1348 



1817. Pinus palustris. 



Leaf with two fibro-vasculiir bundles (a) ; several in- 

 ternal resin-ducts (6) ; one layer of strengthening cells 

 ('•) beneath the epidermis and on the inner sld» (if the 

 libro- vascular bundles: 



1818. Pinus echinata. 

 Leaf with two fibro-vascular bundles (a) and several 

 parenchymatous resin -ducts (&); only one layer of 

 strengthening cells (c) beneath the epidermis; 

 (d) all around. 



Kky for Determining Pises Without Conbs (compare 

 Figs. 1815-1818). 

 A. Number of Jv€. 5, only occa- 

 sionally S or 4. 

 B. Sheaths deciduous: fibro- 

 vascular bundle 1. 

 c. Edges of Ivs. serralafe. 

 D. Length of Ivs. IK-S in. 

 E. Branchlets glabrous or 

 nearly so. 

 P. The Ivs. 6-8 in. long: 



branchlets glaucou.i. 1. ezcelsa 

 PF. The Ivs. S-5 in. lotto: 

 branchlets «<>t 

 glaucous. 

 G. Tree a rather dense 



pyramid 2. Fence 



GO. Tree an open pyra- 

 mid 3. Strobus 



EE. Branchlets densely 



brownish tomentose . . W. Cembra 

 XEE. Brajichlets pubescent 

 or puberulous. 

 F. Needles slender, 

 somewhat pendu- 

 lous, 4-6 in. long... il. Ayacahuite 

 FF. Needles stiff, 1%-^ in. 

 long. 



a. Back nf Ivs. with 

 fine white lines... 5. 

 GO. Back of Ivs. usu- 

 ally not lined. 

 H. Color of Ivs. blu- 

 ish or dark 



green 4. 



HH. Color of Ivs. 



bright green 9. 



DD. Length of Ivs. %-l% in.: 

 Ivs. usually twisted, 

 forming brush - like 

 tufts at the end of the 



branchlets 8. 



cc. Edges of Ivs. entire. 



D. Lvs. 1%S in. long 7. 



DD. Lvs. l-ia in. long 15. 



BB. Sheaths persistent: fibro- 

 vascular bundles S: lvs. 



8-12 in. long, rigid 16. 



A. Number of lvs. 3, or 4 or 1, only 

 occasionally g or 5. 

 B. Usually solitary, sometimes 



inS's 14. 



BB. [Tsually 4, sometimes S or 5..V2. 

 BBB. Usually S, occasionally 2. 

 c. Fibro -vascular bundle 1: 

 sheaths deciduous. 

 V. Ma rgin of lvs. entire: lvs. 



',-/'.; III. long 13. 



im, .Miinjni of lvs. serrulate: 



Im. 2-iin. long 11. 



cc. Fibro-vascular bundles £: 



sheaths persistent. 



D. Branchlets glaucous: lvs. 



bluish or grayish green. 



(See also No. 21.) 



E. Habit of lvs. slender, 



drooping 17. 



EE. Habit of lvs. straight, 



stiff. 



F. Buds very resinous: 



lvs. 6-12 in. long, 



dark bluish green. . .18. 



FT. Buds not or little 



resinous: lvs.5-8in. 



monticola 

 Koraiensis 



eduUs 

 Bungeana 



Iff, pc 



bluish 



green 1 



DD. Branchlets not glaucous: 

 lvs. dark yellow or 

 bright green. 

 E. Habit of lvs. slender, 

 drooping. 

 F. Besin- ducts inter- 

 nal 2 



TT. Besin- ducts paren- 

 chymatous: buds 



brown 2 



FFF. Besin -ducts periph- 

 eral: buds bright 



chestnut-brown 2 



EE. Habit of lvs. stiff. 

 F. Length of lvs. 6-12 in. 



palastris 



Canariensis 



longiMia 



