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spike ticktrefoil

Tweedy's ticktrefoil

Habit Herbs, perennial; base woody. Herbs, perennial.
Stems

ascending to erect or sprawling, usually striate, branched, 60–150 cm, sparsely to densely appressed-pilose and sparsely uncinate-pubescent.

ascending or erect, usually striate, angled, 30–100 cm, densely uncinate-puberulent to -pubescent and sparsely glutinous-pilose.

Leaves

trifoliolate;

stipules caducous, narrowly ovate-deltate, 3–4 mm;

petioles 20–40 mm proximally, 8–20 mm distally;

leaflet blades narrowly elliptic-oblong, apex obtuse, lateral veins prominent, reaching margin, margin flat, surfaces subappressed-villous abaxially, glabrescent adaxially;

terminal blade 25–70 × 15–25 mm, length 2–3 times width.

trifoliolate;

stipules persistent, ovate, 7.5–14.5 mm;

petiole 40–90 mm;

leaflet blades narrowly ovate to ovate or broadly ovate, thick, leathery, apex acute, usually pale-blotched along midrib adaxially, surfaces uncinate-puberulent to -pubescent and villous;

terminal blade 40–120 × 20–66 mm, length 2 times width.

Inflorescences

branched or unbranched and elongate when terminal, or unbranched from distal axils;

rachis closely appressed-pubescent and patent uncinate-puberulent;

primary bracts caducous, narrowly ovate, 3–5 mm.

branched or unbranched;

rachis densely uncinate-puberulent to -pubescent and glutinous-villous;

primary bracts ovate to broadly ovate, 7–10 mm.

Pedicels

8–10 mm.

8–25 mm, patent uncinate-pubescent and pilose.

Flowers

calyx 4 mm, densely uncinate-puberulent, tube 2 mm;

abaxial lobes 2 mm, lateral lobes 1 mm;

corolla purple, 8–11 mm.

calyx 3–5 mm, puberulent and pubescent, ± glutinous, tube 1.2–1.5 mm;

abaxial lobes 2.5–4 mm, lateral lobes 1.5 mm;

corolla white, 7–8 mm.

Loments

sutures crenate;

connections central, 1/3 as broad as segments;

segments 3–8, semiorbiculate, 5–7 × 4–5 mm, rounded abaxially, convex adaxially, villosulous or pubescent and uncinate-puberulent throughout;

stipe 2–5 mm.

sutures nearly equally crenate;

connections adaxial, 1/4 as broad as segments;

segments (2 or)3–5(or 6), subrhombic, 6–8 × 4 mm, obtusely angled abaxially, somewhat angled adaxially, densely uncinate-pubescent throughout;

stipe 2–4 mm.

Desmodium cinerascens

Desmodium tweedyi

Phenology Flowering late summer–fall. Flowering early summer.
Habitat Open, dry slopes, with oak or pine, canyons, washes, roadsides. Woodlands near creeks, usually calcareous soils.
Elevation 1200–1800 m. (3900–5900 ft.) 200–800 m. (700–2600 ft.)
Distribution
from FNA
AZ; Mexico (Chihuahua, Durango, Nayarit, Sinaloa, Sonora)
[BONAP county map]
from FNA
OK; TX
[BONAP county map]
Discussion

Desmodium cinerascens is known in the flora area from the south-central and southeastern areas of Arizona.

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

Desmodium tweedyi is known from the Edwards Plateau area and north-central Texas northward to central Oklahoma.

(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. 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. scorpiurus, 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. psilocarpum, D. psilophyllum, D. retinens, D. rosei, D. rotundifolium, D. scopulorum, D. scorpiurus, D. sessilifolium, D. strictum, D. tenuifolium, D. tortuosum, D. triflorum, D. viridiflorum, D. ×humifusum
Synonyms Meibomia cinerascens Meibomia tweedyi
Name authority A. Gray: Smithsonian Contr. Knowl. 5(6): 48. (1853) Britton: Trans. New York Acad. Sci. 9: 183. (1890)
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