TREES AND SHRUBS 



25 



Class I. GYMNOSPERMAE. 



Trees (and a few shrubby species) with resin- 

 ous wood and needle-shaped evergreen 

 leaves; fruit a cone consisting of several to 

 many fleshy or woody scales; seeds borne 

 at the base of the scales. 



Low desert shrubs with terete, yellowish green 

 stems; leaves reduced to 2 or 3 membran- 

 ous scales at the nodes; fruit with 1 to 3 

 seeds tightly enclosed in several or numer- 

 ous membranous scales, not resembling a 

 cone. 



Order I. PINALES. 



Order II. GNETALES. 



Order I. PINALES. 



Buds scaly; cones oblong, dry; ovules Inverted; 



leaves in ours about 1 inch long or more. 

 Buds not scaly; cones spherical, fleshy at least 



when young; ovules erect; leaves short and 



scalelike, mostly only a few millimeters 



long. 



Pinaceae. 



2. JUNIPERACEAE. 



I. PINACEAE. Pine Family. 

 Mostly evergreen monoecious resin-yielding shrubs or trees, 

 often conic in outline. Leaves rigid, needle-like or flat, alternate, 

 opposite, whorled or in clusters with sheathed bases, anthers 2- 

 several-celled, in more or less elongated cones. Pollen-grains 

 globose ellipsoidal or lobed. Pistillate cones solitary or clustered, 

 consisting of numerous spirally disposed bracted scales. Ovales 

 inverted usually 2 at the base of each scale. Fruit a dry cone of 

 many scales. Seeds usually 2, winged. Cotyledons 2-16. 



Leaves fascicled, enclosed by sheaths at base, 

 at least when young; cones maturing the 

 second year. • 1. Pinus. 



Leaves solitary, not sheathed; cones maturing 

 the first year. 

 Branches rough with persistent leaf- 

 bases; leaves quadrangular, falling off 

 when dried; cone scales thin and per- 

 sistent; cones pendulous. 2. Picea. 

 Branches smooth; leaves flat, persistent In 

 dried specimens. 

 Cones erect, scales deciduous; leaves ses- 

 sile leaving circular scars. 3. Abies. 

 Cones pendulous, scales persistent; bracts 

 of the cone scales conspicuously ex- 



serted, 3-parted; leaves petioled, leaving 4. Pseudotsuga. 

 oval scars. 



