12 PIXACEAE 



Leaves in 4's or 5's, with solitary flbro-vascular bundles and more or less deciduous 



sheaths ; spines of the cone-scales long and slender. 1. P. arislata. 



Leaves in 2's or 3's, with usually two flbro-vascular bundles and persistent sheaths; spines 

 of the cone-scales short or none. 

 Cones 6-15 cm. long and 5-6 cm. in diameter; leaves 8-25 cm. long. 



Leaves 12-25 cm. long; cones 8-15 cm. long, elongated-ovoid. 2. P. ponderosa. 



Leaves 8-15 cm. long; cones 6-9 cm. long, rounded-ovoid. 3. P. scopulorum. 



Cones 3-5 cm. long and about 3 cm. in diameter. 



Cones spreading, or somewhat reflexed ; scales with evident dorsal spines. 



4. P. Murrayana. 

 Cones erect, more or less incurved ; scales unarmed or nearly so, at least at matur- 

 ity- 5. P. Banksiana. 



1. P. aristata Engelm. A low stunted tree, 3-15 m. high; bark of the 

 trunks dull reddish bro%vn, shallowly furrowed; that of the smaller trunks and 

 limbs smooth, milky- white; leaves dark green above, glaucous beneath, 3-4 cm. 

 long, in fascicles of 5, crowded toward the ends of the branches; staminate 

 flowers orange-red; pistillate ones dark purple; cones sessile, 7-10 cm. long, 

 ellipsoid, obtuse; scales with a thickened purple-brown back. Bristle-cone 

 Pine. High mountains: Colo.— N.M.— Cahf.— Nev. Mont.—Subalp. 



2. P. ponderosa Dougl. A tree 35-60 m. high, with a trunk 1-2 m. in 

 diameter; bark in older trees 5-10 cm. thick, dark brown, separating into cin- 

 namon-red scales; leaves in fascicles of 3, yellowish green, 12-25 cm. long; 

 staminate flowers yellow; pistillate ones dark red; cones broadly ellipsoid, hori- 

 zontal, subsessUe, 1-1.5 dm. long. Bull Pine. Slopes and valleys: B.C. — 

 Mont. — -Ida.— Calif. Submont. 



3. P. scopulorum (Engehn.) Lemmon. A tree 25-30 m. high; bark thick, 

 deeply divided into plates; leaves in 2's or 3's, yellowish green, 8-15 cm. long; 

 staminate flowers yellow; pistillate ones purple; cones conic-ovoid, horizontal. 

 P. ponderosa scopulorum Engehn. Rock Pine, Bull Pine.- Hills and moun- 

 tains: S.D. — Neb. — N. M.— Ariz. — Mont. Subtiiont. — Mont. 



4. P. Murrayana Balf. A tree 20-30 m., sometimes 45 m. high; bark of the 

 trunk about 5 mm. thick, close and firm, covered with appressed scales, orange- 

 brown; branches light orange; leaves yellowish green, 3-7 cm., usually about 5 

 cm. long; flowers orange-red; cones spreading, 3-4 cm. long, short-ovoid. P. 

 conlorta Murrayana Engehn. Lodge-pole Pine. Hills and mountains: Sask. 

 (Cj'press Hills) — Colo. — Calif. — Alaska. Mont. 



5. P. Banksiana Lamb. A tree 10-20 m., rarely 30 m. high; bark dark 

 brown, tinged with red, irregularly furrowed ; leaves in rather remote clusters of 

 2, dark green, 2-'i cm. long; staminate flowers yellow; pistillate ones dark purple; 

 cones conic-ovoid, erect and incurved, 3-5 cm. long, dull pm-ple or green, turn- 

 ing yellow and shining. P. divaricata (Ait.) Gordon. Gr.\y or Northern 

 Scrub Pine, Banksian Pine. Sandy soil: N.S. — n N.Y. — Minn.— Alta. — Mack. 

 Boreal. 



2. CARYOPITYS Small. Nut-pines, Pinons. 



Monoecious evergreen trees or shrubs, with 2 kinds of leaves as in Pinus; 

 secondarj' leaves with solitary flbro-vascular bundles, in fascicles of 2-4, or in 

 one species usually solitary, surrounded by a deciduous sheath. Staminate 

 aments as in the preceding. Pistillate cones subsessile just below the terminal 

 bud; scales in rather few series. Cones maturing the second season; scales 

 becoming leathery, thick, with a dorsal thickening, usually with a small spine- 

 tip. Seeds large and edible, with a very narrow wing or mere margin, remain- 

 ing attached to the scale when the seed falls. 



Cones about 3 cm. long; leaves usually in pairs, seldom in threes. 1. C. cdulis. 



Cones 4—5 cm. long; leaves singly or sometimes in pairs. 2 C. monophylla. 



1. C. edulis (Engelm.) Small. A tree 6-12 m. high; bark of the trunk 

 divided into ridges and brown scales; that of the young branches orange or yel- 

 low; foHage-leaves in clusters of 2's, rarely in 3's, semi-terete or triangular, 2-4 

 cm. long; staminate flowers dark red; cones very short-peduncled, spreading, 

 ehort-ovoid, 2-^ cm. long, almost as wide. Pinus edulis Y^ngchn. Pinon, Nut- 

 pine. Foot-hills: Wyo. — w Tex. — Ariz. — Utah; Mex. Son.-rSubmoyit. 



