40 CONTRIBUTIONS FROM THE NATIONAL HERBARIUM. 



1. POTAMOGETON L. Pondweed. 



Leaves all or only partly submerged, alternate, the blades broad or narrow; stipules 

 more or less united and sheathing; flowers spicate; sepals and stamens 4; ovaries 4. 



It is probable that we have more species in the State than are listed here. The 

 material is difficult of collection and is usually neglected by collectors. 



KEY TO THE SPECIES. 



Leaves of two kinds, floating and submerged. 



Submerged leaves with blades; floating leaves elliptic 1. P.amerieanus. 



Submerged leaves without blades; floating leaves oval 2. P. natans. 



Leaves all submerged, narrow, sessile. 



Stipules free; spike continuous; fruits few 3. P.foliosus. 



Stipules adnate to the petioles; spikes interrupted; fruits 



numerous 4. P. interior. 



1. Potamogeton americanus Schlecht. & Cham. Linntea 2: 220. pi. 6. J. 26. 1827. 

 Potamogeton lonchites Tuck. Amer. Journ. Sci. II. 6: 226. 1848. 



Type locality: North America. 



Range: In ponds and slow streams throughout North America except in the 

 extreme northern part. 

 New Mexico: Collected by Fendler (no. 837), probably about Santa Fe. 



2. Potamogeton natans L. Sp. PI. 126. 1753. 

 Type locality: European. 



Range : In still water throughout most of North America except the extreme north; 

 also in Europe and Asia. 



New Mexico: Tunitcha Mountains (Standley 7557). 



3. Potamogeton foliosus Raf. Med. Repos. N. Y. n. ser. 5: 354. 1808. 

 Potamogeton gramineum L. err. det. Michx. Fl. Bor. Amer. 1: 102. 1803. 

 Potamogeton pauciflorus Pursh, Fl. Amer. Sept. 121. 1814. 



Type locality: "Hab. in rivis affluente mari inundatis Carolinae inferioris." 

 Range: In streams and ponds nearly throughout North America. 

 New Mexico: Tularosa Creek near Aragon; Canada Creek at Ojo Caliente; Berendo 

 Creek. 



4. Potamogeton interior Rydb. Colo. Agr. Exp. Sta. Bull. 100: 13. 1906. 

 Potamogeton marinus occidentalis Robbins; S. Wats, in King, Geol. Expl. 40th 



Par. 5: 339. 1871. 

 Potamogeton filiformis occidentalis A. Benn. Ann. Cons. Jard. Geneve 9: 102. 1905. 

 Type locality: Colorado. 



Range : Ontario and Northwest Territory to Utah and New Mexico. 

 New Mexico: Farmington; Cedar Hill; Carlsbad; Roswell. 



The following species are represented by specimens the localities for which are 

 uncertain but are probably in New Mexico or adjacent Texas: 

 Potamogeton pectinatus L. Wright 1894. 

 Potamogeton pusillus L. Wright 1896. 



2. ZANICHELLIA L. Horned pondweed. 



Leaves linear, mostly opposite, with sheathing stipules; flowers monoecious, sessile, 

 axillary, the staminate ones consisting of a single stamen ; ovaries 2 to 5, forming oblique 

 oblong indehiscent nutlets in fruit. 



