60 CONTRIBUTION'S FROM THE NATIONAL HERBARIUM. 



7. SEIAGrlNELLACEAE. Selaginella Family. 



1. SELAGINELLA Beauv. 



Leaves very numerous, alike, appressed, widely overlapping, many-ranked, linear- 

 lanceolate, ending in a slender whitish awn 1. s. nipestris. 



Leaves few, of 2 kinds, -1-ranked, spreading in 2 plane?, ovate, acute or cuspidate. 



2. S. apoda. 



1. Selaginella rupestris (L.) Spring. 



Exposed rocky bluffs; found only in vicinity of Great Falls, both sides of the river. 

 Ont. and eastern U. S. 



2. Selaginella apoda (L.) Fernald. 



Low moist situations, usually in partial shade; common. Me. to the Gulf states, 

 westward, (S. apus Spring.) 



8. ISOETACEAE. Quillwort Family. 



1. ISOETES L. Quillwojit. 



Leaves 50-100, erect, 30-60 cm. long, with bast bundles.. ..1. I. engelmanni valida. 

 Leaves 10-30, spreading or recurved, 3-25 cm. long, without baet bundles. 



2. I. saccharata. 



1. Isoetes engelmanni valida Engelm. 



Temporary pools among rocks; Virginia shore of the Potomac, between Sandy Land- 

 ing and Great Falls; rare. N. J. to Va. 



2. Isoetes saccharata Engelm. 



Shallow water between tides, on gravel and sand; banks of the Potomac at Fourmile 

 Run, Hunting Creek, and Mount Vernon; not uncommon. Mass. to Va. 

 Extremely variable, several forms having been described. 



9. PINACEAE. Pine Family. 



Leaves scalelike or awl-shaped, opposite 4. JUNIPERUS. 



Leaves linear, needle-like. 

 Leaves in fascicles. 1. piNTJS. 



Leaves solitary. 

 Leaves stiff, about 10 mm. long, obtuse, persistent, dark green above, pale 



beneath; cones oblong, 2 cm. long or more, the scales rounded... 2. TSUGA. 

 Leaves slender, about 15 mm. long, acute, deciduous, light green on both faces; 



cones globose or nearly so, the scales thick, woody 3. TAXODITJM. 



1. PINUS L. Pine. 



Leaves 5 in a fascicle; cones more than 9 cm. long, maturing the first year, the scales 



without bristles.. L P stroDUSi 



Leaves 2 or 3 in a fascicle; cones less than 9 cm. long, maturing the second year, each 

 scale bearing a bristle near the apex. 

 Leaves 3 in a fascicle. 



Leaves 7-12 cm. long; cones ovoid, 3.5-7 cm. long 2. P. rigida. 



Leaves 13-24 cm. long; cones oblong, 7-12 cm. long 3. p. taeda. 



Leaves 2 in a fascicle. 



Leaves slender, about 1 mm. in diameter, 6 cm. long or more 4. P. echinata. 



Leaves stout, about 2 mm. in diameter and 4 cm. long. 



Cone scales tipped with a slender straight fragile prickle 5. P, virginiana. 



Cone scales tipped with a thick curved woody persistent prickle. 



6. P. pungens. 



