ENGEI.MANN REVISION OF THE GENUS PINUS, ETC. I 79 



6. P. Balfouriana, Jeffrey, and P. artsfata, Engelm., of the Colorado 

 Rocky Mountains, are identical in leaf-structure and in flowers and must 

 be united, though the cone of the former is elongated, often even cylindri- 

 cal, the apophyses thicker and peculiarly spongy, and at maturity unarm- 

 €d, while the other has an oval cone with thinner scales and awnlike 

 prickles. In Utah and Nevada a form occurs with cones like the latter, 

 but with short, stout, recurved prickles. Parlatore enumerates aristata, 

 but does not mention Bal/otiriana. 



7. P. Khasia, Royle, and its two allies, form a very natural little group. 

 Leaves in this species with 2 dorsal ducts; strengthening cells very slight 

 and only in the corners; male flowers i inch long, slender ; involucral 

 bracts I2 to 14, exterior half as long as the inner ones, all apparently 

 pointed; anthers | to 1 line long; crest only h. line wide, nearly entire. 



P. hisularis, Endl., has similar leaves, ducts often indistinct, strength- 

 ening cells slight in the corners and some scattered under the epidermis 

 and also near the vessels ; male flowers i inch long; involucral bracts 

 about 8. outer pair more than half as long as the inner ones; anthers less 

 than I line long, crest nearly entire. 



P. longlfolia, Roxb. Ducts few (in Wallich's specimens), or many (in 

 Hooker and Thompson's), or none at all (Hooker's; Thuret's cult.); 

 strengthening cells strongly developed in bundles all around leaf; bracts 

 large, strongly fringed, deciduous; male flowers larger than in last, i-ii 

 inches long, thicker; anthers i^ lines long; crest \ line wide, strongly 

 fringe-denticulate; involucre not seen. The thick bundles of strengthen- 

 ing cells and the larger male flowers readily distinguish it from the two 



others. 



8. P. fnoniana, Duroi. is so well characterized that it is inconceivable 

 how it could have been taken for a variety of P. sylvestrts, unless some 

 hybrid forms, which are said to occur, have created the difficulty. The 

 involucral bracts are always more numerous, usually about 6, the anthers 

 crested, the female aments subsessile, and the young cone erect; in syives- 

 tris the involucral bracts rarely exceed 3, the crest of the anthers is reduced 

 to a small ridge or a few teeth, the female ament is not longer than its pe- 

 duncle and becomes recurved soon after flowering. 



9. P. resinosa, Ait., is the only American representative of this well 

 characterized group. The 6 involucral scales are articulated in the middle, 

 the upper part falling oft" early (p. 16S) ; ducts almost always only 2 on the 

 upper side of the leaf. 



10. P. densijlora^ Sieb. & Zucc. Leaves with numerous ducts, mostly 

 surrounded by strengthening cells, also some of these within the sheath ; 

 in a few instances, in Japanese as well as in cultivated specimens, the 

 strengthening cells are almost wanting; male flowers oval, only 2 to 3 lines 

 long, in an elongated spike; involucrum of 3 or 4 or rarely 5 or 6 bracts 

 of equal length; anthers only i line long, or less, with a small, slightly 

 denticulate crest. Only in Japan. Sometimes cultivated under the name 

 of the following. 



