181] ENGELMANN—REVISION OF THE GENUS PINUS, ETC. 21 
cult, a pose to “ig apid circumscribe the species; for the present I feel 
obliged to unite with iteven P. Hartwegii and a number of others already 
included by Sartetoes! ad a closer study on the Mexican mountains will 
decide whether or not several well characterized species may be hidden 
among them. All those that I could examine have numerous and strong 
bundles of strengthening cells under the epidermis and also near the ves- 
sels, but none around the ducts. 
19. P. Torreyana; Parry, has the same structure of the leaves. The 
ame was published in the Botany of the Mexican Boundary, 1859, and is 
therefore older than P. lophosperma, Lindl. of 1860. 
Oo. rizontca, Engelm. in Bot. Wheeler, p. 260, has also this struc- 
ture and is thus distinguished from P. ponderosa, besides being five-leaved. 
. P. Engelmanni, Carritre, Conif. p. 356; P. macrophylla, Engelm- 
in Wislis, Mem. p. 103, note 25, is a tree only known from Wislizenu . 
single specimen gathered in 1846 on the mountains of Cosiquiriachi, 1 
of Chihuahua, where it is said to be abundant. wees name was changed 
Carriére because it clashed with Lindley’s prior one; this, ho sami, tx is 
ieee by Parlatore to be a form of Montezuma, tet which I have not 
been ine. Our plant differs from this species by having its very 
stout leaves in threes and fours and very rarely in fives, in the strongly 
developed strengthening cells under the epidermis and also a round the 
ducts, and inthe form of the cone. Parlatore does not mention it. 
22. P. ponderosa, Douglas, a variable and wide-spread species of West- 
ern North America, sg a forms of which have ‘tks described as distinct. 
The only one which m haps claim specific recognition is our var. 
Feffreyt (P. Feffreyt, Mu urr.), habeus rized by its darker more finely cleft 
bark, glaucous branchlets, paler foliage, and much larger cones, with rather 
slender sharp recurved prickles and larger seeds; but it seems that inter- 
notice is var. scofpulorum, of the Rocky Mountains, with shorter and often 
binate leaves and smaller cones (see Engelm. in Fl. Calif. 2, p. 125). 
23. P. Canariensis, Ch. Smith, is perhaps more nearly related to P. 
Laricio epee to ponderosa. The articulation of the 4 involucral bracts is 
acurious feature which it has in common with our P. resinosa (see p. 168). 
24. P. Chihuahuana, Engelm., first described from the mountains of 
Chihuahua, but now repeatedly found in wai is well distinguished 
from all its relatives by its deciduous sheat 
25. P. Laricio, Poir. Strengthening peti avonnd. ducts and in bundles 
all around leaf; the ipicsl form has slender leaves and is tender in culti- 
ar. Mo 
leaf, and is more hardy than the species. Var. Austriaca or nigra is per- 
fectly hardy; it has the stoutest ehank of all the forms, with abundant 
strengthening cells. A specimen in Herb. Kew, Birmah, Griffi 4993» 
may belong here, thus a the range of the species far into Asia. 
