28 Twigs 4-8 mm. wide ; leaves rather spiky, spreading on sides of 



twig FALSE or HIBA ARBOR VITAE (THUJOPSIS) 



28 Twigs 4 mm. wide or less ; side leaves scale-like and appressed, 

 not spiky and spreading except on vigorous shoots, imma- 

 ture plants and varieties. (The spiky form is called 

 RETINISPORA or RETINOSPORA, but is not in a dif- 

 ferent genus) 29 



29 Twigs 3-4 mm. wide, sometimes standing up vertically ; side 



scales nearly covering middle ones....ARBOR VITAE (THUJA) 



29 Twigs less than 3.5 mm. wide ; side scales not much larger than 

 middle ones unless leaves have white marks (not triangles) 

 on under surfaces and one of the following conditions pres- 

 ent : a tree trunk which peels in strips, or a gland on upper 

 surface of leaf 

 WHITE CEDAR, FALSE CYPRESS (CHAMAECYPARIS) l^ 



DECIDUOUS TREES 



30 Leaves simple 31 



30 Leaves compound 148 



31 Leaves fan-shaped, almost parallel veined, sometimes cleft in 

 the middle of the outer margin 



MAIDENHAIR-TREE (GINKGO) 



31 Leaves scale-like or very small, sometimes clasping twig 



TAMARISK (TAMARIX) 



31 Leaves needle-like - 32 



31 Leaves normal foliage leaves, netted veined, not like above de- 

 scriptions — 34 



32 Leaves scattered along twig, never in clusters, appearing 



2-ranked BALD CYPRESS (TAXODIUM) ^ 



32 Leaves in clusters on spurs, sometimes also scattered spirally.... 33 



a Leaves Z-1 cm. long, at least 3 mm. wide, long-pointed 



GOLDEN or CHINESE LARCH (PSEUDOLARIX) 



IZ Leaves 1.5-4 cm. long, less than 3 mm. wide, blunt-tipped or 

 short-pointed 



LARCH, TAMARACK, HACKMATACK (LARIX) 



lU 



