ASCLEPIADACEAE (MILKWEED FAMILY) 387 



with small auricles at base much involute and concealed, alternated by as 

 many short and roundish or gland-like, small internal teeth: anther-wings 

 semi-rhomboid above, with a much longer tapering base. From Colorado to 

 the Saskatchewan and eastward across the continent. 



\2a. Acerates viridiflora Ivesia Brit. Mem. Torr. Club 5: 265. 1894. Leaves 

 lanceolate or oblong-lanceolate, 5-12 cm. long. Same range and often with 

 the species. 



26. Acerates viridiflora linearis Gray, Syn. Fl. 2: 90. 1878. Leaves 

 elongated-linear, stems low, and umbels usually solitary. New Mexico to 

 Canada. 



3. Acerates angustifolia (Nutt.) Dec. in DC. Prodr. 8: 522. 1844. Stem 

 puberulent but foliage glabrous, slender, 3-5 dm. high, simple: leaves long 

 and narrowly linear, with scabrous and more or less revplute margins and a 

 strong midrib; the upper alternate and the lower opposite: umbels several, 

 10-15-flowered; flowers greenish: hoods whitish, erect, equaling the anthers, 

 conduplicate-concave, the base of each inner margin appendaged by a cuneate, 

 erosely truncate lobe, the apex 2-lobed and the narrow internal crest exserted 

 in the sinus in the form of an intermediate tooth; interior crown of 5 very 

 small 2-lobed processes between the bases of the anthers: follicles long- 

 acuminate, erect on the ascending pedicel. Acerates stenophylla Decaisne. 

 From Colorado and Nebraska to Texas. 



2. ASCLEPIAS L. MILKWEED 



Herbs with erect or merely spreading stems, opposite or sometimes verticil- 

 late or alternate leaves, and terminal and lateral umbellate inflorescence. 

 Calyx 5-parted, commonly bearing some minute processes at the base within. 

 Corolla rotate, 5-parted, dextrorsely valvate-convolute in the bud; crown 

 consisting of 5 distinct cucullate or hollowed, nectariferous appendages, op- 

 posite the anthers, that are involute or complicate and bearing a horn or crest- 

 like process from the back or toward the base within, either sessile or elevated 

 on a column which is shorter than the anthers. Anthers tipped with an in- 

 flexed or sometimes erect membrane; the polliniferous cells lower than the 

 stigma; pollen masses suspended, attached in pairs to the glands of the 

 stigmatic ring. 



Corolla and crown orange or bright red. 



Leaves nearly all alternate; corolla orange . . . 1. A. tuberosa. 



Leaves opposite; corolla red . 2. A. incarnata. 



Corolla greenish, purplish, yellowish, or white. 

 Leaves lanceolate or broader (not linear). 



Leaves sessile, very broad (suborbicular), soon glabrous. 



Horns concealed; leaves obtuse . . . . 3. A. cryptoceras. 



Horns exserted; leaves retuse . . . . . 4. A. latifolia. 



Leaves petioled, lanceolate or broader, canescent or tomen- 



tose, or in No. 7 nearly glabrous. 



Leaves obtuse; follicle with soft spinose processes . . 5. A. speciosa. 

 Leaves lanceolate or obovate; follicle without spinose- 



processes. 

 Leaves obovate-retuse, densely tomentose-canescent . 6. A. arenaria. 



Leaves lanceolate, glabrate 7. A. Hallii. 



Leaves linear. 



Leaves opposite . . . . . . . . 8. A. brachystephana. 



Leaves verticillate or scattered. 



Plant tall, 4-6 dm. high; leaves verticillate. 



Hoods entire . . . . . . . 9. A. verticillata 



Hoods dorsally hastate-sagittate . . . . . 10. A. galioides. 



Plant low, 1-2 dm. high; leaves crowded, filiform-linear . 11. A. pumila. 



1. Asclepias tuberosa L. Sp. PI. 217. 1753. Hirsute or roughish-pubescent, 

 4-8 dm. high, very leafy to the top: leaves lanceolate-oblong to linear- 

 lanceolate, sessile or slightly petioled: umbels several and mostly cymose at 

 the summit of the stem: hoods narrowly oblong, erect, deep bright orange, 

 much surpassing the anthers, almost as long as the purplish- or slightly 

 greenish-orange, oblong corolla-lobes, nearly equaled by the filiform-subulate 



