Dalea rubrolutea
Rupert C. Barneby
16. Dalea rubrolutea Barneby
(Plate XL)
Herbaceous or weakly suffrutescent perennial, the apparently diffuse stems up to 6dm long, simple and glabrous in the lower thence paniculately branching, chestnut-purple, thinly and minutely pilosulous with curly and incurved hairs up to 0.2 mm long, verruculose throughout with prominently convex and grainlike warts, the foliage green, the lower leaves glabrate, the upper ones minutely pilosulous, the leaflets of rather thick texture, gland-dotted beneath; leaf-spurs 1-2 mm long; intrapetiolular glands small, hemispherical; post-petiolular glands conspicuous, mammiform; main cauline leaves 1.5-4 cm long, with narrowly margined, narrowly grooved rachis and 7-11 pairs of oblong, oblong-oblanceolate, or narrowly obovate, emarginate, bluntly gland-mucronulate leaflets 2.5-6.5 mm long, the uppermost leaves smaller but the smaller leaflets no less numerous; peduncles at first leaf-opposed then terminal to all the branchlets, 1-4.5 cm long; spikes densely many-flowered, ovoid becoming oblong, without petals 8-9 mm diam, the densely pilosulous axis 1-2.6 cm long, concealed by crowded calyces; bracts persistent, 2-3 mm long, subhomomorphic but the lowest shorter, all obovate, boat-shaped, emarginate with a very short puberulent tail (± 0.5 mm) in the sinus, the submembranous body glabrous or distally puberulent, lurid and orange-glandular dorsally, pallid-margined; calyx 3.8-4.2 mm long, glabrous except for the slightly constricted, scarcely oblique orifice, the subtumid tube 3.2-3.8 mm long, 1.7-2 mm diam, lustrously hyaline, orange-tinged, the slender ribs not prominent, livid-castaneous, the broad intervals charged with 1-3 large elliptic, orange blister- glands arranged in a single rank, the teeth unequal, the dorsal one shortest and narrowest, the ventral and lateral pairs broadly obovate-truncate, wider than long, ± 0.4 mm long, all charged around the apex with 3(4) livid gland-spurs, ciliolate around the livid margins; petals (dry) pale yellow, all tipped with a small gland, the banner charged with a few tiny glands near the eye of the blade, the inner ones elevated 2-2.5 mm above the hypanthium rim (perched just below separation of the filaments), the keel petals free even in bud; banner 3.8-4.6 mm long, the slender claw 1.7-2.4 mm, the ovate, emarginate, nearly erect blade open at base, 2.3-2.6 mm long, 2 mm wide; wing- and keel-petals almost alike, the latter a trifle broader and more oblique at base of blade, 2.4-3 mm long, the claw 0.5-0.7 mm, the broadly oblanceolate to obovate-oblong blades cuneate at base, 1.9-2.3 mm long, 0.6-1.3 mm wide; androecium 10-merous, 3.8-5.5 mm long, the longest filament free for 1.8-2.8 mm, the gland-tipped anthers ± 0.45 mm long; ovary subglabrous, the terminal style bearing a few hairs at base, the pod unknown.— Collections: 2(o).
Habitat not recorded, supposedly found at "6500-7500 ft" (± 1950-2150 m) but from the xerophytic appearance of the plant to be sought in cactus-thorn-forest considerably lower, known only from the valley of Rio Tomellin in distr. Cuicatlan, on the Atlantic slope in n.-e. Oaxaca. — Flowering November-December. — Material: "Mexico", without exact locality, Karwinski 5764-5 (M). Oaxaca: cf. typus.
Dalea rubrolutea (red and yellow) Barneby, nom. nov., based on Thombera lutea (yellow) Rydb., N. Amer. Fl. 24: 117. 1920. — "Type collected on the west side of the valley of Cuicatlan, Oaxaca, November 10, 1894, E. W. Nelson 1896..." — Holotypus, US! isotypus, NY! — Non Dalea lutea (Cav.) Willd., 1803. Parosela rubricaulis (red-stemmed) Rose ex Rydb., N. Amer. Fl. 24: 119. 1920, in syn., hyponym. Non P. rubricaulis Rusby, 1910, nec Dalea rubricaulis Ulbr., 1915.
Although first collected by Baron von Karwinski as long ago as 1827, D. rubrolutea has been encountered only once since; nothing is known of its habitat, and the specimens, as often happens in Dalea, do not convey a clear picture of the plant’s habit of growth. Plate XL couples D. rubrolutea with the humifuse D. viridiflora, superficially similar in its yellowish, gland-tipped petals issuing from a lustrously hyaline, incipiently inflated calyx, suggesting that the stems of both are prostrate; it seems as likely, however, that the relatively stiff and coarse stems of D. rubrolutea are virgately assurgent or erect. More collections of this isolated and peculiar monotype are needed.
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:
