50 NORTH AMERICAN FLORA [Volume 25 



sessile. Flowers borne in umbel-like or rlichotomous cymes, the stalks not jointed. Sepals 5, 

 herbaceous or petaloid, the inner ones often slightly narrower than the outer ones. Petals 5, 

 yellow or purplish, and rarely darker at the base, deciduous, broadened upward. Stamens 10, 

 the filaments united into a tube at the base. Ovary mostly elongate ; styles filiform or sub- 

 ulate. Capsule columnar to oblong, or decidedly narrowed upward, prismatic, erect. 

 Seeds transversely ridged, the ridges sometimes broken up into tubercles. 

 Type species, O.vctlis comiculata L. 



Herbs. 



Longer filaments not appendaged on the back. 

 Sepals herbaceous. 



Blades of the leaflets obdeltoid in outline, with 2 divergent lobes. 



Blades of the leaflets notched at the apex or to above the middle ; pedicels pubescent. 

 Pedicels appressed-pubescent. 



Rootstocks with merely fibrous roots, or plants sometimes with a slender taproot. 

 Longer filaments glabrous. 



Stem appressed pubescent, usually copiously so ; capsules pubescent. 

 Corolla pale- or light-yellow ; petals 5-10 mm. long. 1. X. stricta. 

 Corolla golden-yellow ; petals 12-18 mm. long. 2. X. lexana. 



Stem loosely pubescent, often nearly glabrous ; 

 capsules glabrous, except in X. comiculala. 

 Plants erect. 



Cymes open in fruit ; leaves bright-green. 3. X. Bushii. 



Cvmes cluster-like in fruit; leaves reddish or 

 purplish. 4. X. rufa. 



Plants spreading and creeping. 5. X. comiculata. 



Longer filaments pubescent. 

 Petals glabrous. 



Plants creeping. 6. X. Langloisii. 



Plants erect, but sometimes with decumbent 

 branches. 

 Stems pubescent, but neither villous nor hir- 

 sute. 

 Corolla pale- or light-yellow ; sepals 5-4 mm. 

 long. 

 Cymes typically 1-flowered ; leaves nu- 

 merous ; leaflets small, 4-8 mm. wide. 7. X.filipes. 

 Cvmes typically several-flowered ; leaves 

 "few; leaflets "large, 10-16 mm. wide. 8. X. Brittoniae. 



Corolla golden-yellow ; sepals 5-6 mm. long. 9. X. man an tlia . 

 Stems villous or hirsute , sometimes sparingly so. 



Cymes dichotomous. 10. X. interior. 



Cymes umbel-like. 



Capsules columnar, about 2 mm. thick ; 

 sepals less than one fourth as long 

 as the capsule. 

 Corolla light-yellow ; petals 8-11 mm. 



long. 11. -V. colorea. 



Corolla golden-yellow ; petals 12-15 

 mm. long. 12. X. recurva. 



Capsules oblong, about 3 mm. thick ; 

 sepals about one half as long as the 

 capsule. 

 Petals pubescent. 

 Rootstocks arising from an elongate tuberous root or bear- 

 ing fusiform tuberous roots at internodes. 

 Capsules longer than the pedicels. 

 Capsules shorter than the pedicels. 

 Pedicels 1 oosely pubescent. 



Cyme umbel-like ; capsules densely pubescent. 

 Capsules longer than the pedicels. 

 Capsules shorter than the pedicels. 

 Cyme dichotomous ; capsules glabrous or thinly pubescent. 

 Capsule-body several times longer than the sepals ; 



leaflets uniformly green. 

 Capsule-body scarcely twice as long as the sepals ; 

 leaflets brown-margined. 

 Blades of the leaflets notched to below the middle or sometimes 

 to near the base ; pedicels glabrous. 

 Blades of the leaflets cuneate to obovate, notched at the apex, the 

 lobes erect. 22. X. vulcanicola. 



Sepals petaloid. 23. X. madrensis. 



Longer filaments appendaged on the back. 24. X. crassicaulis. 



Shrubs. 



Blades of the leaflets rounded or emarginate ; petioles and peduncles hirsute. 25. X. i lemaiodes. 

 Bladesof the leaflets acuminate; petioles and peduncles minutely strigillose. 26. X. acuminata. 



