382 COXTRIBUTIOXS FEOM THE NATIONAL HERBARIUM. 



6. OENOTHERA L. 



1. Oenothera strigosa (Rydb.) Mack. & Bush. Evening-primrose. Rare; at low- 

 altitudes, on dry slopes; perhaps introduced. B. G. to Utah, Kans., and Minn. — 

 Plants biennial, 0.4 to 1 meter high, hairy; leaves spatulate or lanceolate, 5 to 10 

 cm. long, with low teeth; flowers sweet-scented, in leafy spikes; petals 12 to 20 mm. 

 long, pale yellow; capsule 2.5 to 3 cm. long, cylindric. 



7. ANOGRA Spach. 



1. Anogra nuttallii (Sw^eet) A. Nels. East entrance, on dry bluffs, Umbach. 

 B. C. to Colo, and Minn. (Oenothera albicaulis Nutt.) — Perennial, 30 to 60 cm. high, 

 branched, with whitish stems; leaves linear or linear-oblong, 3 to 10 cm. long, entire 

 or with distant teeth, finely hairy beneath; flowers sessile in the leaf axils; petals 

 about 2 cm. long, white, tarning pink; capsule 2 to 3 cm. long, cylindric. 



8. GATTRA L. 



1. Gaura coccinea L. Butterfly plant. Occasional on prairie or dry slopes at 

 east entrance. Mont, to S. Dak. and Mex. — Branched perennial, 10 to 40 cm. high, 

 hairy; leaves oblong or lanceolate, 1 to 3 cm. long, entire or shallowly toothed; 

 flowers in slender spikes; petals 4 to 6 mm. long, pink or red; fruit 4-angled, nutlikc, 

 5 to 7 mm. long. 



One of the most characteristic plants of the Great Plains region. 



9. BOISDU VALLA Spach. 



1. Boisduvalia glabella (Nutt.) Spach. East entrance, abundant about dried-up 

 pools on prairie. B. C. to Calif, and Sask. — Annual, 10 to 30 cm. high, simple or 

 branched, finely hairj' or nearly glabrous; leaves sessile, ovate, 7 to 17 cm. long, 

 acute, finely toothed or entire; flowers sessile in the leaf axils; petals 2 mm. long, 

 pink; capsule 5 to 7 mm. long. 



10. GAYOPHYTUM Juss. 



Slender branched annuals, glabrous or nearly so; leaves linear, entire; flowers 

 very small, in the leaf axils; capsule linear or club-shaped. — In general appearance 

 the plants resemble closely the annual species of Epilobium. 



Capsule several times as long as its stalk 1. G. racemosum. 



Capsule less than 3 times as long as its stalk 2. G. intermedium. 



1. Gayophytum racemosum Torr. & Gray. East entrance, on dry hills, Umbach. 

 Wash, to Calif., Colo., and S. Dak. — Stems 10 to 30 cm. high; leaves 1 to 2 cm. long; 

 petals white or pink, 1 mm. long; capsules 1 to 1.5 cm. long. 



2. Gayophytum intermedium Rydb. Dry slopes, at east entrance and Summit, 

 Umbach. Wash, to Calif., Colo., and Mont. — Stems 15 to 40 cm. high; leaves 1 to 4 



cm. long; petals 1.5 to 2.5 mm. long, pink, with yellow base; capsules 5 to 10 mm. 

 long. 



59. HALOEAGIDACEAE. Water Milfoil Family. 



Perennial aquatic herbs; leaves whorled; flowers small, green, sessile in the leaf 

 axils; fruit a nutlet. 

 Leaves mostly divided into threadlike lobes; flowers with 2 to 4 sepals and 2 to 4 small 



petals 1. MYRIOPHYLLTJM. 



Leaves entire ; sepals and petals none 2. HIPPTJRIS. 



1. MYRIOPHYLLUM L. 

 1. Myriophyllum spicatum L. Water milfoil. East entrance, in ponds, 

 Umbach. Alaska to Calif., N. Mex., Kans., Conn., and Newf.— Stems submerged, 

 branched; leaves in whorls of 4 or 5, 1 to 3 cm. long; floral leaves ovate, entire or 

 toothed, very, small. 



