OF ARTS AND SCIENCES. 361 



XXV. 



CONTRIBUTIONS TO THE BOTANY OF NORTH 

 AMERICA. 



By Asa Gray. 



Presented Jan. 9, 1878. 



1. Elatines Americance. 



§1. Crtpta, Seubert. Tsosteraones (di-triandrte), oppositifolias : 

 capsulse dissepimenta tenuia nunc evanida. Flores in Americanis 

 semper sessiles, trimeri nunc disepali : semina leviter curvata. 



1. E. TRiANDRA, Sclikuhr. Folia oblanceolata vel oblongodanceo- 

 lata, basi sensim attenuata: petala stamina etcarpella stepissime 3 cum 

 sepalis 2: semina fere subsequentis vel tenuiora, minus insculpta. 



2. E, Americana, Arn. Folia obovata obtusissima: flores ssepius 

 dimeri, nunc trimeri : semina cylindracea, curvula, liu, circiter ^ longa, 

 testa in lineis 9-10 multi-(20-30-) clathrata. 



3. E. BRACHYSPERMA, n. sp. Folia oblonga seu ovalia basi atten- 

 uata, nunc sublanceolata : flores plerumque dimeri : semina brevi- 

 oblonga rectiuscula, baud ultra lin. ^ longa, testa in lineis 6-7 grossius 

 1 0-1 2-clathrata. 



§ 2. Elatinella, Seubert. Diplostemones (tetramerce octandrae, 

 rarissime trimerce hexandrce), oppositifolife. 



4. E. Califormca, n. sp. Folia obovata basi longius attenuata, 

 inferiores in petiolum lamina baud longiorem : flores breviter pedunca- 

 lati : semina circinato-incurvata JE. Hjdrojyiperis. 



My attention was recently called to our species of tbis genus by a 

 letter from Mr. James Lloyd, communicating specimens of an Elatine 

 wliich he found growing abundantly in the vicinity of Nantes, France, 

 ■which he wished to have critically compared with our E. Americana, 

 but which has, as he remarked, much narrower leaves and trimerous 

 flowers, except that the sepals are almost always dimerous. If new, 



