| Spring-shoots uninodal. | |
| Resin-ducts mostly internal | 48. Pringlei |
| Resin-ducts mostly septal | 49. oocarpa |
| Spring-shoots multinodal. | |
| Cones symmetrical. | |
| Leaf-hypoderm not biform. | |
| Bark-formation late | 50. halepensis |
| Bark-formation early | 51. pinaster |
| Leaf-hypoderm biform. | |
| Cones with slender spines. | |
| Leaves binate. | |
| Cones dehiscent at maturity | 52. virginiana |
| Cones serotinous | 53. clausa |
| Leaves ternate. | |
| Cones dehiscent at maturity | 54. rigida |
| Cones serotinous | 55. serotina |
| Cones with stout spines | 56. pungens |
| Cones oblique or unsymmetrical. | |
| Cones and leaves very short, not exceeding 6 cm. | |
| Cones curved or warped | 57. Banksiana |
| Cones straight | 58. contorta |
| Cones and leaves much longer, more than 7 cm. | |
| Posterior cone-scales gradually larger than anterior scales. | |
| Bark-formation late | 59. Greggii |
| Bark-formation early | 60. patula |
| Posterior cone-scales abruptly larger than anterior scales. | |
| Cones with very stout spines | 61. muricata |
| Cones with minute or deciduous prickles. | |
| Bark-formation late | 62. attenuata |
| Bark-formation early | 63. radiata |
48. PINUS PRINGLEI
1905 P. Pringlei Shaw in Sargent, Trees & Shrubs, i. 211, t. 100.
Spring-shoots uninodal, sometimes pruinose. Leaves ternate, from 15 to 25 cm. long; resin-ducts internal or with an occasional septal duct, hypoderm biform, in thick masses, often projecting far into the green tissue and sometimes touching the endoderm. Conelets mucronate. Cones from 5 to 10 cm. long, reflexed on a rigid peduncle, subsymmetrical or more or less oblique, tenaciously persistent, often serotinous; apophyses sublustrous tawny yellow or fulvous brown, convex, the posterior scales often more prominently developed, the mucro usually wanting; seed with a perceptibly thickened wing-blade.
A tree with long erect bright green foliage, confined, so far as known, to the subtropical altitudes of western Mexico. As it grows in Uruapan, Michoacan, there are two forms of the cone, large and small, both with the same long rigid leaf.
Figs. 268, 269. Three cones and seed. Fig. 270, Leaf-fascicle and magnified leaf-section.
49. PINUS OOCARPA
- 1838 P. oocarpa Schiede in Linnaea, xii. 491.
- 1842 P. oocarpoides Lindley ex Loudon, Encycl. 1118.