906 



Only 6 species (Salix herbacea, Vacc. mijrtillns, Erica, Calhina, 

 Empetnim and Thymus) are common and imi)ortanl for the phy- 

 siognomy of the vegetation. 



The remaining 255 perennial species ol" the Færoes are herbs. 



2. Biological types in Raunkiær's acceptation. 



At a meeting of the Danish Botanical Sociely in December 1903, 

 Mr. C. Raunkiær gave a lecture on a new phyto-geographical 

 classification of the vascular piants. A short Danish summary of 

 this classification appeared in 1904 (Raunkiær 1904), and an ex- 

 haustive account of the subject was published in 1905 under the 

 title »Types biologiqiies poiir la géographie botanupie« (Raunkiær 

 1905); more recently an enlarged Danish edition has been issued 

 (Raunkiær 1907). The basis for M. Raunkiær's classification is as 

 follows: the structure and form of piants are infiuenccd by and 

 dependent on the climate, more especially the unfavourable season 

 of the year, — winter, period of drought, etc. This relation to the 

 climate becomes an expression in the manner and the degree in 

 which the buds surviving the unfavourable season are protected, 

 If therefore we study the adaptions of the species for surviving the 

 unfavourable season, we will find a scale of adaptations ranging 

 from species the buds of which are not protected at all, because 

 these piants live in countries where there is no unfavourable 

 season, to species the buds of which are highly protected. Raun- 

 kiær has now arranged these different stages of protection into 

 categories — his biological types — and infers that these fur- 

 nish a biological characteristic for the climates of the differcnt coun- 

 tries of the earth. In the w-armer parts of the earth, it will be 

 found that the less protected »types« are more in evidence than in 

 the colder. There is, however, a further great difference if the 

 country has or has not a distinct dry season. In the tropical rain- 

 forest the buds of most of the piants are not protected against any 

 unfavourable season, because there is none; the dominant species 

 there are large trees with evergreen leaves and often with no scales 

 hiding the embryonal leaves: Raunkiær's Mega- and Mesophanero- 

 phytes. But piants of other »types« also occur in the tropical rain- 

 forest. Hence it is not the case that all the species occurring in a 

 given country belong to oue and the same »type«, but only that in 

 a certain climate one or a few of the types are relatively dominant. 



