26 PINACEAE (PINE FAMILY) 



Stems very short, densely tufted 1. S. densa. 



Steins creeping, 5-10 cm. long. 



Leaves with a conspicuous white awn 2. S. rupestris. 



Leaves obtuse, not awned . . . . . . . . . 3. S. mutica. 



1. Selaginella densa Rydb. Mem. N. Y. Bot. Gard. 1: 7. 1900. Densely 

 tufted; sterile branches very short: leaves crowded and many-ranked, 3-5 mm. 

 long, ciliate on the margin and tipped with a white bristle: fertile branches 

 1-2 cm. long; bracts imbricated, 4-ranked, triangular-ovate, deeply grooved 

 dorsally, tipped with a bristle shorter than those of the leaves. The most 

 frequent species in our range; Colorado and Utah to Montana. 



2. Selaginella rupestris L. Sp. PI. 1101. 1753. Stems creeping, 5-10 cm. 

 long, somewhat flexuous, with ascending tips, rooting throughout their whole 

 length, more or less branched: leaves imbricated in 8 ranks, ciliate-margined 

 and tipped with a white awn: spikes sharply quadrangular, 10-20 mm. long. 

 Across the continent northward; apparently in Colorado, though ours belong 

 mostly to the following variety. 



2a. Selaginella rupestris Fendleri Underw. Bull..Torr. Bot. Club 25: 127. 

 1898. Differs from the species in the laxer leaves which are tipped with a 

 shorter awn and have denticulate cilia on the margins: spikes flabby and flex- 

 uous: megaspores coarsely areolate. Colorado and New Mexico. 



3. Selaginella mutica D. C. Eat., Underw. Bull. Torr. Club 25: 128. 1898. 

 Stems creeping, rather rigid, 8-15 cm. long, pinnately branched: leaves 6- 

 ranked, closely imbricated, only 1 mm. long, obtuse, grooved on the back, 

 devoid of terminal seta but with spreading marginal cilia : spike quadrangular, 

 its bracts acute and sometimes submucronate. Colorado to Arizona and New 

 Mexico. 



GYMNOSPERMS 



Trees and shrubs representing an ancient and at one time very abundant 

 flora, now reduced to a relatively small number of genera and species, mostly 

 Evergreens. Plants monoecious or dioecious. Ovules naked, i. e., not in- 

 closed by the carpel; the latter is represented by a scale or a bract or in some 

 instances is wholly wanting. Cotyledons two or often several in a whorl. 



8. PINACEAE Lindl. PINE FAMILY 



Trees or sometimes shrubs, evergreen, more or less resinous. Leaves needle- 

 shaped or scale-like. Staminate and pistillate cones on the same individual 

 (except in Juniperus); the staminate clusters of an indefinite number of 

 stamens only; the pistillate of few to many scales which become in fruit a dry 

 cone, with two or more ovules at or on the base of each scale. In Juniperus 

 the fruit is small, semi-fleshy, and berry-like. 



Fruits large, becoming dry cones. 



Leaves in bundles of 2-5 (rarely solitary); cones of thickened corky 



scales, the seeds maturing the second year 1. Pinus. 



Leaves single, usually less than 3 cm. long; cones coriaceous; seeds ma- 

 turing the first year. 

 Branchlets rough from the prominent persistent leaf-bases; cones 



pendulous .......... 2. Picea. 



Branches smooth, the leaves disarticulating close to the bark leaving 



a smooth oval scar. 

 Cones erect; the bracts aristate or mucronate . . . .3. Abies. 



Cones pendulous; the bracts exserted and 3-pointed . . .4. Pseudotsuga. 

 Fruits small, semi-fleshy and berry-like 5. Juniperus. 



1. PINUS L. PINE 



Trees. Leaves of two kinds, the primary ones early deciduous, the secondary 

 (ordinary foliage) slender, needle-shaped, in bundles of 2-5 (mostly soli- 



