232 CALLITRICHACEAE. 



305. CALLITRICHE. Water Starwort. 



Low slender usually tufted herbs; leaves spatula te or linear or 

 both, entire; flowers monoecious, solitary or 2 or 3 in the axil of 

 a leaf, with or without a pair of membranaceous bracts; stami- 

 nate flower a single stamen; pistillate flower a single 4-celled 

 ovary, sessile or pedicelled, with 2 distinct sessile stigmas. 



Leaves all submersed, linear, 1-nerved. C. autumnalis. 



Floating leaves obovate-spatulate, 3-nerved. 



Styles about as long as the fruit. C. palustris. 



Styles twice as long as the fruit. C. bolanderi. 



Callitriche autumnalis L. Leaves all submersed, linear, 1-nerved, retuse 

 or bifid at apex; fruit orbicular, retuse, the two carpels separate nearly to 

 the axis. 



In flowing water, rare. 



Callitriche palustris L. Aquatic or growing in the mud; floating leaves 

 obovate, obtuse or emarginate, the others linear or spatulate, 1-nerved, 1-2 cm. 

 long; when terrestrial, leaves all linear; bracts 2, as long as or longer than the 

 fruit or wanting; fruit oval, emarginate, 1 mm. long, the edges grooved and 

 narrowly winged; styles erect, shorter than the fruit. 



Not rare, in ponds and pools. 



Callitriche bolanderi Hegelm. Floating leaves rhombic-obovate; fruit 

 orbicular, usually obcordate, tipped with the much longer styles. 

 In still ponds, common. 



Family 55. EMPETRACEAE. Crowberry Family. 

 Low evergreen heath-like shrubs; flowers small, dioecious or 

 polygamous, axillary or in terminal heads ; sepals 3 ; petals 2 or 3 

 or none; stamens 3; style short; ovary 2-several-celled, sessile, 

 the style cleft into as many stigma-bearing segments as there are 

 cells of the ovary ; ovules 1 in each cell ; fruit a berry-like drupe 

 with 2-several seed-like nutlets. 



306. EMPETRUM. Crowberry. 



Low spreading shrubs; flowers polygamous, scattered and 

 solitary in the leaf-axils, inconspicuous, scaly-bracted ; calyx of 

 3 spreading somewhat petal-like sepals; style very short; stigmas 

 6-9-rayed; fruit a berry-like drupe. 



Empetrum nigrum L. Crowberry. Branches procumbent, 5-25 cm. long; 

 leaves linear, obtuse, thick, 4-7 mm. long; berry black. 



Mount Rainier, Piper; Copalis, Conard; Vancouver Island, British Colum- 

 bia, Macoun. 



Family 56. LIMNANTHACEAE. False Mermaid Family. 

 Low annual herbs with alternate pinnate leaves, without 

 stipules; flowers perfect, regular, 3-6-merous, slightly peri- 



