IDENTIFICATION OF TREES. 195 



KEY TO GENERA AND SPECIES 



1. Leaves persistent and green throughout winter (Evergreens) ...2 



1. Leaves not persistent and green throughout winter (dead leaves 

 often persistent in the Oaks and Beeches) . 11 



2. Leaves broad, prominently spiny-margined. Holly (Ilex opaca) p.396 



2. Leaves narrow, often minute and scale-like; Conifers (i.e. cone- 

 bearing trees) 3 



3. Leaves, except scale-leaves, needle-shaped, in definite, generally 

 sheathed clusters on the sides of the branches Pine (Pinus) 85 



3. Leaves, not in definite clusters 4 



4. Leaves opposite or in 3's, therefore 2 or 3 at a node 5 



4. Leaves alternate, scattered, therefore only 1 at a node 8 



5. Leaves whorled in 3's, all alike, whitened above and green below, 

 awl-shaped, sharp-pointed and spreading; fruit bluish, berry-like; 

 a shrub or low tree. (See also juvenile condition of Red Cedar) . . 

 Common Juniper (Juniperus communis) p.244 



5. Leaves opposite in 4 ranks, minute, scale-like, closely overlapping 6 



6. Young twigs prominently flattened and forming a flat, 2-ranked, 

 fan-shaped spray often mistaken for the true leaves which are 

 minute and of two shapes, those on edges of twig being narrower, 

 those on flat sides being broader and more abruptly pointed with 

 each leaf generally showing a conspicuous raised glandular dot; 



fruit a thin-scaled, oblong, woody cone 



Arbor Vitae (Thuja occidentalisj p.242 



6. Young twigs not prominently flattened; fruit spherical 7 



7. Spray somewhat fan-shaped; young twigs not prominently 4-angled; 

 leaves all alike in shape, some of them with prominent raised 



glandular dot on back; fruit a spherical woody cone 



Coast AVliite Cedar (Chamaecyparis thyoides) p.240 



7. Spray not fan-shaped; young twigs with typical leaves are prom- 

 inently 4-angled; leaves without conspicuous glandular dots, of two 

 kinds; (a) the juvenile form — awl-shaped, spiny-pointed and 

 spreading, in 2's or 3's at a node and resembling leaves of Common 

 Juniper, the usual leaf form on young trees but generally to be 

 found on some parts of older trees; (b) the typical form — smaller, 



scale-like and closely appressed; fruit bluish, berry-like 



Red Cedar (Juniperus vir giniana) p.246 



8. Leaves distinctly flattened 9 



8. Leaves not distinctly flattened, needle-shaped, 4-angled, sessile on 

 projections of the bark Spruce (PiceaJ 91 



9. Leaf about 1 cm. long with definite leaf-stalk, leaving prominently 

 projecting scar when detached. Hemlock (Tsuga canadensis) p.238 



9. Leaf about 2 cm. or more long, without leaf-stalk, leaving a flat 

 or only slightly raised scar when detached 10 



10. Buds small, nearly spherical to broadly ovate, their scales covered 



and glued together by resinous coating; leaf-scars flat 



Balsam Fir (Ahies halsamea) p.236 



10. Buds larger, narrow conical, without resinous coating; leaf-scars 

 slightly raised Ooug;las Fir (Pseudotsuga taxifolia) p.234 



11. Leaf-scars opposite or in 3's, therefore 2 or 3 at a node 12 



11. Leaf-scars alternate, therefore only 1 at a node 16 



12. Leaf-scars or some of them 3 at a node; bundle-scars in an 

 ellipse; terminal bud absent Catalpa (Catalpa) p.428 



12. Leaf-scars always 2 at a node; bundle-scars not in an ellipse; 

 terminal bud present 13 



13. Leaf buds with only a single pair of scales; lateral buds, at least 



the upper ones, covered by persistent bases of leaf-stalks 



FloweriuR Dogwood (Cornus florida) p.418 



13. Leaf buds with 2 or more pairs of scales; lateral buds not covered 

 by persistent bases of leaf-stalks 14 



