GENUS PINUS 



<1 



X. LARICIONES 



Pits of the ray-cells large. Cells of the leaf-hypoderm uniform. Spring-shoots uninodal. Cones 

 dehiscent at maturity. 



This group represents the first stage in the evolution of the Hard Pines. All the species, like the 

 Soft Pines, are uninodal and the cones are dehiscent at maturity, but the trend toward the seroti- 

 nous species is shown in the occasional appearance of the oblique cone as a varietal form of a few 

 species, and in the persistent cone of the last two species of this group. 



All the species of this group are of the Old World except P. resinosa and P. tropicalis. These two 

 are the only American Pines combining large pits with dentate tracheids, and are the only Ameri- 

 can Hard Pines with external resin-ducts of the leaf. 



Cones deciduous at maturity. 

 Cones ovate or ovate-conic. 



Conelet with tuberculate or entire scales. 



Resin-ducts external and medial 25. resinosa "^ 



Resin-ducts septal and external 26. tropicalis 



Conelet with mucronate scales. 

 Resin-ducts mostly external. 

 Conelet pedunculate, erect. 



Cone nut-brown 27. Massoniana 



Cone dull tawny yellow 28. densiflora 



Conelet pedunculate, reflexed 29. sylvestris 



Conelet subsessile, erect 30. montana 



Resin-ducts mostly medial. 



Bark-formation late 31. luchuensis 



Bark-formation early. 



Cone nut-brown 32. Thunbergii 



Cone lustrous tawny yellow 33. nigra 



Cones narrow cylindrical 34. Merkusii 



Cones tenaciously persistent. 



Leaves stout, relatively short 35. sinensis 



Leaves slender, relatively long 36. insularis 



25. PINUS RESINOSA 



1789 P. RESINOSA Aiton, Hort. Kew. iii. 367. 



1810 P. RUBRA Michaux f. Hist. Arbr. Am. i. 45, t. 1. 



Spring-shoots uninodal. Leaves binate, from 12 to 17 cm. long; resin-ducts external or external 

 and medial; hypoderm uniform and inconspicuous. Scales of the conelet mutic. Cones from 4 to 6 

 cm. long, subsessile, symmetrical, deciduous the third year, leaving a few basal scales on the tree; 

 apophyses sublustrous, nut-brown, somewhat thickened along a transverse keel. 



From Nova Scotia and Lake St. John this species ranges westward to the Winnipeg River and 

 southward into Minnesota, Michigan, northern New York and eastern Massachusetts, with rare 

 occurrence on the mountains of Pennsylvania. Under cultivation it is a beautiful tree, adapted to 

 cold-temperate climates. It was considered by Loiseleur (1812) and by Spach (1842) to be a vari- 

 ety of P. nigra (laricio). The two species vary in the color of the cone, the anatomy of the leaves, 

 the buds, and in the armature of the conelet. A fallen cone of this species is moreover usually im- 

 perfect from the loss of a few basal scales. 



Plate XIX. 



Fig. 170, Cone and enlarged conelet. 



Fig. 171, Leaf -fascicle and magnified leaf -section. 



