83. Onagraceae 163 



1. Stem nearly terete; leaves short-petioled, narrow; hypanthium 

 glabrous or nearly so; moist sandy soil, rare; Mason Co., 

 Brcndcl; Massac Co., GU'ason. June-Sept. [R. niariana var. 

 leiosperma Fern. & Grisc.] R. mariana L. 



83. Onagraceae Dumort. — Evening-primrose Family 

 {Epilobiaceae Vent.) 

 1. Flowers usually with 4 petals (rarely 5 or 0) ; sepals 4-6 (rarely apparently 

 only 2) ; stamens 4-12. 

 2. Fruit a many-seeded capsule openina; by valves or by a pore. 



3. Seeds with a tuft of silky hairs; flowers (in our species) not yellow 



1. Epilobium 



3. Seeds without hairs. 



4. Hypanthium scarcely or not at all extended beyond the ovary. 



5. Stamens 8-12, in two series 2. Jussiaea 



5. Stamens 4 3. Ludwigia 



4. Hypanthium conspicuously extended beyond the ovary into a tube 



4. Oenothera 



2. Fruit indehisccnt, deciduous; flowers pink 5. Gaura 



1. Flowers with 2 notched white petals, 2 sepals, and 2 stamens; fruit inde- 

 hiscent, obovoid, with hooked bristly hairs 6. Circaea 



1. Epilobium L. — Willow-herb 



1. Petals 1-2 cm long; stigma 4-lobed; stem 0.5-2 m tall. 



2. Stem puberulent or glabrous; leaves alternate, entire or denticu- 

 late; petals entire; stamens and style declined; edges of woods 

 and burned-over ground, local; known from Cook, Lake, 

 La Salle, McHenry, and Winnebago counties. June-Aug. 



Fireweed [Chamaenerion spicatum (Lam.) S.F.Gray] 



E. angustifolium L. 



2. Stem hirsute; leaves mostly opposite, sharply serrulate; petals 



notched, stamens and styles erect; moist ground, occasional; 

 adv. from Eur.; Chicago, Cook Co., /. A. Steyermark in 1948. 



June-Aug E. hirsutum L. 



1. Petals 3-8 mm long; stigma entire; stem 20-90 cm tall. 



3. Leaves lanceolate, denticulate; stems with deciuTent lines Irom 



the bases of the leaves. 

 4. Seeds 1-1.5 mm long; coma reddish-brown; moist ground, 

 local. Aug.-Sept E. coloratum Muhl. 



4. Seeds 0.5-1 mm long; coma white; moist ground, in the n. 



counties, not common. July-Sept E. adenocaulon Haussk. 



3. Leaves linear, or linear-lanceolate, mostly entire; no decurrent 

 lines on stem. 



5. Stem, leaves, and capsules copiously solt-]juhe.scent with short 



.straight hairs; leaves mostly 4-8 mm wide; petals 7-8 mm 

 long; seeds 2 mm long; wet groimd, rare; Lake, McHenry, 

 Peoria, Winnebago, and Woodford counties. July-Sept. 



[E. molle Torr., non Lam.; /:". dcnsum Raf.J 



E. strictum Muhl. 



