66 Miibltriiberi^na, \'olunie 7 



Other species. This species was found in arroyos in Sonora by 

 Thurber, making a "plant 4-6 feet hig-h." Similarly it was 

 found on the bottom of White river, a large sand wash in south- 

 eastern Arizona, altitude about 5000 feet, where it grew abund- 

 antly in places, two to three feet high. Here it was collected 

 July II, 1907, no. 202y. It would be interesting to know 

 whether it is always or usually a riparian plant. 



C. LAXA Gray, Bot. ]\lex. Bound. 119. 1859. 

 The type of this species was collected by Charles Wright on 

 hillsides near the Mexican village of Santa Cruz, just over the 

 boundary in northeastern Sonora. It appears to be distributed 

 from Arizona to Sonora and Durango. Collected in the upper 

 Sonoran zone in the Rincon mountains, Arizona, at an elevation 

 of 5800 feet, September 13, 1909, no. Jjj/, and again in the 

 same zone of the same mountains at 6500 feet, October 20, 1909, 

 no. 3492. At the first station it was growing in clumps under 

 evergreen oak trees in leaf mold on top of a ridge, giving a hand- 

 some mass effect. At the second station it occupied a similar 

 habitat of comparative dryness among chapparal on a sunny 

 southeast slope. First collected in the same zone (6000 feet) in 

 the Chiricahua mountains, on top of a ridge near Wilgus ranch, 

 September 2, 1908, no. 21 j2. On x\ugust 18, 1908, what is 

 probably this species was collected in the Upper Sonoran region 

 of the Sierrita mountains, no. 2j63 in open ground, no. 2366 

 (habitat not stated), and no. 2j6j\\\ a dry gulch. No. ^5'(5f was 

 met at Warsaw M.ills, in the Pajarito mountain-;, which was one 

 of Dr. E. A. Mearns' collecting stations. Here it occurred in a 

 somewhat protected place in a gulch, as might be expected, for 

 the elevation is only about 4000 feet That the species has a 

 very extended flowering season is indicated 1)\' the fact that it 

 was here gathered in bloom on April 21, 1909. Even two days 

 previously it was found on an open, dry bank, but in the bot- 

 tom of the deep and tortuous Canyon de los .\lisi)s on the bound- 

 ary, altitude about 3500 feet, no. 2641 . The.se collections indi- 

 cate that C. laxa is a species quite generalh- distributed at mid- 

 dle altitudes of the boundarv reeiou. 



