398 standley: genus arthrocnemum 



Searlesite is rather soft and is readily fusible. It is soluble in 

 hydrochloric acid with gelatinization and appreciably soluble in 

 water. The optical properties are : 



<x = 1.520 2 E very large 



7 = 1.528 Maxjmum extinction angle large 



After correction for insoluble minerals and for calcite the 

 chemical analysis corresponds approximately to Na20,B203. 

 4Si02.2H20. 



BOTANY. — The genus Arthrocnemum in North America. Paul 

 C. Standley, National Museum.^ 



Arthrocnemum is one of the smaller genera of the Chenopodi- 

 aceae, similar in general appearance to Salicornia, but distin- 

 guished by its glabrous seeds, with rather copious endosperm, and 

 by having distinct perianths, which are not immersed in the joints 

 <of the flowering spikes but project from them rather conspicu- 

 ously. In Salicornia the seeds are without endosperm and are 

 covered with numerous short hairs, while the flowers are coalescent 

 and immersed in the joints. 



About eight species of Arthrocnemum are known, all natives of 

 the coasts of the warmer parts of Europe, Asia, Africa, and Aus- 

 tralia. No true representative of the genus has ever been reported 

 as such from North America, although Moquin^ referred Salicornia 

 amhigua Michx. to it with doubt. That species, however, is a 

 true Salicornia. 



In 1898 Mr. S. B. Parish described a new Sahcornia from 

 southern California. His description alone would exclude the 

 plant from the genus, for he describes the seed as "smooth." 

 This character, however, would not seem remarkable to one who 

 had studied Sereno Watson's treatment of Salicornia,* for that wri- 

 ter says, under S. amhigua, "*S. fruticosa of the Old World difi"ers 

 in being erect, stouter and more branched, the seed larger and 

 smooth." The European plant to which Watson referred is 



1 Published by permission of the Secretary of the Smithsonian Institution. 



2 Chenop. Enum. 112. 1840. 

 ■^Proc. Am. Acad. 9: 123-125. 1874. 



