WATER MILFOIL FAMILY 169 



abundant 8-ribbed capsules is the var. incerta Jepson, de- 

 scribed from the Yosemite Valley. Hetch Hetchy Valley 

 yields the var. congdonii Jepson, a rather tall form with 

 loosely hairy buds, and very distinct, slender calyx-tips. 



8. CLARKIA. 



1. C. rhomboidea Dougl. Leaves alternate (or the lower 

 opposite), oblong to ovate, entire, 

 ]/2 to V/2 in. long, *4 to Y in. wide, 

 on petioles ^ to ^ in. long. 

 Flowers distant in terminal ra- 

 cemes. Buds nodding. Calyx- 

 tube obconic above the ovary, 

 short. Petals purple, Y^ to y 2 in. 

 long, narrowed below to a broad 

 toothed claw. Capsule nearly ses- 

 sile, 4-angled, slightly curved, 1 

 in. long. (Phaeostoma rhomboidea 

 Nels.) 



The Clarkia is a slender, erect annual with pretty purplish 

 flowers. Although nowhere abundant, it is widely distributed 

 throughout the lower part of the Yellow Pine Belt. 



9. BOISDUVALIA. 



Erect rigid annuals, with alternate sessile leaves and small 

 flowers in leafy-bracted spikes. Petals purple, obovate, 2- 

 lobed. Calyx-lobes erect, deciduous. Capsule 4-celled, sessile. 



1. B. densiflora Wats. Plant 1 to 2 ft. high, soft-pubescent. 

 Leaves lanceolate, 1 to 2 in. long. Flowers in a dense spike, 

 each in the axil of an ovate acute bract Y> in. or so long. 

 Partitions of the capsule persisting on the central axis. — On 

 low ground of Yosemite Valley, Hetch Hetchy, etc. 



2. B. stricta Greene. Similar, but leaves and bracts, linear 

 and the flowers not crowded. Partitions of the capsule per- 

 manently attached to the walls. — Hetch Hetchy Valley; per- 

 haps common at low altitudes. 



HALORAGIDACEAE. Water Milfoil Family. 

 Aquatic or marsh plants with inconspicuous flowers sessile 

 in the axils of leaves or bracts. Ovary inferior, the fruit 1 to 

 4-celled, with 1 seed in each cell. 



1. HIPPURIS. Mare's Tail. 

 1. H. vulgaris L. A simple-stemmed erect herb, y 2 to 2 

 ft. high. Leaves in whorls of 6 to 12, linear, entire, acute, % 



