MILKWEED FAMILY 183 



Leaves broadly oval or rectangular-oval or nearly orbicular, obtuse or 

 retuse at both ends; umbels sessile. 

 Plant puberulent when young, glabrate in age; column very short. 



5. A. la ti folia. 

 Plant tomentulose; column half as long as the anthers. 



6. A. arenaria. 

 Leaves ovate or lanceolate, or rarely oval, acute. 



Leaves ovate or ovate-lanceolate, more or less tomentose, at least when 

 young. 

 Hoods truncate, slightly longer than the anthers; leaves sessile, 



with rounded or subcordate bases. 7. A. erosa. 



Hoods ovate-oblong to lanceolate, much exceeding the stamens; 

 leaves petioled. 

 Corolla yellowish; hoods with a tooth on each margin, not- 

 auricled or gibbous at the base; peduncles shorter than the 

 pedicels. 8. A. ovalifolia. 



CoroUa purple; hoods without teeth; peduncles longer than the 

 pedicels. 

 Hoods not auricled or gibbous at the base; leaves permanently 



tomentose, at least beneath. 9. A. curvipes. 



Hoods with two gibbosities at the base; leaves puberulent 

 when young, glabrous in age. 10. A. Hallii. 



Leaves linear-lanceolate; hoods truncate, httle if at all longer than the 

 anthers. 

 Column short; leaves pale. 



Plant more or less tomentose or puberulent, at least when yovmg. 

 Hoods shorter than the anthers; corolla purple; leaves in 

 age glabrate or nearly so. 

 Hoods about half as long as the anthers ; umbels ped uncled. 



11. A. brachystephana. 

 Hoods only slightly shorter than the anthers; umbel sub- 

 sessile. 12. A. uncinalis. 

 Hoods longer than the anthers; corolla purphsh outside, 

 green within; leaves permanently tomentose. 



13. A. macrosperma. 

 Plant glabrous; corolla greenish white; hoods white. 



14. A. labriformis. 

 Column more than half as long as the anthers; corolla purple. 



15. A. incarnata. 

 Leaves narrowly linear, verticillate or scattered. 



Corolla usually ash-colored; leaves 4-S mm. wide. 16. A. mexicana. 



Corolla greenish and wliite; leaves 1-3 mm. wide. 



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



Hoods entire. 17. A. verticillata. 



Hoods dorsaUy hastate-sagittate. 18. A. galioides. 



Plant low, 1-2 dm. high, bushy, from a ligneous base; leaves scattered, crowded. 



19. A. pumila. 



5. ASCLEPIODORA A. Gray. Spider Milkweed. i. .4. decumbens. 



Family 107. CONVOLVULACEAE. Morning-glory Family. 



.styles distinct or partly so. 



Corolla not plaited: styles simple. 1. Cress.\. 



Corolla plaited: styles 2-cleft. 2. Evol\'TjLU3. 

 Styles united up to the stigmas. 



Stigmas subglobose. 3. Ipomoea. 



Stigmas linear to oblong-cylindric. 4. Convolvulus. 



1. CRESSA L. 



Stem erect: pedicels longer than the leaves. 1. C. erecta. 



Stem decumbent; pedicels shorter than the leaves. 2. C. depressa. 



2. EVOLVULUS L. l. E. Nuttallianus. 



3. IPOMOEA L. Morning-glory. 



Plant bushy, not climbing; leaves linear. 1. I. leptophylla. 



Plant climbing: leaf-blades cordate. 2. /. purpurea. 



4. CONVOLVULUS (Tourn.) L. Bindweed, Morning Glory. 



Calyx not closely subtended by the bracts. 



Plant not canescent: leaf-blades hastate, but otherwise entire. 



Whole plant glabrous or nearly so 1. C arvensis. 



Stem and lower surface of the leaves with scattered long hairs. 



2. C. ambigcns. 

 Plant more or less canescent: leaves usually lobed or dissected. 



Main divisions of the leaf-blades ovate or oblong, obtuse, lobed; sepals auricled 

 at the base 3. C. herrnannioides. 



