704 Onagraceae Oenothera 



Bracts of inflorescence conspicuous in the bud, tending to be persistent 

 and foliaceous in fruit; inflorescence and capsules hirsute and 

 sti'igose; branches of inflorescence tending to be long and simple; 

 capsules scarcely beaked, mostly 2.5-3.5 mm long; leaves thickish. 



1.0. pycnocarpa. 



Bracts of inflorescence inconspicuous, deciduous soon after anthesis; in- 

 florescence and capsules subglabrous; branches of inflorescence tend- 

 ing to be numerous and short, fastigiate; capsules narrowed into a 

 beaklike tip with dilated apex, usually less than 2.5 cm long; leaves 



thin 2. 0. nutans. 



Stems angled, densely strigose and hirsute, grayish; leaves subcanescent ; 

 hypanthium, sepals, capsules, and branches of inflorescence canescent- 



strigose, scarcely if at all glandular-pubescent 3. O. canovirens. 



Sepal-tips 1 not quite terminal, hence separate in the bud; seed mostly 1.8-2 



mm long 4. O. cymatilis. 



Capsules, when mature, 2-3 mm in diameter, more slender than those of the 

 preceding group, and essentially uniform their entire length; seeds not 

 angled. 

 Leaves denticulate or subentire; flowers in terminal spikes; seed indistinctly 



and shallowly pitted 5. 0. rhombipetala. 



Leaves sinuate-toothed or pinnatifid; flowers in the axils of foliage leaves; 



seed deeply and distinctly pitted 6. 0. laciniata. 



Stamens of two lengths; seeds not in two distinct rows, clustered, not crested; 

 capsules conspicuously angled or ridged. 

 Capsule on a stipe equaling or somewhat exceeding the permanently pubescent 

 body; hairs on the capsule appressed or curved inw T ardly. (See excluded 



species no. 468, p. 1077) O. fruticosa. 



Capsule sessile or the stipe shorter than the body, pubescent to glabrate, the 

 hairs straight. 

 Hairs of stems below the inflorescence spreading, usually 1-2.5 mm long (stems 

 rarely glabrate); leaves mostly 10-25 (35) mm wide; intemode of stem 

 and branches below the lowest flower usually longer than the one below 

 it; flowers usually subtended by foliaceous bracts; pubescence, if any, of 

 capsule and calyx tube straight and glandless; calyx tube 12-18 mm long; 

 petals of earlier flowers 20-25 mm long; capsules sessile or essentially so. 



7. O. pilosella. 



Hairs of stems below the inflorescence curved or appressed, usually less than 

 1 mm long; leaves mostly 5-15 mm wide; internode of stem and branches 

 below the lowest flower usually much elongated and much longer than the 

 one below it; flowers usually subtended by linear bracts; pubescence of 

 capsule and calyx straight, with glands; calyx tube 5-10 mm long; petals 

 of earlier flowers 5-18 mm long; capsules manifestly on stipes. 

 Petals of earlier flowers mostly 12-18 mm long ; buds and tip of inflorescence 

 erect or nearly so; inflorescence when in fruit much less than half the 



height of the plant 8. O. tetragona var. longistipata. 



Petals of earlier flowers mostly 5-9 mm long; buds and tip of inflorescence 

 nodding; inflorescence in fruit usually more than half the height of the 



plant 9. O. perennis. 



Flowers pink or white 10. O. speciosa. 



Plants without stems ll.O. triloba. 



1. Oenothera pycnocarpa Atkinson & Bartlett. (Rhodora 15: 83. 1913.) 



Map 1484. Evening-primrose. This is the common form of the Oenothera 

 biennis complex in Indiana. It is found throughout the state and in all 

 kinds of habitats. It and the next three species are regarded as obnoxious 



1 This species probably O. muricata of authors. 



