224 ECOLOGY, PLANT GEOGRAPHY [Bot. Absts., Vol. VI, 



of lakes, some morainal and some rock-basin in type, is described and discussed. Lists of 

 species are presented, with soil-moisture index of each; and the various associations, with their 

 successional relations and seasonal aspects, are described. Definite circum-areas are often 

 developed. The succession leads from aquatic plants (which are few) through a well-devel- 

 oped moor (chiefly Car ex), a heath association (chiefly Kahnia and Gaultheria), and a 

 meadow association (chiefly Erigeron, Castilleja, Ligusticum., Pedicularis and Vaccinium) 

 to the climax association of Engelmann spruce forest. — E. W. Sinnott. 



1512. Rand, R. F. Wayfaring notes from Great Namaqualand [Southwest Africa]. Jour. 

 Botany 58: 53-55. 1920. — The author visited this region in October, 1919. A brief account 

 of the vegetation is given. It is mainly xerophytic. Patches of desolate country are occu- 

 pied by leafless Euphorbias, and species of Aloe are frequent. As most of the country is a 

 stony, sandy desert, the vegetation is mainly confined to the river beds, where trees of consid- 

 erable size, principally Acacias, may be found. Gomphocarpus fruticosus, an asclepiad, and 

 a pestiferous weed in many parts of Africa, occurs here in profusion. The nature of the 

 sand-rivers is described in some detail. The plants are the despair of collectors, as they are 

 so difficult to press. They are, however, very beautiful when living and in flower. — K. M. 

 Wiegand. 



1513. Watson, W. Habitats of Hypericum humifusum. Jour. Botany 57: 353-354. 

 1919. — The author questions H. S. Thompson's statement in Jour. Botany that this plant is 

 calciphile. He is inclined to agree with other botanists that it is calciphobe. May not its 

 occurrence in limy regions be due to its shallow-rooted habit, the superficial layer of soil being 

 acid? In one corn field, however, the author found the plant associated with calciphiles in 

 such a way as to make an explanation difficult. — K. M. Wiegand. 



FLORISTICS 



1514. Bertsch, Karl. Warmepflanzen im oberen Donautal [Germany]. [Warm tem- 

 perature plants in the upper Danube Valley.] Bot. Jahrb. 55 (Beiheft) : 313-349. 6 fig. 1919. 

 In this study the more typically alpine plants were excluded, as well as those occurring 

 sporadically. Rare plants in stone quarries and gravel beds have often come from a distance 

 and should be excluded. As a rule no isolated plants are endemic. All introduced plants 

 were excluded from the study as far as possible; this was difficult, as local introduction of 

 native plants is common. Plants of general distribution were also excluded. There was left 

 a small group of plants which over a circumscribed area inhabited all available places. These 

 island-like areas were the only infallible assurance of truly indigenous conditions. About 

 sixteen species were finally included. Warm temperature plants would not be expected in so 

 cold a climate, but is to be explained by the insolation. Heath and sand plain plants of warm 

 countries are here restricted to rocks which are warmed by the sun or in some cases by 

 chemical action. Most warm temperature plants live near the tops of the cliffs, where they 

 avoid the frosts of the lowlands. The true heat conditions are shown by the warm-climate 

 types of fruit trees that can be grown there. On the south side the warm temperature plants 

 extend nearly to the bottom of the valley. They cover about 1/2000 part of the Alb Moun- 

 tain. The comparative altitude of these plants here and in South Bavaria is studied, the 

 lower limit especially being of great interest. The individual stations for our plants in the 

 southwest, central and northeast slopes of the Alb are in the ratio of 87: 9: 1, which is remark- 

 able as the temperature is higher in the northeast. The hypothesis that the presence of the 

 warm temperature plants on the Alb is due to a post-glacial steppe period, is not supported 

 by the conditions on the southwest slope. These plants were there before the glacial period, 

 and by a study of the snow line it is shown that the southwest slope was free from ice at 

 that time, while the northeast slope probably was not. Warm temperature plants now 

 live near the glacier and obviously could have so lived during the glacial period. It is inter- 

 esting to note that alpine plants are frequently found in the valley, while the warm tem- 

 perature plants are only on the edge. — K. M. Wiegand. 



