Bd. XCV. Nr. 12. XXV. Jahrgang. 



Botanisches Centralblatt. 



Referirendes Organ 



der 



Association Internationale des Botanistes 



für das Gesammtgebiet der Botanik. 



Herausgegeben unter der Leitung 

 des Präsidenten : des Vice-Präsidenten : des Secretärs : 



Prof. Dr. K. Goebel. Prof. Dr. F. 0. Bower. Dr. J. P. Lotsy. 



und der Redactions-Commissions-Mitglieder : 



Prof. Dr. Ch. Fiahault und Dr. Wm. Trelease. 



von zahlreichen Specialredacteuren in den verschiedenen Ländern. 

 Dr. J. P. LotSy, Chefredacteur 



No. 12. 



Abonnement für das halbe Jahr 14 Mark 

 durch alle Buchhandlungen und Postanstalten. 



1994, 



Alle für die Redaction bestimmten Sendungen sind zu richten an Herrn 

 Dr. J. P. LOTSY, Chefredacteur, Leiden (Holland), Oude Rijn 33 a. 



Coville, F. V. and Mac Dougal, D. T., DesertBotanical 

 Laboratory of the Carnegie Institution, p. 1—58. 

 PI. I— XXIX. fig. (in text) 1—4. Publication No. 6. Car- 

 negie Institution of Washington. Nov. 1903. 



The authors were requested, by the Carnegie Institution, to act as 

 committee of inquiry as to the best location for a desert botanical labo- 

 ratory, a grant for which had been made. The above named contribution 

 constitutes their report. In addition to a description of the trip for the 

 purpose of selecting a site for the laboratory, there is also included an 

 account of the general botanical and climatic features of North Ame- 

 rican deserts. One of the first places visited was the region of the sand 

 dunes of Chihuahua, which are composed of an almost entirely sili- 

 ceous sand. Next the Tu 1 a ros a desert in New Mexico was examined. 

 Here there is a remarkable area of driiting sand composed mainly of 

 gypsum (calcium sulphate). Some interesting formations were noted, 

 among which the most remarkable are, the pillars of sand caused by the 

 binding action of the roots of Rhus trilobata, and specimens of Yucca 

 ra-diosa which had grown up through a dune 30 feet high. 



After this the region near Tuscon, Texas, was visited and here 

 the writers finally decided that the laboratory should be located, since 

 it combined the necessary features of a strictly desert flora and of habi- 

 tability. The actual site for the laboratory (since built) is about two 

 miles from the city of Tuscon, on a spur of T u s c o n mountain. From 

 Tuscon the authors proceeded to the Sonora region of Mexico, as 

 far as Guaymas on the Gulf of California. In the general de- 

 scription of the Vegetation numerous forms are mentioned, among 

 the most striking of which is a cucurbitaceous tendril bearing plant, 

 Ibervillea sonorae, which has an enormously thickened root and stem 

 base, and the tree-like Ipomoea arborescens, which grows from 20 to 30 

 feet high. In Guaymas it was possible to include in one photograph 

 a remarkable mixture of plants, where the Strand flora of mangroves 

 grew in close juxtaposition to species of Cereus. 



Botan. Centralbl. Bd. XCV. 1904 19 



