HALORAGK.E. ( WATER-MILFOIL FAMILY.) 99 



# * * Flowers perfect, secund upon the branches of a forked cyme, mostly yellow 



or yellowish: leaves very fleshy, entire. 



•*- Leaves narrowed toward the base, obtuse. 



3. S. debile, Watson. Stems weak, 2 to 4 inches high, from very slender 

 running rootstocks: leaves rounded or ohovate : flowers on rather long pedi- 

 cels, in small cymes. — Hot. King's Exp. 102. In the Wasatch and lintas: 

 also mountains of Nevada and X. California. 



H- +- Leaves broadest at base, acute. 



4. S. steriopetalum, Pursh. Stems 3 to 6 inches high, simple or some- 

 times branched : leaves narrowly lanceolate : flowers bright yellow, nearly sessile. 

 — Torr. & Gray, Fl. i. 5G0. Very common on both sides of the mountains 

 from Colorado to Montana and into Oregon. 



5. S. Douglasii, Hook. Stems 3 to 4 inches high, branching at base, 

 from a stout proliferous rootstock: leaves lanceolate or the lowermost linear- 

 subulate, membranaceous when dry: flowers sometimes polygamous, sessile: 

 follicles al length divaricately spreading from their united bases. — National Park, 

 W. Montana, Oregon, and California. 



Order 29. HALORAGEiE. (Water-Milfoil Family.) 



Aquatic herbs, with inconspicuous and often apetalous flowers sessile 

 in the axil of leaves or bracts, calyx adnate to the ovary in fertile ones, 

 the fruit indehiscent and nut-like. 



1. Hippuris. Leaves linear, in whorls of 8 or 12. Flowers perfect. Calyx entire. Petals 

 none. Stamen ami cell of the ovary one. 



2 Myriophyllum. Immersed leaves pinnately dissected. Flowers monoecious or polyga- 

 mous. Farts of the flower iu fours. 



1. HIPPURIS, L. Mare's Tail. 



Calyx-tube globular. — Smooth : with erect simple leafy stems : leaves 

 entire : flowers solitary. 



1. H. vulgaris, L. Stems a foot or two high : leaves usually a half to an 

 inch long, but often much longer, especially the submerged ones : calyx hardly 

 a half-line long. — In shallow ponds throughout the northern part of the con- 

 tinent, and southward in the Rocky Mountains to New Mexico. 



2. MYRIOPHYLLUM, L. Water-Milfoil. 



Limb of the calyx 4-lobed in the sterile flowers, wanting or minutely toothed 

 in the others. Petals 2 to 4, minute or wanting in the pistillate flowers. 

 Stamens 8 (in ours). Ovary 4-celled : stigmas recurved and plumose. — 

 Smooth leafy herbs : leaves whorled in threes or fours : upper flowers usually 

 staminate, the lower pistillate, and the intermediate ones perfect. 



1. M. spicatum, L. Leaves all pinnately parted and capillary, except 

 the floral ones or bracts; these ovate, entire or toothed, and chiefly shorter than the 

 flowers, which thus form an interrupted spike. — In the Atlantic States and 

 across the continent. 



