20 The Plant World. 



tween the winter season and the warm dry spring, however, is 

 of too short duration for these plants to be grown successfully. 

 Both have been tried repeatedly, and invariably with failure. 

 Cf 200 tulip bulbs planted by the writer on two occasions only 

 a few ever flowered, and none made good grow^th the second 

 year. When planted on the north side of a building or under 

 lattice, much better results obtain both as to growth and flow- 

 ering; even here, however, their growth was far from satisfactory. 



Neither horse radish nor rhubarb will grow for any length of 

 time in the hottest parts of Arizona, while in its cooler sections 

 the former at least is quite at home, under irrigation. The 

 Chinese gardeners about Tucson grow a small amount of rhubarb 

 in their gardens from two-year-old plants which are then allowed 

 to die, but it must be said the leaf-stalks are very slender and 

 the results are altogether unsatisfactory. 



Among plants grown on a more extensive scale may be men- 

 tioned alfalfa and corn. The former is notably a resistant plant 

 and by far our most important cultivated crop. With moderate 

 to heavy irrigation it makes phenomenal growths, being cut six 

 or more times each year. It is stated on good authority that in 

 the Salt River Valley adjacent to Phoenix, Arizona, its growth 

 is noticeably lessened during the hottest summer weather, al- 

 though the plants suffer no permanent injury therefrom. In 

 the upper Gila Valley in Arizona, where the maximum summer 

 temperatures are several degrees lower, this condition does not 

 obtain. As concerns com, a plant which makes its fastest 

 growth in the com states during the hottest summer weather, 

 it yields only moderately with us when planted late enough in 

 the season to make the bulk of its growth during the summer 

 rainv period, July to September inclusive. A small plat of com 

 imder the writer's observation planted in April 1907, failed at 

 best to set more than a few dozen grains on any of the cobs. The 

 plants were irrigated and cultivated twice each week during the 

 hottest weather, nevertheless, in June the leaves wilted badly, 

 "fired " at the tips, and growth ceased. This condition obtained 

 even when the soil was saturated with water, and only by 

 virtue of the greatly lessened transpiration during the night 

 when the equilibrium was restored, were the plants able to live 

 at all. 



