Dalea piptostegia

  • Title

    Dalea piptostegia

  • Authors

    Rupert C. Barneby

  • Scientific Name

    Dalea piptostegia Barneby

  • Description

    107.  Dalea piptostegia Barneby

    (Plate XCVIII)

    Low, leafy, abundantly floriferous shrubs of rounded outline, in aspect resembling D. dorycnioides, up to 7 dm tall and as wide or wider, with many repeatedly branching, castaneous or purplish (when old, brown and furrowed), densely verruculose stems, variable in pubescence, either densely pilosulous-tomentulose with extremely fine spreading and ascending hairs up to 0.1-0.2 mm long, the herbage then gray and the leaflets subequally pubescent both sides, or the vesture reduced to an inconspicuous remnant, the stems then glabrous or nearly so and the foliage green, the leaflets (always punctate beneath) glabrous above, puberulent dorsally; leaf-spurs 0.5-0.9 mm long; stipules lance-subulate, 1-2.4 mm long, papery or becoming so, reddish; intra- petiolular glands small, subimmersed; post-petiolular glands prominent, puberulent; leaves very shortly petioled, the main cauline ones (readily deciduous) 1.5-2.5 cm long, with 3-4 (5) pairs of oblong-oblanceolate, emarginate, flat or loosely folded leaflets 4-8 mm long, the terminal one sessile or almost so, the leaves of short-shoots present in almost all primary axils shorter, with 2-4 pairs of smaller leaflets; peduncles at first leaf-opposed and 2-5.5 (7) cm long, the later ones terminal to branchlets and 0.5-2.5 cm long, all prominently verruculose; spikes moderately dense, at first ovoid, becoming oblong in outline, the flowers (pressed) falling in 3-4 ranks but concealing the densely pilosulous axis, this finally in primary spikes 2-3 (4) cm long, in later spikes shorter; bracts (except sometimes the lowest of each spike) readily deciduous by full anthesis, ovate-apiculate or short-acuminate, 2-3.5 mm long, flat to shallowly navicular but not embracing calyx, papery, inconspicuously glandular, pilosulous to densely tomentulose dorsally, thinly to densely pilosulous within; calyx 4.2-5.5 mm long, pilosulous (often densely) with fine spreading spiral hairs up to 0.5-0.8 mm long, the tube 2.2-2.6 mm long, its orifice slightly oblique but deeply recessed behind banner, the slender, castaneous ribs becoming prominent, the membranous intervals charged with 1 row of 3-4 small transparent or golden glands, the triangular-acuminate, livid, gland-spurred and -tipped teeth a little unequal, the dorsal one 2-2.9 mm long (0.3 mm shorter to 0.4 mm longer than tube), the rest a little shorter and broader; petals bicolored, the banner opening yellowish (sometimes pink-edged), rubescent in age, the epistemonous ones rose-purple, perched 0.9-1.7 mm above hypanthium rim, all (or all but wings) charged with a small subapical gland; banner 6.5-7.5 mm long, the claw 3-3.6 mm, the suborbicular, emarginate blade scarcely cordate at base, recessed at claw into a shallow cornet, 3.3-4.5 mm long, 4.4-5 mm wide; wings 6.3-7.3 mm long, the claw 2.1-2.5 mm, the oblong-elliptic blade 4.4-5.4 mm long, 2.1-2.8 mm wide; keel 8.5-9.6 mm long, the claws 3.2-3.7 mm, the obliquely ovate- elliptic blades 5.1-6.6 mm long, 3.1-4.1 mm wide; androecium 8-9 mm long, the filaments free for 2.6-3 mm, the connective gland-tipped, the anthers 0.55-0.7 mm long; pod not seen. — Collections: 2 (i).

    Rocky ledges and open brushy slopes in the oak-belt, on andesitic bedrock, ± 1830- 2400 m (6100-8000 ft), known only from Sierra Madre Occidental in extreme n. Oaxaca and adjoining Puebla. —Material: Puebla: Coxcatlan, mountains, 7-8000 ft, sept. 1909, Purpus 4147 (F, UC). Oaxaca: cf. typus.

    Dalea piptostegia (with deciduous bracts) Barneby, sp. nov., D. dorycnioidem certe affinem adspectu simulans sed bracteis ovatis (nec flabellatis) ab alabastro deciduis, spic- isque florum minus densis oblongis nec capitato-globosis abstans. — Fruticulus ramosissi- mus ad 7 dm usque altus subaequilatus nunc undique molliter tomentulosus griseus, nunc glabrescens (foliis tunc viridibus); foliola plerumque 3-7-juga oblongo-obovata emarginata 4-8 mm longa; spicae axis 2-3 (4) cm longus, dense multiflorus, floribus con- tiguis; bracteae interflorales ovatae subacuminatae 2-3.5 mm longae, utrinque pubescen- tes; calycis pilosuli tubus post vexillum recessus 2.2-2.6 mm longus, dentes inter se sub- aequilongi triangulari-acuminati ± 2-2.9 mm longi; vexillum luteolum nunc roseo-mar- ginatum mox rubescens, lamina suborbiculari ± 4.5-5 mm lata; petala epistemonea ± 1-1.7 supra hypanthium inserta, carinae ut alarum laminis roseo-purpureis ejus ± 5-6 5 mm longis. — Oaxaca: sunny open slopes and rock-ledges in the oak-belt, on ande- site, 6100 ft (± 1830 m), mountains e. of Teotitlan del Camino on road to Huautla de Jim6nez, near crest of Sierra Madre, nov 18, 1966, Ripley & Barneby 14,726. - Holotypus, NY; isotypi, CAS, F, GH, US.

    The type-population of D. piptostegia was mistaken in the field for some form of D. dorycnioides, although the spikes were altogether too long and lax to be typical and the habitat was out of harmony with what is known of the ecology of the latter species. Subsequent study revealed further differences in the spikes. That of D. dorycnioides is always conelike, usually squatly capitate, and the firmly papery, obovate-flabellate interfloral bracts persist under the calyces until they fall away with the ripe pod and seed. Bracts of the softer, oblong spike in D. piptostegia are on the contrary thrown off before the flower expands; they are, moreover, more narrowly ovate in outline and of thinner texture.

    With the typus of D. piptostegia, a densely gray-pubescent plant, the leaflets clad on both sides with a silky-tomentulose, almost plushlike vesture, I here associate a habitally similar but green dalea collected in the same range of mountains, about 30 km further north across the state line in Puebla. These specimens (Purpus 4147) are at first sight very different, for the vesture is reduced to a remnant, although the hairs are individually of the same fine spiral type. Since several other Versicolores and Tuberculatae are known to exist in more and less densely pubescent aspects, the variation is not unlikely in the context of the group.