Dalea greggii
Rupert C. Barneby
104. Dalea greggii Gray
(Plate XCVI)
Slender subshrubs, colonial by means of arching, tip-rooting stems, forming sub- prostrate mats or low thickets rising to 3 (5) dm from ground-level, the old stems castaneous or blackish, often glabrate, the young, smooth or sparsely low-verruculose stems and the foliage densely silky-pilosulous with subappressed, loosely ascending, or (especially the stems) spreading and shaggy hairs up to 0.35-0.75 mm long, the leaves silvery or silvery-villous (sometimes tarnishing in herbarium), the primary cauline ones subtending short-shoots or fascicles of smaller ones; leaf-spurs 0.4-1 mm long; stipules subulate, lanceolate, or linear, chartaceous, livid or castaneous, 1-2.5 (3) mm long, pubescent dorsally, glabrous or glabrate within; intrapetiolular glands 2, setiform; post-petiolular glands small, often concealed by vesture; leaves shortly petioled or subsessile, the primary cauline ones 0.6-2.5 (3) cm long, with narrowly thick-margined rachis and 2-4 pairs of broadly to narrowly obovate to broadly oblanceolate, commonly emarginate, sometimes gland-mucronate or abruptly short- acuminate, flat or loosely folded leaflets 2-7 (9) mm long, the terminal one sessile, the leaves of axillary spurs similar but in all parts smaller; peduncles 0-4 (6) cm long, those terminal to primary axes mostly pedunculate, those terminal to branchlets mostly sessile or nearly so; spikes dense but not conelike, subglobose to ovoid becoming ovoid to shortly oblong-cylindroid, without petals 8-11 mm diam, the pilosulous axis finally 0.4-3, exceptionally up to 5.5 cm long; bracts persistent through anthesis, deciduous with the ripe fruit, ovate to lance-acuminate or linear-elliptic, 2-4 mm long, the broader ones ± navicular at base, the rest flat or nearly so, all subherbaceous becoming stiffly papery, glandular but the glands often concealed dorsally by the dense pubescence of subappressed or spreading, silky hairs, the inner face silky-strigulose; calyx (4) 4.2-6 mm long, densely silky-pilosulous with spreading hairs, the tube (2) 2.2-2.8 (3) mm long, the slender ribs becoming prominent, the thin but not hyaline intervals charged with 3-8 (10), when few 1-seriate, when many scattered, minute transparent or larger golden glands, the deltate-acuminate to lanceolate or subaris- tate, herbaceous finally brown or livid, gland-spurred teeth a little unequal, the dorsal one longest, 1.7-3 (3.2) mm long (0.4 mm longer to 1.3 mm shorter than tube), the ventral pair somewhat broader and shorter; petals bicolored, gland-tipped or not, the banner opening cream or pale yellow, early rubescent, sometimes gland-sprinkled, the epistemonous ones pink or pink-purple, often with pale outer edges, perched much below middle of androecium, 1.4-2.2 mm above hypanthium; banner 4.4-6.2 mm long, the claw (1.8) 2.3-3.3 mm, the deltate-cordate obtuse or emarginate hooded blade recurved through ± 40°, 2.6-3.5 mm long, 3.2-4.3 mm wide, recessed at base into a shallow cornet; wings 4.4-6.6 mm long, the claw 1.1-2.4 mm, the oblong-elliptic blade 3.2-4.6 mm long, 1.6-2.4 mm wide; keel 5.5-7.2 mm long, the claws 1.8-3 (3.6) mm, the broadly oval-obovate blades 4-4.8 (5.3) mm long, 2.2—3.3 mm wide; androecium 10-merous, 5.5-7.5 mm long, the longer filaments free for 1.7-2.4 mm, the connective gland-tipped, the anthers 0.5-0.7 mm long; pod in profile obliquely obovate or semi-obovate, 2.1-2.8 mm long, the ventral suture slightly concave or slightly convex, the valves hyaline at base, papery distally, pilosulous from middle upward and sparsely gland-sprinkled; seed 1.6-2.2 mm long; 2n = 7 II (Mosquin).— Collections: 77 (xv).
