236 cook: glaucothea, a new genus of palms 



the free sulphur and the sulphur remaining after the extraction, 

 reporting the sum of the two quantities as the total sulphur. 

 This procedure eliminates the troublesome effect of the free 

 sulphur upon the determination of the total sulphur. 



BOTANY .^r-Glaucothea, a new genus of palms froin Lower Cali- 

 fornia. O. F. Cook, Bureau of Plant Industry. 



The type of the new genus is Glaucothea armata (S. Wats.),' 

 commonly known in cultivation as the "blue palm," on account 

 of its extremely glaucous foliage. The peculiar color is due 

 to the presence of an unusually thick coating of wax, and may 

 be considered as an adaptive specialization to desert condi- 

 tions. Glaucothea is known in a wild state only from the 

 interior of the northern part of Lower California, about sixty 

 miles below the international boundary. It is the nearest neigh- 

 bor of Washingtonia filifera, the only native palm of California, 

 found in the canyons along the eastern base of the San Jacinto 

 Mountains, in the Salton Basin. 



The new genus is separated from Erythea, whose type is 

 Erythea edulis (Wendl.) S. Wats., a native of Guadelupe Island, 

 off the coast of Lower California. The difference in habitat 

 appears significant when Erythea and Glaucothea are observed in 

 cultivation. Erythea, being a maritime palm, is entirely at home 

 in the cool climate of the Coast Belt of California, flowering and 

 fruiting with great regularity after the proper age has been 

 reached. Glaucothea makes rather slow growth in the Coast 

 Belt, seldom produces flowers, and does not fruit, probably for 

 lack of sufficient heat. Though planted in large numbers in 

 California, the supply of seed is still limited and precarious, 

 being obtained only from the wild palms in the canyons of Lower 

 California. But there is no apparent reason why seed should 

 not be produced eventually by the palms that have been planted 

 in recent years in the drier and warmer interior districts of 

 southern California and Arizona, as at Riverside and Phoenix. 



^ Brahea (?) armata S. Wats. Proc. Am. Acad. 11: 146. 1876. 

 Erythea armata S. Wats. Bot. Calif. 2: 212. 1880. 



