PICEA. 



423 



fairly natural one and includes about seventeen species, but some of 

 them are not distinguished by very definite characters, and may 

 hereafter be reduced to varieties of more common types.* 



The essential characters of the genus may be thus formulated : 



Flowers monoecious in the axils of leaves of shoots of the preceding- 

 year ; the ovuliferous flowers occasionally terminal. 



Staminate flowers stipitate, ovoid or cylindric, the stipes (stalk) 

 surrounded by numerous involucral bracts in two three series. Anthers 

 spirally arranged around an axis, with a crimson or yellow connective 

 dilated into a rounded crest and opening longitudinally. 



Ovuliferous flowers shortly stipitate, cylindric, composed of numerous scales 



usually broader than long, spirally imbricated in many ranks, and bearing 



on the ventral (inner) face, near the base, two anatropous (inverted) ovules. 



Cones cylindric, or some slight modification of that form, rarely ovoid, 



at first erect but ultimately pendulous, attaining maturity the first 



Fig. 107. 1, Staminate flowers of Picea Smithiana, nat. size. 2 and 3, side and front view of 

 anther before dehiscence. 4 and 5, after dehiscence, enlarged five diameters. 6, Pollen grains, 

 enlarged 120 diameters. 



season and falling off after the dispersion of the seeds in the following- 

 winter, or persistent longer. Scales entire, denticulate or erose, gradually 

 decreasing in size towards the two ends of the cone, always longer 

 than the bract and bearing on the inner face two winged seeds, f 

 The Spruce Firs are evergreen trees, in their best aspect of conical 

 or pyramidal outline. The trunk is tall and tapering, clothed with 

 relatively thin bark, sometimes strongly buttressed at the base and 

 regularly feathered with branches so long as it continues to increase in 

 height ; in old age usually denuded of branches for the greater part of 



* E.g., Picea exceha and P. obovata ; P. Glehnii and P. Alcockiana ; P. alba and P. 

 Engelmanni ; P. nigra and P. rubra. 



f The most important botanical characters by which Picea is distinguished from Abies 

 are : - The leaves are stomatiferous on the upper surface ; the dehiscence of the anthers is 

 longitudinal (not transverse) ; the scales of the cone are always longer than the bract, and 

 persist after the dispersion of the seeds. Very obvious differences are also observable in 

 the pendulous (not erect) cones with differently shaped scales ; in the four-angled spine- 

 tipped leaves of the greater number, and in the general habit of most of the species. 



