654 JOURNAL OF THE ROYAL HORTICULTURAL SOCIETY. 



New Mexico lies under the 35th parallel and at altitudes of from 5000 

 to 11,000 feet. The climate is arid ; rainfall at Albuquerque 7.43 inches, 

 but with much heavier precipitation in the mountains. 



Along the Eio Grande, where the water-table is never far from 

 the surface, there occur associations of cotton-wood [Populus Wis- 

 lizenii) and Juncus Houttuynia (J. halticus), the latter sometimes being 

 overgrown and occupied by the former. 



The recent valley of the Eio Grande is cut out of an ancient 

 river terrace or " mesa," which extends 9 to 10 miles eastwards to the 

 mountains and is apparently 100 to 300 feet above the present valley. 

 This mesa was originally a grassland, and is so still when not 

 over-grazed, but is now often a Gutierrezia (Chrysothamnus) associa- 

 tion with Opuntia, Yucca, many annuals (summer and winter), and 

 perennials, with underground stores of moisture. The last blossom 

 after the rains. In very dry years Gutierrezia blooms only in the 

 mountains or along trails where the dust of the trail conserves the 

 moisture. 



Many interesting xerophytic associations are found on the dry 

 dissected edges of the mesa or in the side valleys, which are some- 

 times sandy or alkaline. Towards or on the mountains, at about the 

 lower limit of the winter snow, a juniper {Juniperus monosperma) and 

 pinon {Finns edulis) formation replace the Gutierrezia. 



Next comes the transition zone of yellow pine (P. ponderosa) 

 which marks a sharp and complete change of flora and is more 

 closely allied to that of Ohio than to that of the mesa only a mile 

 away. It coincides with the region of deep winter snow, and occa- 

 sionally gives place to mountain meadows. The Douglas spruce 

 formation — a dense forest — covers slopes facing north at altitudes 

 above 8000 feet {Pseudotsuga taxifolia, Berberis, Galium, Monarda, 

 Oxalis, Corydalis, Clematis, Aquilegia, Stellaria). This is confined 

 to the most mesophytic places. Engelmann's spruce is found on 

 the highest and most exposed parts of North Mountain. The summits 

 are covered with chaparral (oak scrub), with yellow pine at lower 

 and Ahies concolor at higher levels. 



The influence of moisture is very distinct in this arid district, 

 Fallugia paradoxa occurs in the side valleys of the mesa and also 

 on steep south-westerly slopes over 9000 feet on the mountains — that 

 is, in the least xerophytic part of the valley and most xerophytic 

 habitat of the hills.— G. F. S. E. 



New Plants of the Rocky Mountains. By Aven Nelson {Bot. 

 Gaz. vol. liv. pp. 136-151; Aug. 1912). — The author describes new 

 species of Sisyrinchium, Eriogonum (2 spp.). Polygonum, Loeflin- 

 gia, Parrya, Taraxia, Cicuta, Cynomarathrum, Phacelia, Gilia, Cryp- 

 tantha, Pentstemon, Castilleja, Lesquerella, Astmgalus, and Mertensia 



G. F. S. E. 



Nitrification, Influence of Moisture up:n. By J. W. Paterson 



and P. B. Scott {Jour. Dep. Agr., Victoria, x. p. 275; May 19] 2) — 



