Dalea bartoni
Rupert C. Barneby
37. Dalea bartoni Barneby
(Plate LIV)
Dwarf, tufted perennial herbs from stout woody roots and a greatly enlarged, knotty caudex up to 3 cm diam, glabrous to the ciliolate orifice of the calyx, the many slender, striate dotted but not tuberculate, simple or occasionally weakly spurred stems 1.2-2.5 dm long, by anthesis leafless at base, but thence equably leafy up to the usually solitary (rarely 2-3) terminal headlike spikes, the foliage pallid or yellowish green, the thick-textured leaflets smooth above, multipunctate beneath; leaf-spurs 0-0.4 mm long; stipules triangular-subulate 0.2-1.2 mm long, early becoming brown and deciduous; intrapetiolular glands small, immersed; post-petiolular glands small or 0; leaves petioled, the primary cauline ones 8- 20 ( 23) mm long, with narrowly green-margined, ventrally grooved rachis and 5-9 oblanceolate to obovate-cuneate, emarginate, folded and backwardly arched leaflets 2.5-7.5 mm long, the terminal leaflet either sessile or minutely stalked, the uppermost leaves like those of some axillary branchlets often smaller and 3-foliolate; peduncles 1-6 mm long; spikes shortly 5-30-flowered, subglobose to shortly oblong, without petals ± 8 mm diam, the calyces spreading-ascending, the axis becoming 3-14 mm long; bracts dimorphic, the lowest persistent, ovate, ± 2 mm long, the (little known) interfloral ones early deciduous, papery-castaneous except for narrow membranous margins near base, up to 3 mm long; spicular bracteoles 0.2-0.5 mm long; calyx obliquely obovoid-pyriform, 3.8-4.3 mm long, glabrous externally, at base broadly obconic, gray-glaucescent, and (dry) ± pleated, thence castaneous and charged between the slender, immersed ribs with prominent yellow glands, these ± 1-seriate in the narrower panels, numerous and scattered in the broad adaxial ones, the tube 2.8-3.5 mm long, strongly oblique at orifice, the sinus behind banner shallowly recessed but much broader than the rest, the 3 abaxial teeth narrowly triangular-subulate, 0.7-1 mm long, the ventral pair shorter, broadly deltate, all densely ciliolate and internally pilosulous with silvery hairs up to ± 0.2 mm long; petals white, glandless, the epistemonous ones perched at separation of the filaments; banner ± 5.4 mm long, the filiform claw 3 mm, the deltate-obcordate, distally hooded blade 2.5 mm long, 3 mm wide; epistemonous petals all similar (the abaxial pair slightly larger), ± 3.7 mm long, the obovate blades ± 3 mm long, 1.5 mm wide, cuneately narrowed at base into a claw less than 1 mm long; androecium 9.5 mm long, the column 4 mm, the free filaments up to 4.5 mm long (anthers not seen); pod half-obovoid, ±2.8 mm long, the ventral suture nearly straight, the dorsal one strongly convex and slenderly keeled along the prow, the valves membranous but heavily castaneous-flecked in lower thence firm, thinly and minutely appressed-pilosulous along the abaxial curve, densely short-barbate at apex and along base of style; seed nearly 2 mm long. — Collection: 1 (typus).
On limestone at ± 1080 m (3900 ft), reportedly rare, known only from the type- locality in Brewster County, trans-Pecos Texas.— Flowering in July.
Dalea bartoni (Barton Holland Warnock, 1911- , creator of the SRSC herbarium) Barneby, sp. nov., D. sabinali Wats, necnon D. scariosae Wats, arete affinis sed huic propior, ab ilia foliolis paucis 2-4-jugis obcuneatis parvis 2.5-7.5 mm (nec 5-8-jugis lineari-oblanceolatis 8-15 mm) longis, caulibus nanis vix 2.5 (nec 2-6) dm longis, stipulis par- vulis, ab hac caulibus nanis simplicibus monocephalis (nec 2-7 dm longis diffuse multi- ramosis polycephalis), ab ambabus spica pauciflora capitata subsessili petalisque albis absimilis. — Texas. Brewster: limestone soil on C. F. Cox Ranch, alt. 3600 ft, fr. with a few late flowers, Jul 31, 1953, Barton H. Warnock 11,398. — Holotypus (2 sheets), SRSC; isotypi, IA (fragm), NY, TEX.
The type collection of D. bartoni as represented at TEX was identified by Wemple as Petalostemon sabinale, and is apparently the basis of the Brewster County record for that species mentioned in his revision (1970, p. 54) but omitted from the map (1970, p. 39). While the calyces of these two prairie-clovers are undeniably similar and their kinship not in question, D. bartoni differs in so many characters of stature, foliage, length of spike, and petal-color, that I cannot accomodate it in the same species as D. sabinalis. The really close relationship of D. bartoni is believed to lie rather in the direction of D. scariosa, a species hitherto considered greatly isolated, both taxonomically and geographically, in fact referred by Wemple to a monotypic series in Petalostemon. The calyces, however, of D. scariosa, D. bartoni, and D. sabinalis are essentially identical, and the three entities form a little group within sect. Kuhnistera ser. Candidae which could be treated in either of two ways: as a polymorphic single species comprising three geographically disjunct races, or as a set of three autonomous species, obviously related but separated by a substantial set of morphological discontinuities. The differences are of the same order as exist between, for example, D. feayi and D. carnea, or D. Candida and D. multiflora, differences that is of foliage, habit, and size or arrangement of the spikes, but involving no obvious structural modification of the flower. In the context of sect. Kuhnistera, D. bartoni emerges as a well differentiated species.
The unique features of D. bartoni are the short, slender, almost always monocephalous stems less than 2.5 dm long, the reduction of the spike to a subsessile, capitate or shortly oblong head of 5-30 flowers, and the white (not pink or lilac) petals. The foliage and short stipules resemble those of D. scariosa closely, but the stems of the latter are characteristically longer and freely branched, forming cartwheels of foliage 5-15 dm in diameter, each branchlet going out into loose, many-flowered, ament-like rather than headlike spike of lively pink flowers. The known range of D. scariosa lies at ± 1500 m along a 50 km stretch of the Rio Grande valley in north-central New Mexico, its nearest point 550 km distant from D. bartoni. The differential characters of D. sabinalis are the longer stems (2.5-6 dm), longer stipules (2-3.5 mm), 5-8 pairs of linear leaflets up to 7-15 (not 2.5-7.5) mm long, and an elongate, many-flowered spike of pink flowers becoming 4-9 cm long and elevated beyond the uppermost cauline leaves on a naked peduncle about 5-12 cm long. The known range of D. sabinalis extends around the south edge of Edwards Plateau at elevations near and below 500 m, its most western station being in the drainage of Devils River about 200 km east of D. bartoni.
Professor Warnock, who kindly loaned the material in his herbarium, tells me that the type-locality is on limestone in the pinyon belt and situated about 20 miles west of Sanderson, probably in the drainage of San Francisco Creek, near the common boundary point of Terrell, Brewster, and Pecos Counties. It is a pleasure to associate this charming dalea with the name of the collector, who has done so much to make known the rich endemic flora of trans-Pecos Texas. There is already a Dalea warnockii, but synonymous with D. wrightii Gray.
References: [Article] Barneby, Rupert C. 1977. Daleae Imagines, an illustrated revision of Errazurizia Philippi, Psorothamnus Rydberg, Marine Liebmann, and Dalea Lucanus emen. Barneby, including all species of Leguminosae tribe Amorpheae Borissova ever referred to Dalea. Mem. New York Bot. Gard. 27: 1-892.Multimedia:
