THE 
vs* 
JUL 3 1 797 
New Phytologbt 
Vol. XIX, Nos. 5 & 6. May & June, 1920. 
[Published July 10th, 1920.] 
PHYSIOLOGICAL ANATOMY OF XEROPHYTIC 
SELAGINELLAS. 
By J. C. Th. Uphof, Ph.D. 
[With Text-Figures, I-XIL] 
^TT^HE writer has made an attempt to obtain data on the 
behaviour of xerophytic Selaginellas, by investigations carried 
out in the deserts of Southern Arizona, California, Northern 
Sonora, Mexico, and on bare mountain tracts and rock outcrops in 
eastern and south-eastern Missouri. The laboratory work was 
conducted at the University of Arizona, and at the Herbarium and 
Jodrell Laboratory at the Royal Gardens, Kew. The author is 
much indebted for kind help to Sir David Prain, Director, and 
Dr. Arthur W. Hill, Assistant Director of Kew Gardens, to Dr. 
Otto Stapf, Curator of the Herbarium at Kew, to Mr. L. A. Boodle, 
Curator of the Jodrell Laboratory, to Mr. A. Gepp, Curator of the 
Cryptogamic Herbarium of the British Museum of Natural History, 
South Kensington, and to Mr. W. Emary for preparing the 
manuscript for publication. 
The genus Selaginella consisted in 1887 according to Baker (1) 
of 334 different species, in 1900 ( vide Hieronymus (7) in Englerand 
Prantl, Die Naturlichen Pflanzenfamilien) of 559, and in 1910 (vide 
the present writer’s (26) Die Pjlanzengattungeri) of 580 known 
species. Like the ferns, most species are adapted to moist, shady 
situations; the forests of the tropics and sub-tropics being 
unusually rich in various forms. About 6 per cent of the species, 
however, inhabit dry localities, such as deserts and rocks of the 
Old and New World. 1 found their geographical distribution 
closely associated with that of xerophytic ferns, as has been out¬ 
lined by Christ (3), their main distribution being the semi-arid 
regions of Mexico, the South Western part of the United States 
(especially Texas, New Mexico, Arizona and California), South 
America, Arabia, South Africa, the Mediterranean and the deserts 
