 bulbous-villous and uncinate-puberulent;

primary bracts caducous, subulate, 1 mm.

Pedicels

3–10 mm.

10–20 mm, patent uncinate-pubescent.

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 1.5–2 mm, pilose and uncinate-puberulent, tube 0.8 mm;

abaxial lobes 1 mm, lateral lobes 0.8–1 mm;

corolla pink-purple, fading greenish, 4–5 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.

sutures subequally deeply crenate;

connections central, 1/8–1/7 as broad as segments;

segments 3–6, rounded, 6–10 × 5–7 mm, rounded, sparsely pubescent, at least on sutures;

stipe 1(–2) mm.

Desmodium scorpiurus

Desmodium psilocarpum

Phenology Flowering year-round. Flowering late summer–fall.
Habitat Waste places, lawns. Woodland, grasslands, canyon slopes, streamsides.
Elevation 0–10 m. (0–0 ft.) 1000–2000 m. (3300–6600 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; NM; Mexico (Chihuahua, Nuevo León, Sonora, Tamaulipas)
[BONAP county map]
Discussion

Desmodium psilocarpum is known in the flora area from southern Arizona and adjacent southwestern New Mexico.

(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. 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. 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 Meibomia psilocarpa
Name authority (Swartz) Poiret in F. Cuvier: Dict. Sci. Nat. ed. 2, 13: 110. (1819) A. Gray: Smithsonian Contr. Knowl. 5(6): 48. (1853)
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