348 BOTANICAL GAZETTE [november 



the exposed mountain slopes. The height of the trees and density 

 of the foUage is not such as to produce more than a riioderate amount 

 of shadcj so that the under layer is not composed exclusively of dense 

 shade-loving species, while the amount of moisture retained by the 

 soil is sufficient to support an abundant growth of plants. The under 

 layer is mixed and for the most part open. Some of the more frequent 

 members are Artemisia iridentala, Arctostaphylos uva-ursiy Achillea 

 lanulosa, Poa trifloray Antennaria parvifoliay Poa pratensiSy Aquilegia 

 coeruleay and Castilleja acuminata. 



A series of three observations of the physical characters of the 

 habitat of this formation, taken at a point at 2490^ altitude approxi- 

 mately, in a little hollow where the general slope was southwest and 

 very gradual, gave the following results,^ == the observations being made 

 July 5, 6:10 P.M.; 25, 4:05 P.M.; August 28, 5:45 P-M. 



Temperatures 



— 22.5«'" —II. 25*^^ • ©c™ 7.5*°* 9^"^, 



Minima..... i4?5* 12° ii?2 11° ii-5 



Maxima X4?5 * 16^ 19° t ^7 • 5 ^8?2S 



Relative humidity 



Minima. .- . 68 per cent. 55 per cent. 



Maxima 89 per cent. 71 per cent. 



Water content 



Observations 1 1 ,25^**^ 22 . 5 — 1 1 . 25"^°* 



July 5 17.3 percent. 



July 25 21. 1 per cent. 7.9 per cent. 



Aug. 28 20 .9 per cent. 9 . i per cent. 



Light value 

 August 27, 10 A. M =5 : 90 



* One observation only, August 28. 



t Four observations, this recorded on July 14. 



Clements,'^ recognizes the following forest formations in the 

 Pike's Peak region of Colorado: Pinus edulis-Juniperus (mono- 

 spcrma); Pinus ponderosa-flexilis; Populus tremuloides ; Picea 

 Engelmanni and Parryana-Pseudotsuga (mucronata) ; Picea Engel- 

 manni-Pinus (aristata). The first of these is not represented in 

 Boulder County. My reasons for recognizing the Pinus scopulorum, 



" See also the results obtained at Station A on September 20, 

 13 Clemexts, F. K, Formation and succession herbaria. Univ. Nebr. Studies 

 4:329-355- 



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