42 



47* P- Chihualiuana. 



*'^'** Leaves in twos. Lariciones, — Europe to Asia and W. 

 America. 



48. P. Laricio, (49. Austriaca), 50. Thunbergii, 51. contorta, 

 (52. Murrayana.) 



b. Cones lateral. 



7. Taedae. — Mostly American, only one Old World species. 



*. Leaves in threes. Eutaedae, — North America to Mexico. 



53. P. Sabiniana, 54. Coulteri, 55. insignis, 56. tuberculata. 



57. Taeda, 58, rigida, (59. serotina), 60. Greggii. 61. Teo- 

 cote. 62. patula. 



** Leaves in twos ; cones with very stout prickles. Fun- 

 gcntes, 



f Ducts without strengthening cells. — North America. 

 dl. P. inops, •(64. clausa), 65. pungens, 66. muricata. 



ff Ducts surrounded by strengthening cells. — Southern 

 Europe. 



67. P. Pinaster, 



*** Leaves in twos, or in the first often also in threes ; 

 cones Avith weak or deciduous prickles. Mites. — Eastern 

 North America. 



68. P. mitis, 69. glabra, 70. 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. Eiiatistrahs, 

 71. P. oocarpa, 72. occidentalis, 73. australis. 



** Cones lateral or mostly so ; leaves in twos to threes. 

 Elliottiae. 



74. P. EUiottii, 75. Cubensis, 76. Wrightii. 



Notes. 



Nos. 15-18. Cembroides. Dr. Englemann considers it an open 

 question whether these four species may not properly be united into 

 one.— 19, 20 must be united.— 21-23. a very natural group— 27 P 

 densiflora, Sieb. & Zucc, sometimes cultivated under the name of the 

 follmying.— 28. P. Massoniana, Lamb. Parlat., not Sieb. & Zucc or 

 Endhch., that IS No. 50, P, Thunhergii, Pari— 20. P MerkusH 



* 



