238 



marked wing on the lobes which runs into the apical notch and 

 all around the margins, 15-1; mm. long and i-ijmm. broad. The 

 fruit is thinner than in C. verna, and the lobes less divergent, the 

 groove about as deep. Collected by Prof. E. L. Greene near 

 Donner Lake, Sierra Nevada, California. 



9 C. Bolanderi. Hegelm. Verhand Bot. Brand 10, 114 (1868 ?). 

 Usually more branching, with larger stems and leaves than in 

 C. verna, but similar to that species in general appearance and 

 habit. Floating leaves obovate or rhombic-obovate. Fruit or- 

 bicular or slightly obovate, i-t i^ mm. in diameter, or sometimes 

 a little longer than broad, the lobes scarcely winged, with sharp 

 or obtuse closely approximated margins. Styles twice as long as 

 the fruit, erect, persistent or subpersistent. A Pacific coast plant, 

 occurring at Vancouver's Island, and other places in British 

 Columbia, Oregon, (Hall No. 460), Washington, Placer County, 

 (Bolander) and other places in Cahfornia. 

 10. C. aiLhtmnalis. L. Sys. Nat. 2, 52, No. 13(1767). 

 C. angiistifolia. Hoppe. Bot. Tasch. 155 (1792)- 

 C. virens. Gold. Act. Mosq. 5, 119 (18 17). 

 Plant entirely submerged, very bright green when fresh, often 

 growing in rapids. Leaves entirely destitute of stellate scales, 

 crowded on the stem, hnear-lanceolate, broader and clasping at 

 the base, retuse or bifid at the apex, one- nerved, 10-15 mm. long. 

 Styles about as long as the fruit, reflexed and soon deciduous. 

 Fruit sessile or occasionally on a minute peduncle, slightly nar- 

 rower than long, or orbicular, 1-2 mm. in diameter, the lobes with 

 a deep groove between them which extends halfway to the centre 

 of the fruit, and broad wings on the margins. 



Extensively diffused in northern regions. Common in Can- 

 ada and British Columbia. It occurs in western Massachusetts, 

 (Gr. Man. Ed. 6) Lake Champlain (Pringle), Sault Ste. Marie 

 (Morong), South Colorado (Brandegee), and Harney Valley, 

 Oregon (Howell). 



II. C.peploides. Nutt. Trans. Phil. Soc. n. s. 5, 141 (1837). 

 C. Dricmmondi. Hegelm. Monog. 60 (1864). 

 A small species, creeping in mats 2-4 cm. upon moist 

 ground, often under the shade of dwelling houses. Leaves all 

 obovate or oblanccolate, 2-5 mm. long, Yz-lYi mm. broad, the 



