REVISION OF THE GENUS PINUS. 369 
* * Leaves in twos ; strengthening aie abundant, principally around ducts ; fructification biennial, cones 
and seeds small, wings large. Husylvestres. — Old World, one species in N pietheaiibetsi America, 
P. sylvestris,’ montana, resinosa,® densiflora,” Massoniana 1 Merkusii.! 
*** Leaves in twos; strengthening cells under the epidermis and around ducts ; fructification triennial, 
cones and seeds large, wings rudimentary. — A single Mediterranean species. 
P. Pinea. 
&. Cones lateral. 
§ 5. Ha .epenses. — Old World. 
* Leaves in threes, their sheaths deciduous ; umbo very prominent ; wings shorter than the large seeds. 
Gerardiane.— Asia 
P. Gerardiana,® Bungeana. 
* * Leaves in twos, their sheaths persistent ; cones smoothish ; wings much longer than the seeds. Euhale- 
penses. — Mediterranean regions. 
P. Halepensis,'* Pyrenaica. [177] 
B. Ducts parenchymatous. 
a. Cones subterminal. 
§ 6. PonpERos&.— Mostly American, with three Old World species, 
* Leaves in fives, ducts ley free of strengthening cells. Pseudostrobi. — Central America and Mexico to : 
Arizona and Californi 
P. leiophylla, tenuifolia, ane Pseudo-Strobus, Montezume ® (Hartwegii), Torreyana, ® Arizonica.™ 
* * Leaves in threes, sometimes in fours or fives, their sheaths persistent ; strengthening cells under the epi- 
dermis, around ducts, and usually also near the fibro-vascular bundles. Hupouderose. — Northwestern 
America, Mexico, and Canary Islands. 
P. Engelmanni, * ponderosa™ (Jeffreyi), Canariensis.*8 
* * * Leaves in threes, their sheaths deciduous. — Mexico and Arizona. 
P. Chihuahuana.* 
* * * * Leaves in twos, generally with some strengthening cells around ducts. Lariciones.— Europe to Asia 
and W. America. 
P. Laricio*® (Austriaca), Thunbergii,® contorta ™ (Murrayana). 
4. Cones lateral. 
§ 7. Tapa. — Mostly American, only one Old World species. 
* Leaves in threes, ducts mostly without strengthening cells. Hutede.— North America to Mexico. 
P. Sabiniana,® Coulteri,® insignis,® tuberculata,® Teda,® rigida * (serotina **), Greggit, Teocote, patula.® 
* * Leaves in twos ; cones with very stout prickles. Pungentes. 
+ Ducts without strengthening cells. — North America. 
P. inops(clausa **), pungens,® muricata.™ 
+ Ducts surrounded by strengthening cells. — Southern Europe. 
P. Pinaster.® 
* * * Leaves in twos, or in the first often also in threes ; cones with weak or deciduous prickles. Mites. — 
Eastern North America. 
P. mitis,® glabra,® Banksiana.” 
C. Ducts internal. 
=§ 8. AusTRALES. Leaves in twos to fives; timber very heavy and resinous, — Southeastern North America, West 
Indies, and one species in Mexico. 
* Cones subterminal ; leaves in threes to fives. Huaustrales, [178] 
P. oocarpa," occidentalis, australis. 
nes lateral or mostly so; leaves in twos to threes. lliottia. 
P. Elliottii,® Cubensis,4 Wrightii.™ 
47 
