RANUNCULACEAE (BUTTERCUP FAMILY) 189 



1. Nymphaea polysepala (Engelm.) Greene, Bull. Torr. Bot. Club 15: 84. 

 1887. Petioles stout, the floating leaves oval, with narrow or nearly closed 

 sinus, 1-3 dm. long: calyx sub globose, when fully expanded 8-12 cm. broad; 

 sepals 9-12, yellow, or at length tinged with red: petals 12-18, obovate, cu- 

 neate, truncate: fruit subglobose, with a constricted neck and convex um- 

 bonate 15-24-rayed stigmatic disk. High mountain lakes; Colorado, Wyoming, 

 and northwestward. Nymphaea (Nuphar) advena, reported from Wyoming, 

 is probably this species. 



44. CERATOPHYLLACEAE L. HORNWORT FAMILY 



Aquatic herbs, with whorled finely dissected leaves, and minute axillary 

 and sessile monoecious flowers without floral envelopes, but with an 8-12-cleft 

 involucre in place of a calyx. Fertile flower a simple 1-celled ovary. 



1. CERATOPHYLLUM L. 



Submersed plants, in ponds or slow flowing streams, the sessile leaves cut 

 into thrice-forked thread-like divisions. Sterile flowers of 12-24 stamens, 

 with sessile anthers. Fruit an achene, beaked with a slender persistent style. 



1. Ceratophyllum demersum L. Sp. PL 992. 1753. Stems very slender, 

 3-5 dm. long: leaves in numerous whorls of 6-8: achene elliptical, shortly stipi- 

 tate, with a short spine or tubercle on each side near the base. California and 

 northward, thence eastward across the continent. 



45. RANUNCULACEAE Juss. BUTTERCUP FAMILY 



Herbs or rarely climbing shrubs with acrid sap. Leaves usually alternate, 

 simple or compound, without stipules but often dilated at base of petioles. 

 Flowers regular or irregular, the parts all distinct and free. Sepals 3-15, often 

 petal-like, usually caducous, imbricate (in two genera valvate). Petals 3-15, 

 or wanting. Stamens numerous or rarely few. Pistils many, few, or solitary, 

 becoming achenes, follicles, or berries. 



Pistils becoming follicles or berries with several seeds. 

 Flowers regular. 



Leaves simple (sometimes deeply lobed or divided); follicles 



many, forming a head in fruit. 

 Leaves undivided . . . . . . . . .1. Caltha. 



Leaves deeply lobed or divided 2. Trollius. 



Leaves compound. 



Petals not spurred; fruit a berry 3. Actaea. 



Petals spurred; fruit follicular 4. Aquilegia. 



Flowers irregular; carpels 3-5. 



Posterior (upper) sepal spurred ....... 5. Delphinium. 



Posterior sepals hooded (helmet-like) ...... 6. Aconitum. 



Pistils becoming achenes. 



Petals none or inconspicuous; sepals large and petal-like. 

 Flowers subtended by an involucre; sepals imbricated. 



St; vies short, glabrous or pubescent 7. Anemone. 



Styles becoming elongated and plumose .... 8. Pulsatilla. 



Flowers without involucre; sepals valvate; styles elongated and 



plumose; leaves opposite ....... 9. Clematis. 



Petals as well as sepals present, except in the last. 



Minute animals: sepals spurred ....... 10. Myosurus. 



Perennials; sepals not spurred. 



1 louers white 11. Batrachium. 



Flowers yellow; or petals wanting. 



Leaves simple but often lobed or divided; petals with a nec- 

 tariferous pit at the base; achenes compressed. 



Achenes smooth or hispid; petals broad . . . .12. Ranunculus. 

 Achenes longitudinally striate; petals narrow . . 13. Halerpestes. 



Leaves ternately compound or decompound. 



Petals present 14. Cyrtprhyncha. 



Petals wanting . . . . . . . . .15. Thalictrum. 



