SPRI^STG VEGETATTOJs^ IX THE DESEBT. G3 



SPRIXG FLOWEES OF THE AEIZOXA DESEET. 



Professor V. M. Spalding. 



February is the early spring month in Southern Arizona, 

 and flowers begin to bhjom in great numbers before the opening 

 days of March. The present year has been fav(jrable, as far 

 as physical conditions are concerned. There was a good deal 

 of rain early in the winter, and for weeks preceding the present 

 date, February 14, 1007, the temperature has been rather high 

 for the time of year. As might bo expected, therefore, Tum- 

 amoe hill, on which the Desert Botanical Laboratory is situated, 

 has for a week or more ])resented a great profusion of spring 

 flowers ; many of them, it is true, small and inconspicuous, but 

 others, such as the anemone, beard-tongue and California popp}^, 

 fully as showy as their congeners elsewhere. 



As many as thirty-two different species have been observed 

 in flower here this month, and this number would be consider- 

 ably increased if a wider area were taken. Some of them, nota- 

 bly certain species of Cruciferae and Boraginaceae are already 

 forming fruits in the middle of February. Fourteen out of the 

 thirty-two listed are annuals, and are all characterized bv the 

 great rapidity with which they push out of the ground in earliest 

 spring, unfold their flowers, and mature their fraits, as if fear- 

 ful that the least delay might result in their death by drying up 

 before their seeds are sown. Indeed, if winter rains have failed, 

 as sometimes happens, they take no chances, luit stay in the 

 ground until another year. Thus the effects of a dry winter 

 are visibly and painfully apparent in February and March in 

 the endless stretches of brown, dry mesa, while winter rains are 

 quite as surely and far more cheerfully attested l)y the millions 

 of bright green winter annuals that cover the desert like grass. 



It is often remarked that these winter annimls are not true 

 children of the desert, that they exhiljit no xerophytic structures, 

 and have merely slipped in amongst the perennials which are tli,^ 

 genuine xerophytes of the region ; but it would be hard to affirm 

 that those latter hold their places and reproduce their genera- 