Stony hills and plains, in open situations but entering diverse plant communities, from coastal savanna in Tamaulipas through deserts of the interior up to the arid grasslands of the Central Plateau, near sea-level in Tamaulipas and reaching 2250 m (7500 ft) in Zacatecas, strongly but not obligately calciphile, common on both slopes of Sierra Madre Oriental from s.-e. San Luis Potosi n.-w. through all the limestone ranges of Coahuila into trans-Pecos Texas (Val Verde, Brewster, Pecos cos.) and just into n.-e. Chihuahua (Sa. de los Pinos, mpo Guadalupe), w. over the Meseta to the headwaters of Rio Nazas in n.-centr. Zacatecas, the n.-e. third of Durango, and just into s.-centr. Chihuahua (mpo Hidalgo del Parral); from San Luis Potosi extending s. in scattered localities at middle elevations along the s.-e. margin of the Meseta, apparently always on sedimentary formations, through n. Hidalgo (mpos Jacala, Metz- titlan) and (?isolated) Queretaro (mpo Tequisquiapan) to s.-e. Puebla (near Puebla, and locally plentiful in the Tehuacan desert) into the highlands of n. Oaxaca (mpos Huajuapan de Leon, Teposcolula, Asuncion Nochixtlan), there passing into D. leucosericea. — Flowering February to May, July to December, perhaps intermittently whenever conditions permit. —Representative: UNITED STATES. Texas: Warnock 468 (TEX), 11,346 (WIS), 21,254 (TEX); McVaugh 10,682 (ENCB, TEX); Correll & Hanson 29,884 (RENNER). MEXICO. Chihuahua: LeSueur 1510 (ARIZ, F, TEX); Ripley & Barneby 13,910 (NY). Coahuila: Johnston 8421 (GH, TEX), 8553, 8954 (GH); Palmer 37 (F, NY, UC); Purpus 4736 (F, UC). Nuevo Leon: Wamock & Barkley 14,815M (F, NY, WIS); Barkley 16,034M (GH, NY, TEX, US); Ripley & Barneby 13,253 (CAS, NY). Tamaulipas: Graham & Johnston 4383A (TEX); Stanford, Retherford & Northcraft 941 (ARIZ, NY); Ripley & Barneby 14,753 (CAS, MEXU, NY, US). Durango: Gentry 6897 (NY); Ripley & Barneby 13,950 (NY). Zacatecas: Gentry 8554 (UC); Ripley & Barneby 13,474 (CAS, NY). San Luis Potosi: Rzedowski 9567, 9627, 24,686 (ENCB); Ripley & Barneby 13,304 (CAS, NY, MEXU, US), 14,773 (CAS, MICH, MEXU, NY, US). Queretaro: Hernandez 52 (ENCB). Hidalgo: Troll 427 (M); J. Vasquez and M. E. Moncayo in 1965 (ENCB). Puebla: Arsene 1997 (NY); Purpus 2649 (F, UC); Rose & Hough 10,160 (NY, US). Oaxaca: Mosquin et al. 6677 (NY); Matuda 37,504 (MEXU); Ripley & Barneby 13,642, 13,656, 14,584 (NY).
Dalea greggii (Josiah Gregg, 1806-1850) Gray, Mem. Amer. Acad. II, 5 (Pl. Thurb.): 314. 1854 ("Greggii"). — "(Dry.hills, near Buena Vista, Coahuila, Dr. Gregg) Cerro Gordo, Coahuila; November; 1852." — Lectotypus (Gentry, 1950, p. 230), labelled "Near Buena- vista, March 27/47, Gregg", GH! isotypus, NY! paratypi (Thurber from Cerro Gordo), GH. NY! — Parosela greggii (Gray) A. Heller, Catal. N. Amer. Pl. ed. 2, 6. 1900.
Parosela fulvosericea (brownish-silky, the hairs tarnishing when dried) Rydb., N. Amer. Fl. 24: 89. 1920.— "Type collected in the region of San Luis Potosi, 1878, Parry & Palmer 148, in part..." —Holotypus, US # 24432 in part (mixed with D. dorycnioides), US!- Dalea fulvosericea (Rydb.) Gentry, Madrono 10: 249. 1950.
