Perennial, Herbs, Stems woody below, or from woody crown or caudex, Taproot present, Nodules present, Stems erect or ascending, Stems less than 1 m tall, Stems solid, Stems or young twigs glabrous or sparsely glabrate, Stems or young twigs sparsely to densely hairy, Leaves alternate, Stipules conspicuous, Stipules green, triangulate to lanceolate or foliaceous, Stipules persistent, Stipules deciduous, Stipules free, Leaves compound, Leaves pinnately 3-foliolate, Leaves odd pinnate, Leaf or leaflet margins entire, Leaflets opposite, Stipels present at base of leaflets, Leaflets 3, Leaves hairy on one or both surfaces, Inflorescences racemes, Inflorescence axillary, Inflorescence terminal, Bracts conspicuously present, Bracts hairy, Bracteoles present, Flowers zygomorphic, Calyx 2-lipped or 2-lobed, Calyx hairy, Petals separate, Corolla papilionaceous, Petals clawed, Petals blue, lavander to purple, or violet, Banner petal ovoid or obovate, Wing petals narrow, oblanceolate to oblong, Wing tips obtuse or rounded, Keel tips obtuse or rounded, not beaked, Stamens 9-10, Stamens diadelphous, 9 united, 1 free, Filaments glabrous, Style terete, Fruit a loment, jointed, separating into articles, Fruit unilocular, Fruit indehiscent, Fruit elongate, straight, Fruit exserted from calyx, Fruit compressed between seeds, Fruit hairy, Fruit 3-10 seeded, Seeds ovoid to rounded in outline, Seeds reniform, Seed surface smooth, Seeds olive, brown, or black.
Kearney and Peebles 1969, Martin and Hutchins 1980
Duration: Perennial Nativity: Native Lifeform: Forb/Herb General: Stems erect to ascending, herbs or small shrubs with a woody caudex, 30 cm or taller. Leaves: Trifoliate leaves, sessile or subsessile leaflets bright green with reticulate veins, lighter green beneath but not glaucous, linear oblong to linear lanceolate, the terminal leaflet lanceolate, 5 times or more as long as wide, all densely strigose on upper surface. Flowers: In terminal or axillary racemes, simple or compound, corolla purple, pink, or white, bracts conspicuous before anthesis, lanceolate or ovate-lanceolate, 4-7 mm long Fruits: Flat loments with several single seeded segments, subsessile or very short stipitate, indehiscent. Ecology: Found usually in dry pine woods from 4,000-8,000 ft (1219-2438 m); flowering July-September. Distribution: AZ, sw NM; south to n MEX. Notes: Distinguished by being an erect-ascending perennial to 0.75 m tall from a thickened woody base(many Desmodiums in the region do not have this combination of characters); the linear-lanceolate leaflets; the ovate to ovate-lanceolate bracts; and the sectioned fruits (loments) with either no stalk (stipe) from the location of the flower, or a small stalk (short-stipitate to sessile). Ethnobotany: There is no specific use recorded for this species, however the genus was used as an infusion to treat vomiting and colds and as a wash for sores. Etymology: Desmodium is from the Greek desmos for chain, which is a reference to the jointed seed pods, while arizonicum means of or from Arizona. Synonyms: Meibomia arizonica Editor: LCrumbacher 2011, FSCoburn 2015