152.  Dalea aurea Nuttall

(Plate CXXXVII)

Perennial herbs with (1) 3-9 (15) stiffly erect or virgately ascending stems from a short caudex, (2) 3-7.5 dm tall, silky-pilose or -pilosulous almost throughout with subappressed, ascending, and often a few spreading hairs up to (0.5) 0.7-1.3 (1.5) mm long, the stems simple and monocephalous or, less often, branched distally, with 1 or few small lateral spikes elevated beyond the terminal one, the leaflets ± bicolored, densely pubescent and punctate beneath, above more thinly pubescent and deeper (when dried sometimes verdigris) green, more rarely medially glabrescent or truly glabrous, the vesture silvery-gray when fresh, early tarnishing when dried; leaf- spurs 0.7-1.5 mm long; stipules subulate to narrowly lanceolate, early becoming dry, fragile, stramineous, (0.8) 1.2-3 mm long, thinly pilosulous or glabrate; leaves 1-3.5 (4) cm long, scattered and reduced in size upward, the uppermost sometimes bracteiform, all usually deciduous as the fruit ripens, the margined and punctate petiole and rachis together 0.7-2.5 cm long, the leaflets 3-7, always 5 on some leaves, obovate to oblong-oblanceolate or oblanceolate, obtuse, obtuse and mucronulate, rarely acute, flat or loosely folded, (3) 4-16 (20) mm long, the terminal one usually raised beyond the last pair; spikes very shortly peduncled or sessile (but sometimes appearing long- pedunculate due to reduction of upper leaves), densely many-flowered, conelike, ovoid becoming oblong-cylindroid, without petals (12) 14-21 mm diam, the densely pilosulous axis (1) 1.5-6 cm long; bracts deciduous only with the calyces, subdimor- phic, the lowest ovate-cuneate, firm, 2.5-5.5 mm long, the inner ones lance-elliptic acuminate, becoming papery, all densely silky-pilose dorsally and ciliate except for the slender livid tip, the lowest always, often all, finely punctate; calyx 6.1-7.4 mm long, densely silky-pilose with spreading-ascending hairs up to 1-2.2 mm long, the turbinate tube 2.2-2.8 mm long, the stramineous ribs becoming prominent, cordlike, the membranous intervals charged with 1 row of 3-4 small transparent glands, the narrowly lance-acuminate teeth 3.5-5 mm long, plumose but aristiform, at tip livid and glabrescent, at anthesis ± connivent, in fruit stellately divergent; petals pale, clear yellow, unchanged in drying, the banner-blade sometimes charged with a crescent of glands, the rest glandless, the epistemonous ones perched near middle of androecium, the keel 4.8-7.3 mm above hypanthium; banner 6.3-8.6 mm long, the claw 3.5-5 mm, the deltate-cordate obtuse or subacute, hooded blade 3-4.2 mm long, 3.2-4.4 mm wide, recessed at the claw into a comet; wings 5.2-6 mm long, the claw ± 1 mm, the obliquely ovate or oblong blade 4.7-5.6 mm long, 2-2.4 mm wide; keel 5.7-8.5 mm long, the claws 1.4-2.1 mm, the broadly oblong-elliptic blades (4.7) 5-7 mm long, 2.6 -3.2 mm wide; androecium 10-merous, 10-12.5 mm long, the longer filaments free for 2.5-3 mm, the pallid anthers 0.65-0.9 (0.95) mm long; pod (of the section) 3-3.5 mm long; seed castaneous or mahogany-brown, smooth and lustrous, 2-2.4 mm long; n = 7 II, 2n 14 (Mosquin). — Collections: 151 (iv).

