GENUS PINUS 



51 



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. 

 Soft Pines, are uninodal and the cones are dehiscent at maturity, but the 

 nous species is shown in the occasional appearance of the oblique cone as 

 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 

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

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



All the species, like the 

 trend toward the seroti- 

 a varietal form of a few 



P. tropicalis. These two 

 and are the only Ameri- 



Cones deciduous at maturity. 

 Cones ovate or ovate-conic. 



Conelet with tuberculate or entire scales. 



Resin-ducts external and medial 25. 



Resin-ducts septal and external 26. 



Conelet with mucronate scales. 

 Resin-ducts mostly external. 

 Conelet pedunculate, erect. 



Cone nut-brown 27. 



Cone dull tawny yellow 28. 



Conelet pedunculate, reflexed 29. 



Conelet subsessile, erect 30. 



Resin-ducts mostly medial. 



Bark-formation late 31. 



Bark-formation early. 



Cone nut-brown 32. 



Cone lustrous tawny yellow 33. 



Cones narrow cylindrical 34. 



Cones tenaciously persistent. 



Leaves stout, relatively short 35. 



Leaves slender, relatively long 36. 



resmosa 

 tropicalis 



Massoniana 

 densiflora 



sylvestris 

 montana 



luchuensis 



Thunbergii 



nigra 



Merkusii 



sinensis 

 insularis 



25. PINUS RESINOSA 



1789 P. RESINOSA Alton, 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. 



