250 CONTRIBUTIONS FROM THE NATIONAL HERBARIUM. 
KEY TO THE SPECIES. 
Mature carpels with a whitish, cellular or cartilaginous, cupulate 
border around the laterally compressed keel. 
Scapes elongated, 60 to 120 mm. long; heads of achenes 30 to 40 
mm. long; beaks not exceeding the diameter of the back 
of the achene. ...... 22.2... eee cece eee eee eee 1. M. cupulatus. 
Scapes short, less than 5 mm. long; heads 13 mm. long or less; 
beaks much exceeding the diameter of the back of the 
achenes........2.....22-2- wee eee eee eee eee ee eee e nee 2. M. egglestonii. 
Carpels not with a cupulate border. 
Achenes flat on the back, tipped with a very short appressed 
beak, or this wanting...............020202 02 2e cece eee ee 3. M. minimus. 
Achenes strongly carinate, tipped with a long subulate ascend- 
ing beak... 2.2... eee eee ec ee eee eee eeeeeee 4, M. aristatus. 
1. Myosurus cupulatus 8. Wats. Proc. Amer. Acad. 17: 362. 1882. 
Type Locauity: ‘Arizona, hills between the Gila and San Francisco rivers.”’ 
Range: Arizona and New Mexico. 
New Mexico: Bear Mountain; Hillsboro. Wet soil, in the Upper Sonoran Zone. 
2. Myosurus egglestonii Woot. & Stand]. Contr. U. 8S. Nat. Herb. 16: 123. 1913. 
TyPE Locatiry: On a mesa on the road between Tierra Amarilla and Park View, 
Rio Arriba County, New Mexico. Type collected by W. W. Eggleston (no, 6472). 
RanGE: Known only from type locality. 
38. Myosurus minimus L. Sp. Pl. 284. 1753. 
Type Locatiry: ‘Habitat in Europae collibus apricis aridis,”’ 
Rance: British America to California and Florida; also in Europe and Africa, 
New Mexico: Mimbres Valley; near Tierra Amarilla, Moist soil, in the Upper 
Sonoran Zone, 
4. Myosurus aristatus Benth. Lond. Journ. Bot. 6: 458. 1847. 
Tyre Locauity: ‘Moist places in the Cordillera of Chili at Los Patos, Province of 
Coquimbo, elev. 11,200 feet above the level of the sea.”’ 
Rance: Washington and Montana to California and New Mexico; also in South 
America, 
New Mexico: Tunitcha Mountains; Sandia Mountains, In mud, in the Transition 
Zone. 
7. BATRACHIUM §.F. Gray. WarTer crowroorT, 
Aquatic or subaquatic perennials with dissected submersed leaves having many 
filiform segments, and occasionally with a few dilated emersed ones; peduncles 
solitary, opposite the leaves; petals white; achenes not margined, rugose. 
KEY TO THE SPECIES, 
Flowers small, the petals less than 5 mm. long, oblong-obovate; 
stamens 5 to 12..... 222s 1. B. drouetit. 
Flowers larger, the petals 5 to 7 mm. long, broadly obovate; sta- 
mens numerous. 
Segments of the leaves rather short, 10 to 15 mm, long, 
scarcely collapsing when withdrawn from the water.. 2. B. trichophyllum. 
Segments of the leaves longer, 15 to 30 mm. long, flaccid, 
collapsing when withdrawn from the water........... 3. B. flaccidum, 
