670 ASCLEPIADACEAE 



trorse. Gynoecium of 2 carpels. Styles 2, connected at the summit by 

 the stigmas. Ovules numerous, anatropous, pendulous. Fruit of two 

 carpels. Seeds many, compressed, appendaged by a long coma. 



Crowns wanting; corolla urceolate or campanulate ; stem twining. 1. ASTEPHANUS. 

 Crowns present; corolla rotate or open-campanulate. 



Crowns double, the outer of a shallow undulate ring; plants twining. 



2. PHILIBERTELLA. 

 Crowns simple; plants erect or decumbent, not twining. 



Corolla-lobes reflexed during anthesis. 



Hoods of the crown crestless or with an obscure crest within. 



3. ACERATES. 

 Hoods of the crown with a horn-like or tooth-like crest within. 



4. ASCLEPIAS. 

 Corolla-lobes erect-spreading during anthesis. 5. ASCLEPIODORA. 



1. ASTEPHANUS R. Br. 



Perennial herbs or suffruticose plants, ours twining. Flowers perfect, regu- 

 lar, umbellate. Calyx 5-lobed, destitute of glands. Corolla urceolate or cam- 

 panulate, 5-cleft; lobes slightly convolute. Crown wanting. Stamens inserted 

 on the base of the corolla-tube. Follicles long-acuminate, smooth. 



1. A. utahensis Engelm. Perennial from a thick root; stem slender, fili- 

 form; leaves linear-filiform; umbels short-peduncled, 3-5-flowered; corolla dull 

 yellow, campanulate, 2 mm. wide; lobes ovate, somewhat hooded, papillose- 

 puberulent within. Dry sandhills: s Utah Ariz. L. Son. 



2. PHILIBERTELLA Vail. 



Twining perennial herbs, or partly shrubby. Leaves opposite, linear, cor- 

 date, or hastate. Flowers perfect, regular, umbellate. Calyx small, 5-lobed. 

 Corolla campanulate or rotate, with a double crown; outer crown in the throat 

 ring-like, undulate; lobes 5, longer than the tube. Stamina! crown represented 

 by 5 turgid fleshy or hard scales or flat appendages at the base of the subsessile 

 column. Follicles slender, naked. [Philibertia Benth. & Hook., not H.B.K.] 



Crowns separate by a short column; stem glabrous. 1. P. cynanchoides . 



Crowns contiguous; stem puberulent or pubescent. 2. P. heterophylla. 



1. P. cynanchoides (Dec.) Vail. Stem 2-12 m. high; leaves 1.5-6 cm. 

 long, deeply cordate, sagittate, or hastate, cuspidate; corolla white or cream- 

 colored, purple-tinged at the apex; outer crown shallow; scales of staminal 

 crown broadly oval, obtuse or acutish; follicles 3-7 cm. long, long-attenuate. 

 Philibertia cynachoides A. Gray. Along rivers: Tex. s Utah Ariz.; Mex. and 

 C.Am. L. Son. Je-S. 



2. P. heterophylla (Engelm.) Cockerell. Twining perennial; leaves 3-5 

 cm. long, 2-4 mm. wide, some acute, some rounded or cordate-auriculate or 

 truncate at the base; corolla yellowish, purplish, or whitish; lobes ovate, smooth; 

 follicles 6-8 cm. long, attenuate at the apex, 6-7 mm. thick, puberulent. Phili- 

 bertia linearis heterophylla A. Gray. Dry ground: Ariz. s Utah s Calif.; Mex. 

 L. Son. Ja-D. 



3. ACERATES Ell. GREEN MILKWEED. 



Perennial caulescent herbs. Leaves opposite or alternate. Flowers perfect, 

 regular, umbellate. Calyx small, usually with 2 glands in the sinuses of the 5 

 acute lobes. Corolla rotate; lobes 5, reflexed in anthesis. Hoods mostly at- 

 tached over the short or obsolete column, erect, involute-concave, saccate at the 

 base, entire, emarginate, or 2- or 3-toothed at the apex, with broad auricles at 

 the base, without horns or crests within. Follicles fusiform. Seeds with a coma. 



Auricles of the hoods when present, concealed within; leaves oval to linear. 



Umbel solitary, terminal; plant hirsute. 1. A. lanuginosa. 



Umbels several, lateral; plant glabrate or tomentose when young. 2. A. viridiflora. 

 Auricles of the hoods conspicuously spreading; umbels lateral; leaves narrowly linear. 

 Hoods emarginate or truncate at the summit, crestless within; umbels distinctly 



peduncled. 3. A. auriculata. 



Hoods trilobed at the summit, with an internal crest-like midrib terminating in the 

 middle lobe; umbels subsessile or on very short peduncles. 4. A. angusti folia. 



