Dalea onobrychis

  • Title

    Dalea onobrychis

  • Authors

    Rupert C. Barneby

  • Scientific Name

    Dalea onobrychis DC.

  • Description

    84.  Dalea onobrychis DeCandolle

    (Plate LXXXV)

    Suffruticose or perhaps weakly shrubby in age, 6-15 dm tall, the diffuse or ascending, castaneous or livid stems paniculately branching distally, at least when young puberulent or pilosulous with weak subappressed and ascending hairs up to 0.3-0.5 (0.6) mm long, and charged with scattered hemispherical or subglobose (grainlike) warts, the foliage green but the leaflets at least puberulent beneath, smooth above, charged beneath with raised dots; leaf-spurs 0.8-2 mm long; stipules linear-acuminate, (2) 3-6 mm long; intrapetiolular glands 2, small but prominent; post-petiolular glands prominent, hemispherical, livid-castaneous; leaves mostly short-petioled, the main cauline ones 4-7 (8) cm long, with slender, narrowly margined rachis and 5-8 (9) pairs of obovate, oblong-obovate, or -elliptic, obtuse and gland-mucronulate, or apicu- late, or weakly emarginate, flat, dorsally slender-carinate leaflets 6-16 (some at least (7) 9) mm long, the terminal one stalked; peduncles mostly leaf-opposed, usually much longer than the associated leaf, the lowest of each primary axis (0.7) 1-2 dm, rarely only 3-7 (10) cm long, those terminal to leafy lateral branchlets, if present, always shorter; spikes many-flowered, dense but not conelike, ovoid-acuminate becoming a little looser and cylindroid, without petals (8) 9-11 mm, the densely villosulous axis becoming 3.5-8 cm, rarely not elongating but capitate and only 0.5-1.5 cm long; bracts deciduous by full anthesis, but sometimes held fast between crowded calyces, 4-6 mm long, the ovate navicular, thinly papery body 3.2-4 mm long, in profile (1.3) 1.6-2 mm wide, densely pilosulous except toward the membranous margins, inconspicuously gland-charged dorsally, abruptly contracted into a linear, often incurved, livid tail (1) 1.3-1.9 mm long; calyx 3.7-4.8 mm long, pilosulous from base upward with straight ascending hairs up to 0.6-0.9 mm long, or sometimes glabrate on the abaxial side, the tube 2.7-3.3 mm long, its orifice only little oblique, the ribs livid, subfiliform, the intervals charged with 1 row of ± 3-5 small, livid or golden glands, the teeth deltate to triangular-apiculate, somewhat unequal, the dorsal one longest and narrowest, 1-1.8 mm long (1.2-2.2 mm shorter than tube), the ventral pair broadest and shortest; petals bicolored, the gland-tipped and -sprinkled banner white at middle or distally, rubescent, the epistemonous ones either bright blue or amethystine-purple, perched much below middle of androecium (2-3 mm above hypanthium), the keel usually gland-tipped; banner 6.8-7.5 mm long, the claw 3.8-4.5 mm, the blade 4-4.4 mm long, 4.8-5 mm wide, open at base but the basal lobes incurved and adherent to form lateral pockets; wings 5.8-7.1 mm long, the claw 1.3-1.6 mm, the blade 5-5.6 mm long, 2.8-3.4 mm wide; keel 6.5-8.4 mm long, the claws 1.6-2.1 mm, the blades 5.2-6.8 mm long, 3.4-4 mm wide; androecium 8-9.5 mm long, the longer filaments free for 2.4-3.1 mm, the connective gland-tipped, the anthers 0.65-0.8 mm long. — Collections: 20 (o).

    Open rocky and grassy hillsides, (450) 800-3250 m, widely but interruptedly dispersed along the w. slope of the Peruvian Andes from Cajamarca (prov. Contumaza) to Arequipa (prov. Condesuyos).— Flowering March to August, n.-ward perhaps indefinitely. —Representative: Cajamarca. Contumaza: Sagastegui 3673 (US). La Libertad. Trujillo: Chrestowski 1-18 (NY). Lima. Canta: Ferreyra 1983 ( US); Mathews 549 (K, p.p., NY). Lima: Ferreyra 2844 (US). Huarochiri: Killip & Smith 21,702 (F, NY, US); Hutchinson 601 (K, UC, US); Ferreyra 5421, 6962 (US); Goodspeed et al. 11,515 (K, UC). Arequipa. Condesuyos: Stafford 1209 (K).

    Dalea onobrychis (resembling sainfoin) DC., Prod. 2: 247. 1825 ("Onobrychis").— "...in Peruvia...(v. s. comm, a cl. Lagasca)." — Holotypus, G-DC! — Parosela onobrychis (DC.) Macbr., Field Mus., Bot. 4: 108. 1927.

    The range of D. onobrychis lies wholly within that of the related and in many respects similar D. cylindrica; they are often exactly sympatric and subject to similar types of variation and as a consequence lack ideal sets of dependable differential characters. Along the Oroya highway east of Lima the two species, D. cylindrica represented by typical var. cylindrica, in this region with pale yellow petals more or less amethyst tinged, and D. onobrychis, with vivid blue or blue-violet petals, are most readily distinguished by flower- color, but a more important character is found in the bracts, those of D. onobrychis deciduous, submembranous, densely hairy externally, those of D. cylindrica persistent, firm, glabrous. Elsewhere, however, D. onobrychis may have amethyst- or reddish-purple epistemonous petals, shades not detectably different, at least in dried material, from some encountered in D. cylindrica sens, lat., and the bract remains the most valuable diagnostic feature. At its southern limit in Arequipa D. onobrychis closely approaches D. pennellianus, the only other perennial dalea known to occur on the Pacific slope of the Peruvian Andes. This also has deciduous bracts, but is a smaller, prostrate herb with looser spikes of longer calyces, in practice easily recognized though once again not strongly characterized.

    The typus of D. onobrychis was sent to DeCandolle without any more precise locality than "Peru." We know, however that the species had been collected by Dombey about 1788-9 (no. 855, F, P) and was readily accessible to anyone travelling the trans-Andean highway from Lima to Tarma. The plant so closely resembles modern collections from this region that it is reasonable to suppose that it came from thereabouts, even though the actual collector cannot now be ascertained. In the Department of Lima the peduncle is characteristically elongate, the first one of each primary cauline axis being more than twice the length of its subtending leaf, generally 1-2 dm long; and the spike is ovoid in bud becoming at full anthesis and later oblong or cylindric. The same spike but borne on short peduncles characterizes the one known gathering from Arequipa (cited, supra); and in Cajamarca a curious, perhaps distinct form is known in which the short peduncle bears a greatly condensed and headlike spike only 0.5-2 cm long. Of this latter I have seen only one specimen in bud (Sagastegui 3773, US), and one in flower ("northern Peru", Stordy, K); they are connected to more typical D. onobrychis by another gathering (Sagastegui 3673 from Contumaza) with an open spike up to at least 6 cm long. As nothing is known of the possible effects of environment and season on the rather diverse aspect of the material cited, it seems prudent to include them for the present in an inclusive concept of an apparently polymorphic species.