ENGELMANN REVISION OF THE GENUS PINUS, ETC. 1 77 



P. Halefensis,^'^ Pyrenaica.''-^ 



B. Ducts parenchymatous. 



a. Cones subterminal. 



§ 6. PoNDEROS.E.— Mostly American, with three Old World species. 



* Leaves in fives, ducts usually free of strengthening cells. 

 Pseudos.trobi.—Q^x\ir2>\ America and Mexico to Arizona and 

 California. 



P. let'ophylla,^^ ie?iuifolia, filifolia}' Psetido-Strobus, Monteziimce^^ [Hart- 

 vjegit)^ Torreya7ta,^'^ Arizonica."^^ 



** Leaves in threes, sometimes in fours or fives, their sheaths 

 persistent; strengthening cells under the epidermis, around 

 ducts, and usually also near the fibro-vascular bundles. — 

 EuponderoscE. — Northwestern America, Mexico, and Canary 

 Islands. 

 P. Engehnanni,'^'^ fojtderosa'^' {Jeffreyi^, Cafiarietisis.-^ 



*** 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'^^ (^Atistriaca), Thunbergii,-'^ contorta-' {Murrayana'). 



b. Cones lateral. 



§ 7. T.ED.E. — Mostly American, only one Old World species. 



* Leaves in threes, ducts mostly without strengthening cells. 

 Eutced(E. — North America to Mexico. 



P. Sabintana,'^'^ Coulteri,'^^ insignis,'^^ tuberculata,^^ Tceda,^'^ rtgida^'^ 

 [seroiina^?), Gi'eggit, Teocote, patula.^^ 



* * Leaves in twos ; cones with very stout prickles. Pungentes. 



t Ducts without strengthening cells. — North America. 

 P. inops {clausa^'^), j>U7igens,^^ muricata.^^ 



1 1 Ducts surrounded by strengthening cells. — Southern Eu- 

 rope. 

 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.,^'^ Baiiksiana.'^^ 



C. Ducts internal. 

 § 8. AusTRALES. Leaves in twos to fives; timber very heavy and 

 resinous. — Southeastern North America, West Indies, and one spe- 

 cies in Mexico, 

 iv — 12 



