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Arizona tick trefoil

San Pedro tick trefoil

Habit Herbs, perennial. Herbs, perennial.
Stems

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

decumbent or decumbent-assurgent, branched, 30–120 cm, densely uncinate-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.

tri-foliolate;

stipules caducous, narrowly ovate, 5+ mm;

petiole 20–30 mm;

leaflet blades ovate-elliptic to narrowly so, apex acute to obtuse, surfaces densely appressed-pubescent abaxially, sparsely so adaxially;

terminal blade (20–)35–60 × 8–10(–15) mm, length 2.5–4 times width.

Inflorescences

usually unbranched;

rachis uncinate-puberulent;

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

axillary and terminal, branched or unbranched;

rachis patent uncinate-puberulent to pubescent;

primary bracts closely imbricate before anthesis, caducous, ovate, 5 mm.

Pedicels

8–15 mm.

5–10 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 3–4 mm, sparsely pubescent, tube 1 mm;

abaxial lobes 3 mm, lateral lobes 2 mm;

corolla pink or purple to blue, 7–9 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 undulate abaxially, sinuate adaxially;

connections adaxial, 1/4–1/3 as broad as segments;

segments 4–7, semiorbiculate, 3–5 × 3–3.5 mm, rounded abaxially, slightly convex adaxially, glabrous or sparsely uncinate-puberulent throughout;

stipe 1–2 mm.

2n

= 22.

Desmodium arizonicum

Desmodium batocaulon

Phenology Flowering summer–fall. Flowering late summer–fall.
Habitat Oak-juniper or pine wood­lands, canyons, roadsides. Dry, rocky woodlands, pine or oak-juniper woodlands, canyons, roadsides.
Elevation 1700–2500 m. (5600–8200 ft.) 1200–2100 m. (3900–6900 ft.)
Distribution
from FNA
AZ; NM; Mexico (Baja California, Chihuahua, Sinaloa, Sonora, Tamaulipas)
[WildflowerSearch map]
[BONAP county map]
from FNA
AZ; NM; Mexico (Baja California, Baja California Sur, Chihuahua, Guerrero, Sonora, Tamaulipas, Zacatecas)
[WildflowerSearch map]
[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 batocaulon is known from southeastern Arizona and 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. 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. 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
Synonyms Meibomia arizonica Meibomia batocaulos
Name authority S. Watson: Proc. Amer. Acad. Arts 20: 363. (1885) A. Gray: Smithsonian Contr. Knowl. 5(6): 47. (1853)
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