164 American Midland Naturalist Monograph No. 7 



5. Stem, leaves, and capsules crisp-pubenilent; leaves 1-4 mm 

 wide; petals 3-5 mm long; wet ground, rare; known from 

 Jo Daviess, Lake, Lee, Mason, Peoria, and Winnebago 

 counties. Aug.-Sept. [E. lineare Muhl., nom. illegit. ; E. 

 densiim sensu auth., non Raf.] E. leptophyllum Raf. 



2. Jussiaea L. — Primrose-willow 



1. Stems erect; petals 5-10, rarely 12 mm long. 



2. Petals and calyx-lobes 4; stem winged; wet ground in the south- 

 ernmost counties, rare. July-Sept. /. dccurrens (Walt.) DC. 



2. Petals and caly.x-lobes 5; stem not winged; along river courses, 

 rare; known from Alexander, Jackson, and Randolph coun- 

 ties /. Icptocarpa Nutt. 



1. Stems creeping or floating; petals 10-15 mm long; muddy banks 

 or in water, not common; chiefly in s. 111., but also Vemiihon 

 and Mason counties. May-Sept. [/. diffusa Forsk.] /. repens L. 



3. Ludwigia L. — False Loosestrife 



1 . Leaves opposite, oval ; stems procumbent or floating ; petals small, 

 pink, or absent; capsules 4-sided, 3-4 mm long; muddy shores 

 and ditches, local. July-Aug. [hnardia palustns L.; L. palustris 



var. americana Fern. & Grisc] L. palustris (L.) Ell. 



1. Leaves alternate, elliptical; stem erect. 



2. Flowers short-stalked; petals yellow, conspicuous; capsules 

 cubical, 5-7 mm long, opening by a terminal pore; wet 

 ground, common. June-Sept. Seed-box [L. alternifolia var. 



pubescens Palmer & Steyerm.] L. alternifolia L. 



2. Flowers sessile, inconspicuous. 



3. Capsules turbinate, the calyx-lobes 3 mm long; petals minute, 

 greenish; ditches, swamps, muddy shores, locally through- 

 out 111. July-Sept L. polycarpa Short & Peter 



3. Capsules cylindrical, the calyx-lobes about 1 mm long; petals 

 none; swamps, s. 111., rare. July-Sept. [L. cylindrica Ell.] 

 - L. glandulosa Walt. 



4. Oenothera L. — Evening-primrose 

 1. Leaves not linear-filiform; stigma 4-lobed (only slightly in O. 

 serrulata) . 

 2. Calyx-lobes reflexed; stamens equal in length (e.xcept O. ser- 

 rulata) ; flowers more or less nocturnal; petals yellow; 

 capsules terete or round-angled; plants biennial or annual. 

 3. Hyjjanthium above the ovary 6-8 mm long; adv. from the 



west; Cook and Peoria counties O. serrulata Nutt. 



3. Hypanthium above the ovary at least 15 mm long, usually 

 much longer. 

 4. Capsules lanceoloid-cylindrical. 4-7 mm thick at maturity 

 (at least at base) . 



