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Arizona tick trefoil

Sonoran ticktrefoil

Habit Herbs, perennial. Herbs, annual.
Stems

erect or ascending, usually striate, sparsely branched, 20–80 cm, pubescent.

erect or ascending, usually striate, branched, 10–80 cm, pubescent.

Leaves

trifoliolate;

stipules caducous, narrowly ovate, 6–8 mm;

petiole 1–5 mm;

leaflet blades narrowly oblong-elliptic to linear, apex acute, surfaces villosulous;

terminal blade 40–60 × 4–10 mm, length 3.5–10 times width.

trifoliolate;

stipules caducous, narrowly deltate to subulate, 3–4 mm;

petiole 10–40 mm;

leaflet blades narrowly ovate to ovate, apex acute to acuminate, surfaces densely uncinate-puberulent and pilose abaxially, uncinate-puberulent and pilose adaxially;

terminal blade 20–100 × 7–25 mm, length 4–8 or 2–3 times width.

Inflorescences

usually unbranched;

rachis uncinate-puberulent;

primary bracts caducous, broadly ovate, 4.5–5.5 mm.

branched or unbranched;

rachis uncinate-puberulent;

primary bracts narrowly ovate, 1.4–2.6 mm.

Pedicels

8–15 mm.

5–15 mm.

Flowers

calyx 3 mm, uncinate-puberulent, lobes pubescent, tube 1.2 mm;

abaxial lobes 2 mm, lateral lobes 1.5 mm;

corolla blue-purple, 5–6 mm.

calyx 1–1.5 mm, puberulent, tube 0.5 mm;

abaxial lobes 1–1.5 mm, lateral lobes longer than tube;

corolla pink, drying greenish yellow, 3–4 mm.

Loments

sutures undulate abaxially, crenate adaxially;

connections adaxial, 1/3 as broad as segments;

segments (2 or)3–5, semiorbiculate, 4–5(–6) × 4 mm, rounded abaxially, convex adaxially, uncinate-puberulent;

stipe 1–2 mm.

sutures subequally incised, spirally arranged between young segments when young;

connections adaxial, 1/8 as broad as segments;

segments 2–4, proximal segments subrhombic, 4–6 × 2.5–3.5 mm, irregularly involute, uncinate-pubescent, distal segment semiorbiculate or broadly deltate, much larger than proximal segments, not contorted, 7–10 × 4–5 mm, glabrous, sutures uncinate-puberulent;

stipe 1 mm.

2n

= 22.

Desmodium arizonicum

Desmodium scopulorum

Phenology Flowering summer–fall. Flowering fall.
Habitat Oak-juniper or pine wood­lands, canyons, roadsides. Open grassy slopes, oak-pine wood­lands.
Elevation 1700–2500 m. (5600–8200 ft.) 800–1800 m. (2600–5900 ft.)
Distribution
from FNA
AZ; NM; Mexico (Baja California, Chihuahua, Sinaloa, Sonora, Tamaulipas)
[WildflowerSearch map]
[BONAP county map]
from FNA
AZ; Mexico (Baja California Sur, Sinaloa, Sonora)
[BONAP county map]
Discussion

In the flora area, Desmodium arizonicum is known from southeastern Arizona and adjacent New Mexico.

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

In the flora area, Desmodium scopulorum is known from Pima 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. 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. 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. scorpiurus, D. sessilifolium, D. strictum, D. tenuifolium, D. tortuosum, D. triflorum, D. tweedyi, D. viridiflorum, D. ×humifusum
Synonyms Meibomia arizonica D. wigginsii, Meibomia scopulorum
Name authority S. Watson: Proc. Amer. Acad. Arts 20: 363. (1885) S. Watson: Proc. Amer. Acad. Arts 24: 47. (1889)
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