ASCLEPIADACEAE 943 



2a. Asclepias Rolfsii Britton. Similar to the two preceding species in habit. Leaves 

 rather numerous ; blades ihinnish, mainly oblong, sometimes narrowly so, when broad 

 often fiddle-shaped, truncate or cordate at the base : umbels in terminal leafv- cymes : 

 calyx-lobes nearly ^ as long as the corolla-lobes, pubescent : corolla orange ; lobes oblong, 

 6-7 mm. long : "column stout : hoods erect, broadly oblong, 5-6 mm. long, considerably 

 exceeding the horns. 



In pine lands, southern peninsular Florida. Spring and summer. 



3. Asclepias Curtissii A. Gray. Stems decumbent or suberect, 5 dm. long or more, 

 from a much thickened tuberous rootstock, simple or branched, puberulent, purplish : 

 leaf-blades broadly oblong or some round-oblong, 3-5 cm. long, truncate, rounded or 

 some of the lower ones acutish at the base, apiculate or retuse at the apex, glabrous : 

 umbels 2-several in the axils of the upper leaves, many-flowered, on peduncles 2-4 cm. 

 long : pedicels very slender, 1-1.5 cm. long, puberulent : corolla greenish, purple-tinged on 

 the outside ; lobes 6 mm. long, oblong-lanceolate : column scarcely apparent : hoods erect, 

 distinctly stalked, white, the keel purple-tinged, 5 mm. high, exceeding the anthers, acute 

 at the apex, the ventral margins rounded and infolded, distinctly clawed at the hastate base : 

 horn short, subulate, affixed to about the middle of the hood, horizontally exserted and 

 incurved over the anthers : anther-wings very short, triangular-sagittate, angled and sharply 

 salient at the entire base : follicles 1 dm. long, long-attenuate at the apex, puberulent : seeds 

 8 mm. long, erose-undulate on the margin : coma 3 cm. long. 



In sandy soil in the scrub, Florida. Spring to fall. 



4. Asclepias latifolia (Torn) Raf. Stems usually simple, 3-8 dm. high, stout, 

 minutely puberulent when young, glabrous when old, very leafy : leaf-blades broader than 

 long, commonly broadly emarginate and mucronulate at the apex and cordate or subcordate 

 at the base, 7-15 cm. long and nearly as wide, the primary nerves notably wide-spreading : 

 umbels 2-4 or more, short-ped uncled in the axils of the upper leaves and rarely terminal, 

 many-flowered, often 8 cm. in diameter : pedicels canescent, nearly 3 cm. long : corolla- 

 lobes ovate, acute, 7-9 or 10 cm. long, greenish : column short and thick : hoods truncate, 

 about equalling the anthers, the horn broadly triangular, the exserted subulate apex pro- 

 jecting over the acute ventral sides of the hood and exserted over the stigma : anther-wings 

 notched or somewhat auriculate, spreading at the base : follicles erect ondeflexed pedicels, 

 ovoid, acutish, 6 cm. long, glabrate : seeds 8 mm. long, glabrous, marked with fine broken 

 ridges and dots, the wing-like margin narrow : coma rather stiff, 2.5-3.5 cm. long. 



On dry plains, Kansas to Colorado, Texas and Arizona. Summer and fall. 



5. Asclepias amplexicaulis J. E. Smith. Stems glabrous, 3 dm. to 1 m. high : 

 leaves opposite or rarely in fours at the base of the stem ; blades sessile, oblong or elliptic, 

 6-12 cm. long, 3.5-8 cm. wide, clasping at the base, rounded, retuse and apiculate at the 

 apex, wavy-margined, glabrous, lighter and glaucous beneath : peduncles much longer than 

 the leaves, terminal, solitary or rarely two : umbels loosely many-flowered : pedicels 

 slender, 2-3 cm. long : flowers rather large and showy : corolla-lobes greenish or dull 

 greenish purple, 6-10 mm. long, acutish : hoods erect, flesh colored or reddish, sessile at the 

 summit of the short column, slightly gibbous or saccate at the base, truncate at the undu- 

 late-erose and toothed summit, as high as or somewhat exceeding the anthers : horn falcate, 

 angled above the middle, strongly inflexed and attenuated at the long-exserted apex : anther- 

 wings conspicuously bicorniculate at the base : follicles 10-16 cm. long, acute or long-atten- 

 uate : seeds 7 mm. long, glabrous, marked with minute broken lines, the margins rather 

 broad, paler than the body : coma 5 cm. long or more, very soft and silky. [A. obtusifolia 

 Michx. ] 



In dry or sandy soil, New England to Nebraska, Florida and Texas. Spring and summer. 



6. Asclepias humistrata Walt. Stems glabrous and glaucous throughout, decumbent 

 from a long tuberous root, simple or branched above, stout and thick, succulent, 3-6 dm. 

 long : leaves rather crowded, usually decreased in size at the base or toward the summit of 

 the stem, the successive pairs parallel ; blades sessile, vertical, nearly alike on both sides, 

 ovate, 5-13 cm. long, 4-10 cm. wide, cordate-clasping and somewhat auriculate at the base, 

 obtuse at the apex, thick and succulent when fresh, becoming thin and papery when dry, 

 sometimes undulate on the margins, the whitish transverse and reticulated veins turning 

 reddish : peduncles as long as or commonly shorter than the leaves : pedicels slender, about 

 2 cm. long : corolla-lobes dull greenish purple, 7 mm. long : column short : hoods whitish, 

 about 5 mm. high, obovate-truncate, rounded at the apex, the ventral margins with a broad 

 rounded tooth on each side about the middle : horn broad, flat, angular-arcuate, only 

 slightly exceeding the hood : anther-wings obscurely notched at the base : follicles 1-1.5 

 dm. long, 1.5-2 cm. wide, attenuated and acutish at the apex, glabrous and glaucous : 



