ran(;k kfki). , 51 



eouilMoik piowt'etls. s»'V('i:il 111 uliiili ;iii' closi^Iy related li> tlie laiiili's- 

 (limrtiMs. 



Without doubt the >iiltl)iislu's t'ui-iiish the l;iri;-('st aiiiouut ol IVihI in 

 this natural order and are al)UiKlantly distributed in many situations. 

 s(5nie upon alkaline soil and some upon land with hut little or no salt 

 content. In the southern part of Arizona shad scale {Ati'ijtlr.r cd/h's- 

 cens), ,1. polycarpn^ A. Iintifonnls^ and .1. lineai'h ai'e the most 

 abundant of the shrubby species. These are all known to the Mexi- 

 cans as chamiso. The tirst is not so prominently a salt-lovin<»* plant as 

 the others, although it often occur;:; upon somewhat alkaline soils. In 

 tlu> I'ucson reirion all but the third of these occur al>undantlv and are 

 invariably omzed." Shad scale occurs in the valleys throuehout the 

 Territory, l)ut the other three mentioned above are of most importance 

 in the alkaline \ all(\vs noi'th and west of the Tucson rejj;"ion. They art' 

 especially abundant in the valleys of the (lila and Salt rivers and their 

 tributaries. Afrlphx Jentifnrin'ix \> the most rapidly g^rowino- species 

 of this oenus with which the writer is familiar. Its remarkable devel- 

 opment is well illustrated by observations made in the vicinity of 

 Tempe in 1 !♦<>(». where plants which had sprun^- np on newly sulnlued 

 land aftei' the i<'ino\ al of the tirst cr'v)p of wliejit were r»i feet hioh by 

 the ist of I)eceml)er. This «>rowth had l)een made between the month 

 of flune ajul that date.'' Near Tempe and Phoenix it does not appear to 

 be orazed wvs nmch. Init u[)on the ranji'es alonj^- the (rila River it is 

 not unconmion to see canes one-fourth of an inch in diameter j'^razed 

 oH'. Haxing' about the same ranj^c as the abov*- are two atunial spe- 

 cies, Atrl'ph'X eleganx^ throwing almost exclusively u[)oii nonalkaline 

 soil, and the salt-lovinj^" species. A. lu'drUox'i. Both of these are 

 grazed when feed is scarce. During the past season they were quite 

 closely cropped along the Santa Cruz Kivei" south of Tucson. Atri- 

 j)h.v ('le(/ini.s is a very interesting species in many ways on account of its 

 ha})it of maturing seed at the close of the winter rainy season and 

 again in midsummer. It therefore, although an annual, lives through 

 the hot dry weather of early summer in the vegetative condition. It 

 should be noted that there are some slight differences between the 

 spring and summer forms, and the collections of the writer, although 

 extensive, fail to show one of the common autunmal fruit forms at all 

 in the spring. 



The valley of the Little Colorado is especially noted for its abun- 

 dance of saltbushes. some of which do not grow elsewhere in the 

 Territory, so far as knowMi. The saltbush flora of this region resem- 

 bles that of the valley of the Rio Grande in many respects. Here that 

 most valuable species, the spin}" saltbush {Atrlplex confertifolia)^ so 



«See Bui. 2.5, Division of Agrostology, U. S. Department of Agriculture, 1891, 

 PI. XXVI. 



''See PI. IV, fig. 1. ~ 



