ASCLEPIA DA CEA E. 745 



23 Asclepias pumila (A. Gray) Vail. Low Milkweed. (I. F. f. 2921.) 

 Stems 4-25 era. high, tufted from a woody root. Leaves numerous, crowded, 

 sometimes obscurely whorled, filiform-linear, 2.5-5 cm - lo »g< smooth or minutely 

 roughened, the margins revolute; umbels 2-several, short-peduncled, few-flowered; 

 pedTcels filiform, puberulent, 6-9 mm. long; corolla greenish white, its segments 

 oblong, 3-4 mm. long; hoods white, erect, oblong, entire, equalling the anthers, 

 shorter than the slender incurved horn; follicles erect on erect fruiting pedicels, 

 narrowly spindle-shaped, 3-5 cm. long, finely puberulent. Dry plains, S. Dak. to 

 Ark., Colo, and N. Mex. July- Aug. 



2. ASCLEPIODORA A. Gray. 

 Perennial herbs, similar to Asclepias, with entire leaves, and rather large 

 flowers in terminal umbels. Sepals lanceolate. Corolla rotate, its segments spread- 

 in^. Hoods oblong, inserted over the whole of the short corona-column, curved 

 upward, obtuse, crested within, at least in the upper part, slightly longer than 

 the anthers ; at the sinuses between the hoods a small lobe or appendage, alternate 

 with the anther-wings, simulating an inner crown. Anthers tipped with a scarious 

 membrane, their wings horny, narrowed below, sometimes angled above the 

 middle. Pollen-masses pendulous, pyriform, longer than their caudicles. Follicles 

 ovoid or oblong, acuminate, with or without soft spinose processes, erect or ascend- 

 ing on the decurved or twice bent fruiting pedicels. [Greek, gift of iEsculapius.] 

 Five or six species, natives of the southern U. S. and Mex. 



Glabrous or nearly so; leaves oblong to ovate-lanceolate; umbels usually more than one, 



corymbose. x - A > viridis. 



Stem rough-puberulent ; leaves lanceolate; or linear, acuminate ; umbels solitary. 



2. A. decurnbens. 



1. Asclepiodora viridis (Walt.) A. Gr. Oblong-leaved Milkweed. 

 (I. F. f. 2922.) Stem erect, rather stout, simple, 3-6 dm. high. Leaves rather 

 thin, short-petioled, 6-13 mm. long; pedicels slender; corolla globose-ovoid in the 

 bud, greenish, its segments, when expanded, oblong, obtuse or acute, 9-13 mm. 

 long. 2-3 times as long as the purplish or violet entire-margined hoods ; anther- 

 wings narrow, scarcely angled above ; fruiting pedicels twice bent ; follicles 

 ascending, puberulent, 5-8 cm. long, sometimes with soft spinose projections. In 

 dry soil, 111. to Kans., Tex., S. Car. and Fla. May-July. 



2. Asclepiodora decurnbens (Nutt.) A. Gray. Decumbent Milkweed. 

 (I. F. f. 2923.) Stems decumbent or ascending, rather stout, 2-5 dm. long. Leaves 

 firm, glabrous above, puberulent, at least on the veins beneath, narrowed at the 

 base. 8-18 cm. long; umbel many-flowered; pedicels rather stout; corolla depressed- 

 globose in the bud. greenish, its segments, when expanded, ovate or broadly oval, 

 somewhat longer than the hoods ; hoods purple, obtusely 3-lobed on the ventral 

 margins, about 6 mm. long, their tips incurved ; anther-wings broad, angled above; 

 follicles nearly erect on the recurved fruiting pedicels, 8-10 cm. long, puberulent, 

 at least when young, with or without soft projections. In dry soil, Kans. to Tex., 

 Mex., Utah and N. Mex. April-June. 



3. ACERATES Ell. 



Perennial herbs, similar to Asclepias, with thick leaves, and green or purplish 

 flowers in short-peduncled or sessile umbels. Calyx 5-parted or 5-divided, the 

 segments acute, glandular within. Corolla deeply 5-cleft, the segments valvate, 

 reflexed in anthesis. Corona-column very short. Corona of 5 involute-concave or 

 somewhat pitcher-shaped hoods, neither horned nor crested within or in one spe- 

 cies having a small interior crest and usually a few small processes at the base of 

 the anther-wings, forming an obscure inner crown. Pollen-masses solitary in each 

 sac, oblong, pendulous. Stigma 5-lobed. [Greek, without horn, referring to the 

 crown.] About 7 species, natives of N. Am. 

 Umbels sessile, or very nearly so, mostly axillary. 



Leaves oval to linear; hoods entire at the apex. 1. A. viridiflora. 



Leaves narrowly linear; hoods 3-toothed. 2. A. angusti/olia. 



Umbels, at least the lower, distinctly peduncled. 



Plants glabrous, or nearly so; umbels usually several; leaves narrow. 



