154 JOURNAL OF THE ROYAL HORTICULTURAL SOCIETY. 



of Quebec and the shores of Lake Champlain down the Connecticut River and 

 along the Atlantic coast south to northern Florida ; and westward, except in the 

 higher altitudes of the Appalachians, through the Mississippi Valley to the foot- 

 hills of the Rocky Mountains in New Mexico ; and northward into southern 

 Alberta. East of the Appalachians it is very scattering and rare. It follows up 

 the tributaries of the Mississippi River into the Great Plains region, where it is 

 found at altitudes as high as 9,000 feet, but is confined to the river banks. 



One serious objection to cottonwood is its rapid decay when exposed to the 

 weather or when in contact with the soil. To make the wood more durable, 

 preservative treatment will in many cases be necessary. Because of its open, 

 porous texture, cottonwood takes preservatives readily, the treatment requiring 

 comparatively small expense. 



In the manufacture of shipping cases for food products cottonwood is used 

 in large quantities. When properly seasoned it imparts little, if any, taste or odour 

 to the contained product. For this reason also it is in demand for candy pails 

 and the like. Its toughness and lightness give cottonwood additional fitness for 

 boxes and crates. Experiments by the Forest Service to determine the com- 

 parative strength of packing boxes of various woods demonstrated beyond 

 question that, when taken weight for weight, the cottonwood box outclasses in 

 strength similar containers of practically all other species extensively used — 

 such as white pine, yellow pine, spruce, hemlock, and red gum. Bulk for bulk, 

 cottonwood is surpassed only by red gum. — A. D. W. 



Corn (Zea Mays), Cob Rot of. By E. G. Arzberger (U.S.A. Agr. Stn.. 

 Ohio, Bull. 265, Nov. 191 3, pp. 69-82). — This disease is caused by the fungus 

 Coniosporium Gecevi, Bubak. From a series of exhaustive inoculations on 

 growing corn plants, it appears that this fungus is an obligate saprophyte and 

 is only of economic importance in that it destroys the stored cobs ; apparently 

 it does not attack the growing plants. Its effects on the grains are small compared 

 with those of Fusarium, Diplodia, and other fungi. — A. B. 



Crataegus pubescens, forma stipulacea (Bot. Mag. tab. 8589). — Mexico. Nat. 

 Ord. Rosaceae, tribe Pomeae. Tree, 15-35 f eet high, sometimes with spines 

 i£ inch long. Leaves ovate-lanceolate, serrated, 5 inches long. Corymbs, 

 6-15-flowered, 2 inches across. Flowers white, 1 inch across. Fruits globose, 

 nearly 1 inch across, yellow, with purple spots. — G. H. 



Cyrtosperma Johnstoni (Bot. Mag. tab. 8567). — Solomon Islands. Nat. Ord. 

 Aroideae, tribe Orontieae. Herb, over 3 feet high. Leaves, triangular-sagittate. 

 Petioles, to 3! feet long, armed with short hooks. Blade dull purple below. 

 Spathe erect, 6 inches long, margins incurved, outside dark violet, inside dull 

 whitish-green, at the base rosy-purple. — G. H. 



Cytisus pallidus (Bot. Mag. tab. 8578). — Nat. Ord. Leguminosae, tribe Genisteae. 

 Shrub, 4-10 feet high. Leaves trifoliate. Flowers in 10-flowered cymes, 1 inch 

 from tip of standard to keel yellow. — G. H. 



Distribution of Plants, The Role of Winter Temperatures in Determining. By 



Forrest Shreve (Amer. Jour. Bot. vol. i. April 1914, pp. 194-202 ; 1 fig.). — 

 The control of plant distribution by the temperature factor is one of the 

 important and most difficult tasks in physiological plant geography. The work 

 of Willdenow, Humboldt, and others in delimiting the great temperature zones 

 of the earth in relation to flora must be mentioned. The dictum that the 

 character of the flora is controlled by temperature, that of its vegetation by 

 moisture, originated from the investigations of these observers. 



In considering the influence of the phases of the temperature factor two well- 

 marked groups may be indicated. One deals with those phases which concern 

 the length of the season in which growth and other activities are possible ; with 

 the curve of temperature conditions within this season, and the possible effect of 

 the highest portions of the seasonal curve as deterrent to the activities of plants. 

 The second deals with those which have to do with the length of the season during 

 which low temperatures may exert a deterrent or fatal effect upon physiological 

 activities, and with the duration and intensity of the critical periods in this 

 season. 



One of the most widely used schemes in the formulation of temperature data, 

 so as to give them general applicability in biogeography, is the system of life 

 zones proposed by Merriam. These are based on the isothermal lines which 

 indicate the totalled degrees of temperature for the growing season. This system, 



