ANALYTICAL KEY 



a. TREES. (For next related division go to page g*.) 



b. Leaves small or narrow, usually needle- or awl-shaped (Pine family). 

 c. Leaves always present, i. e., tree evergreen. 



d. Leaves in clusters of two or more on ordinary branches (Pine). 

 e. Leaves five in a cluster. WHITE PINE, PINUS STROBUS (p. 30). 



e. Leaves two or three in a cluster. 

 f. Cone scales without spines or prickles. 



g. Leaves long, i. e., 9-16 cm. RED PINE, PINUS RESINOSA (p. 31). 



g. Leaves short, i. e., 2-4 cm. JACK PINE, PINUS BANKSIANA (p. 31). 

 f. Cone scales armed with a spine or prickle. 

 g. Leaves rigid. 



h. Leaves two in a cluster. JACK PINE, PINUS BANKSIANA (p. 31). 

 h. Leaves three in a cluster. PITCH PINE, PINUS RIGIDA (p. 31). 



g. Leaves flaccid. 

 h. Scale spine minute, t. e., i mm. or less in length. 



YELLOW PINE, PINUS ECHINATA (p. 31). 

 h. Scale spine 23 mm. in length. 



JERSEY PINE, PINUS VIRGINIANA (p. 31). 

 d. Leaves single. 

 e. Leaves not opposite, needle-shaped. 



HEMLOCK, TSUGA CANADENSIS (p. 31). 

 e. Leaves opposite. 

 f. Fruit a cone of separate scales; leaves scale-shaped. 



ARBOR VITAE, THUJA OCCIDENT ALIS (p. 32). 

 f. Fruit a berry; leaves needle- or scale-shaped. 



RED CEDAR, JUNIPERUS VIRGINIANA (p. 32). 



c. Leaves absent part of the year, t. e., tree deciduous; leaves many in a 

 cluster on a short branch. TAMARACK, LARIX LARICINA (p. 31). 



b. Leaves not needle- or awl-shaped; trees not evergreen. 

 c. Leaves and branches opposite (p. 6). 

 d. Inflorescence white. 

 e. Corollas greenish, surrounded by a showy white involucre. 



FLOWERING DOGWOOD, CORNUS FLORIDA (p. 100). 

 e. Corollas white; involucre wanting. 



BLACK HAW, VIBURNUM LENTAGO (p. 119). 

 d. Inflorescence not white. 



e. Flowers appearing decidedly before the leaves (p. 6). 

 f. Bark whitish to grayish, smooth except on basal parts of large trees; 



leaves simple (Maple). 

 g. Petals none; fruit woolly; leaves deeply lobed. 



SILVER MAPLE, ACER SACCHARINUM (p. 91). 

 g. Petals present; fruit smooth; leaves somewhat lobed. 



RED MAPLE, ACER RUBRUM (p. 91). 

 f. Bark rough except on the smaller branches; twigs coarse; leaves 



compound (Ash). 

 g. Old bark deeply furrowed; calyx present. 



WHITE ASH, FRAXINUS AMERICANA (p. 106). 



* The words "for next related division go to" are to be understood with sim- 

 ilar references which follow. 



5 



