250 CONTRIBUTIONS FEOM THE NATIONAL HERBARIUM. 



KEY TO THE SPECIES. 



Mature carpels with a whitish, cellular or cartilaginous, cupulate 

 border around the laterally compressed keel. 

 Scapes elongated, CO to 120 mm. long; heads of achenes 30 to 40 

 mm. long; beaks not exceeding the diameter of the back 



of the achene 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. M. egglestonii. 



Carpels not with a cupulate border. 



Achenes flat on the back, tipped with a very short appressed 



beak, or this wanting 3. 31. minimus. 



Achenes strongly carinate, tipped with a long subulate ascend- 

 ing beak 4. M. aristatus. 



1. Myosurus cupulatus S. Wats. Proc. Amer. Acad. 17: 362. 1882. 



Type locality: "Arizona, hills between the Gila and San Francisco rivers." 



Range: Arizona and New Mexico. 



New Mexico: Bsar Mountain; Hillsboro. Wet soil, in the Upper Sonoran Zone. 



2. Myosurus egglestonii Woot. & Standi. Contr. U. S. Nat. Herb. 16: 123. 1913. 

 Type locality: 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. 



3. Myosurus minimus L. Sp. PI. 284. 1753. 



Type locality: "Habitatin Europae collibus apricis aridis." 

 Range: 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. 



Type locality: "Moist places in the Cordillera of Chili at Los Patos, Province of 

 Coquimbo, elev. 11,200 feet above the level of the sea." 



Range: 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 S. F. Gray. Water crowfoot. 



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 1. B. drouetii. 



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. triehophyllum. 

 Segments of the leaves longer, 15 to 30 mm. long, flaccid, 



collapsing when withdrawn from the water 3. B. Jlaccidum. 