A species of wide range and great altitudinal tolerance, consisting of several races that seem at present out of reach of taxonomic definition. Following Gentry (1950, p. 230, Pl. 15, fig. 1, map), I visualize D. greggii more easily in terms of the growing plant than of technical characters, each of those that at first seemed useful having proved fallible in practice. At the time of Gentry’s revision D. greggii was best known from the high grasslands around the east and southwest periphery of the Chihuahuan Desert, but subsequent collecting has shown it to be equally common along the east piedmont of Sierra Madre Oriental, whence it strays off onto the coastal plain in Tamaulipas; and it is now known to follow the limestones of the Sierra Madre south as far as the highlands of northern Oaxaca. I am in full agreement with Gentry’s segregation of the neatly allopatric and morphologically distinct D. pulchra, included by earlier workers in D. greggii, but I cannot now exclude from the latter the plant described as D. fulvosericea, discussed in more detail below.
On bare gravelly plains or hilltops and eroding bluffs in the northern and western segments of its range, at elevations above 1000 m, the average plant of D. greggii forms a mat of wiry, procumbently arching and interlacing stems that take root wherever they touch the ground, thereby forming masses up to 1-2 m diameter but only 1-2 dm high. The stem-pubescence associated with this growth-form is subappressed or ascending, the leaves are small and silvery, and the heads are mostly short, ovoid or conic, but the first of each major cauline axis nevertheless sometimes oblong (axis up to ± 2 cm; cf. Correll & Johnston 19354 from trans-Pecos Texas, RENNER). Even on the plateau, however, plants seeding into protected gullies become taller, with high-arching stems less prone to root, and ampler cauline leaves. This tendency to luxuriance becomes exaggerated under moister, warmer conditions encountered along the east piedmont of Sierra Madre, where the stems are still potentially tip-rooting but form thickets up to 3-5 dm tall and the spikes become more often oblong (axis up to 5.5 cm; cf. Runyon 889 from Tamaulipas); and the same region yields occasional glabrescent populations with greenish foliage and only thinly pubescent calyces (Graham & M. Johnston 4666A, MEXU, TEX). With added stature, but inconsistently, the pubescence of stem and leaf, or of stem only, while no thinner becomes looser and less glossy. In southeast San Luis Potosi and adjoining Hidalgo and Queretaro this type of vesture, accompanying spikes either short or long for the species, becomes shaggy-villous, and the stems are perhaps (herbarium specimens are enigmatic in this context) largely ascending, not radicant. The typus of Parosela fulvosericea, placed by Rydberg (1920) not near P. greggii but among his Tuberculatae, represents this more loosely villosulous and more fruticose phase, which appears, nevertheless, to be connected with typical D. greggii by intermediate forms.
No populations of D. greggii are known from between northern Hidalgo and southern Puebla; but the species becomes again common in the Tehuacan desert, here assuming a form as prostrate and readily rooting as that of the Meseta Central, and continues south into arid mountains of northern Oaxaca, where it passes imperceptibly into D. leucosericea.
A remarkable plant, diffidently interpreted (ad interim) as a coarsely leafy form of D. greggii, has been collected out on the Gulf coast of Tamaulipas, close to sea-level (Alta- mira road, Tampico, Kenoyer 801a, F). The material examined, not of first quality, suggests a distinct entity, notable for its large bracts (to 7 mm), large calyx (tube 3-3.2 mm, teeth 2.9-3.2 mm) with many (6-10) small scattered glands in each intercostal panel of the tube.
While D. greggii is believed to be closely allied, through D. sericea, to typical members of ser. Psoraleoides, its stems are sometimes moderately warty, and it is then with difficulty excluded from ser. Tuberculatae, among which, as we have seen, Rydberg aligned one form. It is more readily excluded from ser. Versicolores, where Rydberg placed the typical phase, by a combination of few, normally silky leaflets and internally pubescent bracts. With the aim of covering all eventualities, I have endeavored to key D. greggii into all three series.
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:
