KOTES A>1) NEWS. 47 



AVhat may be called the vegetation potential of the desert is 

 hy no means a low one. One of the conspicnons features of such 

 regions, as is constantly exem])lified in the photographs seen in 

 every magazine, is the isolation of individual plants, and the im- 

 pression one invariably receives by this means gives one no idea 

 at all of the immense ])(issil)ilities for ])lant production. 



The first soaking I'ain of the winter fell in the desert about 

 Tucson, Arizona, early in December. This was the o])portunity 

 for the Avinter annuals to germinate, and this they did in a few 

 days at such rate and sncli nnmbers that in many places the 

 gronnd became a carpet of living green. Taking a rough aver- 

 age, one Avould say that fully one-third of the gi'ound was cov- 

 ered thickly enough by seedlings to be called f\dly occupied, and 

 a half of this was distinctly ci-owded. A count of seedlings, for 

 the greater ])art of a species of borage, showed that there were 

 150 ])lantlets to the square inch. The crowding of seedlings is 

 especially noticeable beneatli the shade of shrubs and small trees, 

 a condition due in ])art to the greater conservation of moisture in 

 the upper layer of soil. This acc(uiuts for the observed fact that 

 giant cacti are so often to be found growing in close association 

 with perennials, which aiforded to their scccllings the most favor- 

 able opportunity f(U- germination. As many as a half dozen 

 giant cacti have been seen to liave started in the shade of one 

 ]»:il<» verde. F. E. LI. 



Scarcely inferior to the common garden nasturtium which 

 has become almost as much of a classic in the botanical as the 

 frog in the zoological laboi-atory, is the common round-leaved 

 mallow, MdJra roiiindifohd . in ])oint of exact and ])i'onipt re- 

 sponse to light. In ])l:ic('s wlicrc this plant is ])lentiful the seed- 

 lings may completely carpet the ground, when the uniformity of 

 leaf position with reference to the impinging light is quite re- 

 markable. The round leaf-blades become placed at right angles 

 to the rays of light as the first light dawns, and follow the sun all 

 the day. The plant is so sensitive that even on cloudy days there 

 is very little lapse from the uniformity of ]iositious noted on 



