200 SUMMARY OF CURRENT RESEARCHES RELATING TO 



Relation of Soils to Vegetation.* — B. E. Livingston lias studied the 

 relation of soils to natural vegetation in Roscommon and Crawford 

 Counties, Michigan. Be finds that the main factor in determining the 

 distribution of the forests on the uplands of this region is that of the 

 size of soil particles, the sorting of which dates hack almost entirely to 

 the close of the last Glacial epoch. The size of the particles determines 

 the amount of air and moisture in the soil, and these in turn determine 

 the amount of humus formation and the growth of nitrifying organisms, 

 and perhaps also to some extent the amount of soluble salts in the 

 surface layers. A factor of less importance, because applicable only over 

 small areas, is the nearness of the underground water level to the surface. 

 Broadly speaking, physiography determines the vegetational distribution. 

 The physiographic features are largely those of glacial topography, or 

 traceable directly to these. It is probable that many dry soils have at 

 length become moist enough to support one of the more moisture-loving 

 types of vegetation simply by increase of humus content. The lowlands 

 are covered with a vegetation complex of species such that they can bear 

 excess of water and paucity of oxygen in the soil. From the open 

 meadow and coniferous swamp we pass, with better and better drainage, 

 through the mixed swamp to the hardwood, or the white pine of the 

 uplands. The natural re-forestation of the pine areas with Xorway pine, 

 and partly, at least, with white pine, will probably occur if the fires can 

 be suppressed. 



Asiatic Plants.f — D. Prain has published notes on various Indian 

 and East Asiatic plants. These include a new genus of Araliaceee 

 (Woodburnia) from Burma, described as a striking plant with flowers 

 unusually large for the family ; a new Mum, from Assam, a fine species, 

 which in habit much resembles a Sikkim variety of the common Musa 

 paradisiaca, and several new Convolvulaceae from China and Malaya. 

 The author also gives some critical notes on the Roxburghiaceaj, with a 

 key to the species of Stemona. 



Flora of the Australian Alps.! — J- Stirling has studied the flora 

 of this area with a view to ascertain the origin and distribution of 

 the mixed types of plants now flourishing on the higher altitudes over 

 South-East Australia, and its relation to the tertiary floras of South- 

 East Australia. The author has collected more than 1000 species in 

 the region at elevations between 2000 and 7000 feet, and the present 

 is a preliminary account, with a census of the plants. The general 

 study of the flora shows that climatic conditions have had a dominating 

 influence in the evolution of varietal forms. This is especially noticeable 

 in the genus Eucalyptus. 



The author gives an account of the physical features of the 

 range. All the higher plateaux are distinctly Alpine ; the soil is 

 rich, volcanic, and highly productive. Fine Eucalyptus forests clothe 

 the sub-Alpine levels. The plants comprise 240 genera, with 117* 

 species of Seed-plants ; and 161 genera, with 841 species of Cryptogams. 



* Bot. Gazette, xxxix. (1905) pp. 22-41. 



t Journ. Asiat. Sue. Bengal, lxxiii. (11)04) pp. 14-24 and 39-4G (1 pi.). 



X Trans, and Proc. Bot. Soc. Edinburgh, xxii. (1904) pp. 319-95 (3 pis.). 



