87. Aristolochiaceae 167 



in Boone, Cook, Du Page, Lake, and McHcnry counties. 



[M. exalbcscens Fern.] M. spicatum L. 



3. Leaves chiefly scattered, or absent from the flowering stems; 



muddy shores and shaflow water, rare 



-- M. humile (Raf.) Morong 



2. Floral lea\es pinnatifid or pectinate; leaves verticillate in threes 



and lours; lakes and slow streams, local ...M. vcrlicillatum L. 



1. Carpels 2-keeled and roughened on the back; stamens 4. 



4. Floral leaves (bracts ) ovate or lanceolate, serrate; ponds and 



slow streams, local M. heterophyllum Michx. 



4. Floral leaves linear, pectinate; ditches and muddy shores, 



chiefly in w. 111. [M. scabratum Michx.] 



M. pinnatum (Walt.) BSP. 



2. Proserpinaca L. — Mermaid-weed 

 P. palustris L. Ponds and slow streams, locally throughout 111. July- 

 Sept. [P. palustris var. amblygona Fern.; P. palustris var. crebra Fern. 

 & Grisc] 



85. Callitrichaceae Lindl. 



1 . Callitriche L. — Water-starwort 

 1. Fruit short-pedimcled; bracts absent; plants terrestrial, growing on 

 moist soil, local; known from Champaign, Coles, Jackson, Ma- 

 coupin, St. Clair, and Wabash counties. [C. austini Engelm.] 



- - C. terrestris Raf. 



1. Fruit sessile; plants aquatic or amphibious. 



2. Fruit oval, flat, longer than the styles; in ponds and slow 



streams, very local C. palustris L. 



2. Fruit obovate, convex, shorter than the styles; locally through- 

 out 111. [C. Jurmaphroditica sensu auth., non L.] 



C. heterophylla Pursh 



86. Hippuridaceae Sagor. & G. Schneid. 



1. Hippuris L. — Mare's-tail 

 H. vulgaris L. Ponds and streams, rare; known from Kane, Lake, 

 and McHenry counties. June-Aug. 



87. Aristolochiaceae Bkmie — Birthwort Family 

 1. Stem prostrate, rooting at the nodes; flowers regular, 3-lobcd; calyx per- 

 sistent; stamens 12 1. Asarum 



1. Stem erect or twining; flowers very irregular, the calyx deciduous; stamens 

 6 2. Aristolochia 



1. Asarum L. — Wild Ginger 

 1. Calyx-lobes deltoid-ovate, shortly acuminate, scarcely longer than 

 the calyx-tube, spreading or reflexed at flowering time; woods, 

 common. Apr.-May A. rcflexum Bickn. 



