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The Garden Magazine, February, 1922 









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The surrounding country near the Laboratory* is desert, and 

 only the restricted surface above 7,000 feet affords conditions 

 suitable for the growth of a forest, principally of Pines, in which 

 are also to be found Oaks, Spruce, Poplar, Walnut, and small 

 Maples. The annual rainfall varies from 30 to 40 inches, coming 

 in winter snows and midsummer rains. The thermometer falls to 

 1 5°F and rises to 85 or go° F in the summer; the period in which 

 growth is possible being nearly five months. 



Now such a characterization would seem to duplicate con- 

 ditions in Michigan, New York, or New England, and when the 

 experiments were begun in 1906, a number of species were 

 brought from these regions and put into the experimental plots 

 on the Santa Catalina mountains about forty miles from the 

 Desert Laboratory. One of the most interesting features of 

 the result was the high percentage of failures. Arisaema, 

 Menispermum, Aletris, Apios, Bicuculla, Salomona, Lobelia, 

 Vitis, Hamamelis, and others failed utterly, although introduced 

 in large numbers and in several seasons. Fragaria virginiana, F. 

 vesca, Hepatica, Podophyllum, and Scrophularia showed sur- 

 vivals, actual vigorous establishment being noted only in the 

 Strawberries and Podophyllum. 



The disappearance of the other introductions could not be 

 attributed to the temperature or to the total rainfall. The 

 air, however, shows a low relative humidity except in cloudy 

 weather, and the soil moisture runs low before the summer rains 

 begin. These conditions, together with the cold nights, are 

 adverse to the survival of many lowland plants. 



HAVING some means of estimating the mountain climate 

 in the terms of the meteorologist and with regard to 

 its effects on well-known plants, we were in a better position to 

 appraise the behavior of plants native to the region when trans- 

 ported eight hundred miles to the California Coast. 



The plots at the Coastal Laboratory, a hundred miles south 

 of San Francisco, are a few hundred yards from the beach. The 

 climate is of the equable type. The thermometer falls to the 

 freezing point for a few hours only each year, and while it does 

 show temperature as high as 90°F, yet the actual exposure at 



*The Desert Laboratory of Carnegie Institution at Tucson, Arizona. 



H 



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T 



THE ARIZONA WALNUT AT 

 THE SEASIDE 

 The larger tree with many branches, 

 at the ieft, was grown from a nut from 

 the mountain top, and the slender tree 

 at the right came from a nut taken 

 from a tree at the base of the moun- 

 tain. Both are 12 years old 



this temperature is so small 

 in comparison with the du- 

 ration of the growing sea- 

 son, which extends over 

 eight or nine months, that 

 the effect is slight. Rain- 

 fall comes in the winter 

 season and spring, begin- 

 ningagain in late fall, so that 

 the soil moisture progres- 

 sively decreases to a mini- 

 mum of 5 or 6 per cent. 

 by August. 



The illumination on the 

 mountain top is intense. 

 Fogs which may hide the 

 sun for two or three weeks 

 occur in the coastal loca- 

 tion. Bringing a plant to- 

 such a place is evidently an 

 experiment widely different 

 from that of moving a plant 

 down a mountain slope in a 

 well-watered region to the 

 plains and valleys below. 

 Eighteen species were taken from the "insular" mountains 

 in Arizona to the California coast in a descent of a vertical mile 

 and a half; of this number fifteen survived. But half of the 

 Eastern species previously taken to the mountain top with a 

 high percentage of failures, survived in this location. 



The plants from the mountain which lived through their de- 

 scent to the shore were: Dugaldea Hoopesii (Owl's-claws), 

 Fragaria vesca (Western Strawberry), Juglans major (Arizona 

 Walnut), Oenothera Hookeri (Hooker's Evening Primrose), 

 Parthenocissus dumetorum var. laciniatum (American Ivy), 

 Potentilla Thurberi (Thurber's Cinquefoil), Quercus hypoleuca, 

 Quercus reticulata (Small Mountain Oaks), Rhamnus ursina 

 (Coffee Berry) Ribes pinetorum (Mountain Gooseberry), Rud- 

 beckia laciniata (Cone-flower), Scrophularia parviflora (Fig- 

 wort), Sedum stelliforme (Stonecrop), Tradescantia scopulorum 

 (Spiderwort), Vitis arizonica (Arizona grape), Solanum Fendleri, 

 (Fendler's Potato). 



The introductions were begun after three years' experience 

 with these species in their mountain habitats, and in all cases 

 the transfer was made at the time when conditions were sup- 

 posedly most favorable. The least possible tillage was used in 

 the plots at the seaside, the purpose being to test the actual 

 chances of survival under conditions most nearly approximating 

 those which might occur without the intervention of man. 

 The soil in both cases contained a large proportion of decom- 

 posed granite, but the substratum is such a complex factor and 

 is so largely a function of the climate that too much must not 

 be made of this feature. 



The plants native to the mountain which failed to survive at 

 the seaside included the New Mexican Locust (Robinia neo- 

 mexicana), the New Mexican Squaw-weed (Senecio neo-mex- 

 icana) and a small Cinquefoil (Potentilla subviscosa), which 

 singularly enough ranged widely on their native mountain 

 slopes, but which could not make the adjustment to the coastal 

 climate. 



In addition to the three years of experience with the mountain 

 plants before actual transfers were begun, two or three visits 

 were made each year to the mountain habitats, while the greater 

 part of the summer was spent at the coastal location, so that the 



