156 ARTIFICIAL FORMATION OF WOODS. 



the best results were obtained with coverings of llie following 



tliickiiess : — 



redunciUate oak .... 1-50 inclies. 



Beech -75 ., 



Sycamore and silver fir . . . 'GO „ 



Scotch pine and spruce . . . ';jO ,, 



Common alder . . . . "40 „ 



Larch . . . . . '35 ,, 



Ehu -12 „ 



The seed can be covered in various ways, by ploughing 



(in the case of acorns), harrowing, raking, light hoeing, or by 



scattering fine earth over it. Some small seeds, such as that 



of Ficus elastica, need not be covered at all. 



<1. Sproutinfi nf the. Seal. 



During germination the rootlet is first developed, and then 

 the stem ; as soon as the latter breaks through the surface of 

 the soil, the seed is said to sprout. A few European species, 

 such as oak, sweet chestnut and hazel, leave their cotyledons 

 below the surface, but the majorit}' bring them above ground. 



The interval of time between the sowing and sprouting 

 depends on the species, the age of the seed, and the conditions 

 of germination. 



S})ccic>i. — Good seed sown in spring, under average con- 

 ditions, may be expected to sprout after a lapse of time 

 ranging from a week up to two and even three years. The 

 following data may be taken as illustrations : — 



Poplars and willows . . after about 1 — '2 weeks. 



Elm and birch 2 — 3 



Scotch pine, black pine, 



Weymouth pine, and larch ,. ,, 3 — 4 



Spruce, silver fir ,, 3 — 5 



Oak, beech, maple, and alder . .. ,. 4 — (> 



Ash, lime, hornbeam, and Cembran pine generally after 

 one year, yew after one and often two and even three years. 



