CORYLUS 



313 



The smallest species is the Gee4n or Mountaik Alder (568) — Aliius 

 crispa (A. vlridis), — which never grows to over 10 feet. It can he surely 

 known hy the winged nuts or seeds, 

 in the cones, nearly J inch wide. 

 The other two American species are : 

 Speckled or Hoary Alder (559) — 

 Alnus inc^na, — with leaves hairy he- 

 neath, at least on the veins; and 

 Smooth Alder (560) — Alnus ru- 

 g6sa, — with leaves green and smooth 

 on both sides. The tallest species and 

 the only one which grows well in dry 

 places is Black Alder (561) — Alnus 

 glutinbsa — of Europe, with gummy 

 twigs, sometimes reaching the height 

 of 70 feet. The fibres given illus- 

 trate the great variety of foliage in 

 the forms of this species. 



[Seeds; twig cuttings ; suckers.] 



C6rylus. The Hazelndts and 

 TiLBEKTS are shrubby plants with -L 

 rounded hard-shelled nuts inclosed 

 more or less in green leaf-like bracts. F'G- 556.— Shrubby Birch. 



The leaves are alternate, simple, straight-veined with notched edges. The 

 three common species can be best separated by means of the difference in 

 the bracts which surround the nuts : in the Beakkd Hazelsot (562) — 

 Corylus rostrJita, — 2 to 6 feet high, the bracts 

 are not very leaf -like and project beyond the 

 nut into a beak ; in the eastern Hazelnut (563) 

 — Corylus aiheric5,na, — 3 to 8 feet high, these 

 bracts form a fringe-like 

 border generally hiding 

 the nut ; the Eukopean 

 Filbert (564) — Cory- 

 lus Avellana — grows 

 much taller, to 15 feet, 

 and never has the bracts 

 fully hiding the nut. 

 Of this last species, 

 which has been culti- 

 vated for centuries, there are many named varieties: aurea, yellow 

 leaves; laciniSita, deeply cut leaves; p^ndula, weeping; etc. The other 



Fig. 557. — Seaside Alder. 



