CORYLUS 



313 



The smallest species is the Greex or Mountain Aldkr (558) — Alnus 

 crispa (A. viridis), — which never grows to over 10 feet. It can be sui'ely 

 known by the winged nuts or seeds, 

 in the cones, nearly i inch wide. 

 The other two American species are : 

 Speckled or Hoary Alder (559) — 

 Alnus incana, — with leaves hairy be- 

 neath, at least on the veins j and 

 Smooth Alder (5G0) — Alnus ni- 

 gosa, — 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 

 glutinosa — of Europe, with gummy 

 twigs, sometimes reaching the height 

 of 70 feet. The figures given illus- 

 trate the great variety of foliage in 

 the forms of this species. 



[Seeds; twig cuttings ; suckers.] 



Fig. 556. — Shrubby Birch. 



C6rylus. The Hazelnuts and 

 Filberts are shrubby plants with 

 rounded hard-shelled nuts inclosed 

 more or less in green leaf-like bracts. 

 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 Beaked Hazelnut (502) — 

 Corylus rostr^ta, — 2 to 6 feet high, the bracts 

 are not very leaf-like and project beyond the 

 nut into a beak ; in the eastern Hazelnut (503) 

 — Corylus americana, — 3 to 8 feet high, these 

 bracts form a fringe-like 

 border generally hiding 

 the nut ; the European 

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



Fig. 557. — Seaside Alder. 



