Stems scrambling to climbing with tendril-like petioles and leaf-rachises, 4-5 m or more. Leaf blade odd-pinnate, usually 5-foliolate; leaflets deltate to ovate, strongly 3-parted to 3-cleft, proximal leaflets sometimes 3-cleft, 1.5-5.5 × 0.5-4.5 cm, membranous to leathery; segments ovate, deltate, or linear, margins dentate; surfaces pilose, abaxially more densely so. Inflorescences usually axillary, 3-12-flowered simple cymes or compound with central axis or flowers solitary or paired. Flowers unisexual; pedicel slender, (1.1-)1.5-7 cm; sepals wide-spreading, not recurved, white to cream, oblong or elliptic to obovate or oblanceolate, (7-)9-13(-15) mm, abaxially and adaxially pubescent; stamens 40-90; filments glabrous; staminodes 17-35 when present; pistils 35-90. Achenes elliptic to ovate, 3-5 × l.5-2.5 mm, rimmed, short-silky; beak 4-9 cm.
Flowering spring-fall (Mar-Oct). Chaparral, xeric scrub, oak scrub, and grasslands; pastures, fencerows, and other secondary sites; often along streams or on slopes; 0-2200 m; Ariz., Calif., Colo., N.Mex., Okla., Tex.; n Mexico.
As with many other members of the subgenus, the leaves of Clematis drummondii are reputedly used in a poultice to treat irritations of the skin in humans and other animals.
Clematis coahuilensis D. J. Keil is found in central and north-central Mexico in habitats similar to those of C. drummondii ; it is distinguished by ovate, entire to 3-lobed, leathery leaflets.
Wiggins 1964, Kearney and Peebles 1969
Duration: Perennial Nativity: Native Lifeform: Vine General: Scandent and climbing vine with slender woody stems to 10 m long or more, bark tawny or light gray, striate and eventually stringy. Leaves: Petioles 3-8 cm long, sparsely puberulent, coiling like tendrils when in support of vine; leaflets 3-5 (rarely 7), lanceolate to narrowly ovate, 5-15 mm broad, usually less than 5 cm long, divergently 1-3-toothed or entire, grayish-pubescent, often copiously so. Flowers: Cymose panicles, on pedicels 1-2.5 cm long, sepals obovate to narrowly oblanceolate, 1 cm long or less, spreading but soon involute and irregularly reflexed; stamens about 7-8 mm long. Fruits: Achenes, narrowly ovoid, about 4 mm long, pubescent, tails 5-10 cm long, filiform, shining white but turning slightly rusty in drying. Ecology: Climbing over rocks and shrubs below 4,500 ft (1372 m); flowers March-September. Distribution: AZ, CO, NM, TX, s OK; south to c MEX. Notes: Diagnostic for C. drummondi versus C. ligusticifolia involves the longer filiform tail off the achene and the grayish pubescence on the leaves, whereas C. ligusticifolia is glabrous and green. Ethnobotany: Unknown Etymology: Clematis is Greek name given to climbing plants, drummondii is named after Thomas Drummond (1790-1835) a Scottish naturalist. Synonyms: None Editor: SBuckley 2010, FSCoburn 2015