328 BRITISH FOREST TREES 



cross, the number of species is constantly on the increase ; 

 thus pentandra and fmgilis yield S. cuspidata, purpurea 

 and viminalis yield S. rubra, &c. In the formation of new 

 willow plantations the species should be segregated as much 

 as possible in the various beds, according as the concrete 

 factors of soil and situation promise the best returns, for the 

 different osiers have distinct preferences in this matter, as 

 well as in other sylvicultural respects. From this point of 

 view Esslinger x has classified them into the following main 

 groups : 



1. Laurel-osier group (S. triandra, amygdalina, hippophaefolia, c.), 



demanding a light, fresh or moist soil, and yielding withes of 

 first-rate quality for technical purposes. These species suffer 

 comparatively little from insect enemies. 



2. Osier group (S. viminalis, &c. ), demanding a light, moist soil, 



and best capable of standing wetness of soil ; yield a very good 

 outturn of useful material for basket-making and wicker-work, 

 but much liable to attacks from insects. These are the principal 

 species for cultivation on sandy soils. 



3. Purple osiers (S. purpurea, rubra, &c.), content with a dry soil, 



and yielding numerous, but thin, withes, suited for all technical 

 purposes ; not much attacked by insects or rats. 



4. Caspic or prunose osiers (S. acutifolia = prunosa caspica, 



daphnoides, &c. ), whose young shoots are covered with a bluish 

 soft bloom, thriving on dry soil, and yielding clean but not 

 numerous shoots of ten feet in length, only suitable for coarser 

 technical purposes. These species probably deserve most atten- 

 tion for railway cuttings and similar localities. 



Osier-beds are usually formed either naturally or artifi- 

 cially in the low-lying localities adjacent to lakes, rivers, and 

 large streams, as the first condition for the success of most 

 of the species is either a plentiful supply of soil-moisture in 

 motion, or else considerable fertility of soil. The holts 

 of spontaneous formation are as a rule just above the level 

 of the water, so that, whenever floods take place, the silt is 



1 Transactions of the Palatine Forstverein in Kandel, 1882, p. 54. 