Prairies and dry hillsides, on a variety of soils but perhaps most vigorous on sedimentary bedrock, especially limestone, 10-1800 (1950) m (30-6500 ft), widely dispersed and common over the greater part of Texas w.-ward from the post-oak savanna belt, s. into the Gulf Coastal Prairie, n., still common, through Oklahoma and the western two thirds of Kansas (e. to Cowley and Republic counties) into (becoming rare and scattered) w. Nebraska and s.-w. South Dakota, and w., nowhere abundant, into Colorado e. of the Rocky Mountain foothills (up the Arkansas into e. Fremont County), and the Pecos valley in New Mexico; disjunct in e.-centr. Arizona (extreme s. Navajo County); from Texas extending s. into the mountains of Coahuila (Sierras Encantada, del Carmen, de la Madera, de la Gloria, de Monclova) and adjoining Chihuahua (Sierra de Encinillas).—Flowering (June) July to September. —Representative: UNITED STATES. South Dakota: Rydberg 608 (NY). Nebraska: Clements 2708 (NY); Tolstead411054 (UC). Colorado: Clokey 4195 (UC); W. A. Weber 4401 (UC). Kansas: C. H. Thompson 27 (NY, UC); Rydberg & Imler 489 (NY); McGregor & Jackson 102 (NY). Oklahoma: E. J. Palmer 12,595 (NY, UC); Waterfall 15,964 (OKLA, UC); G. W. Stevens 1048 (NY, OKLA). Texas: Lindheimer 754 (NY, UC); A. Heller 1856 (L, NY, OKLA, UC); T. & L. Mosquin 5703 (NY); Moore & Steyermark 3613 (NY, UC); Ripley & Barneby 14,785 (DAO, NY). New Mexico: Degener 5031 (NY); Br. Anect 162 (NY). Arizona: Palmer 611 (NY, UC, US). MEXICO. Chihuahua: Stewart 757 (GH, TEX). Coahuila: Wynd & Mueller 464 (ARIZ, GH, NY); Marsh 690 (F, GH, OKLA, TEX), 2145 (OKLA, GH); Palmer 226 (NY, US).

Dalea aurea (golden, of the petals) Nutt, ex Pursh, Fl. Amer. Sept. 740. 1814. — "In Upper Louisiana. Bradbury...v. s. in Herb. Bradbury.", fide Nuttall, Gen. 2: 101. 1818, "near White River, Missouri [= s. South Dakota]" —Holotypus not seen; isotypus, labelled "Dalea aurea, Bradbury, herb. Lambert.", NY (herb. Torr., fragm.)! —Psoralea aurea (Nutt.) Poir. in Lamk., Encycl. Suppl. 4: 590. 1816. Parosela aurea (Nutt.) Britt., Mem. Torrey Club 5: 196. 1894.

Cylipogon capitatum (with flowers in heads) Raf., "Jour. Phys. 89: 97. 1819"; cf. supra sub sect. Cylipogon. — No typus known; the description probably based on accounts of Pursh and Nuttall. — Petalostemon capitatum (Raf.) DC., Prod. 2: 244 (with note of interrogation). 1825.

The Golden Prairie-clover, a common ornamental wild-flower of the southern Prairie States, is distinguished from other yellow-flowered daleas by its tall wandlike stems ending in one, or sometimes one large and a few smaller dense, conelike heads of silvery-pilose calyces. A rare tall form of D. nana sometimes approaches it in stature, but has much smaller petals that, unlike those of D. aurea, turn pinkish-brown when dried. The rare D. boraginea, found within the range of D. aurea in Coahuila, is similar in habit, but has all leaves 3-foliolate (not mostly 5-foliolate) and a characteristic hispid pubescence.

The species varies little in gross appearance or in fine detail. The leaflets may be silvery-pubescent on both sides or glabrate above, and the upper surface, always darker green (below the vesture) than the lower, often but not invariably turns verdigris-green in the herbarium, a curious feature common to this and some sympatric but only distantly related members of subgen. Dalea. The climatic tolerance of D. aurea is exceptional, for it extends in Texas southward out onto the sands of the Gulf Coastal Prairie and in Colorado and New Mexico up to the Rocky Mountain piedmont. It is reported from Wyoming, but I have seen no specimen from west of the Black Hills in South Dakota.