1348 



PINUS 



PINTJS 



^ C 



o. 



1817. Pinus palustris. 



Leaf with two fibre- vascular bundles (a); several in- 

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

 (c) beneath the epidermis and on the inner sid of the 

 nbro-vascular bundles ; stomata (d) all around. 



1818. Pinus echinata. 



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

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

 strengthening cells (c) beneath the epidermis; stomata 

 (d) all around. 



KEY FOR DETERMINING PINES WITHOUT CONE-S (compare 



Figs. 1815-1818). 



A. Number of Ivs. 5, only occa- 

 sionally 8 or 4. 



B. Sheaths deciduous: fibro- 

 vascular bundle 1. 

 C. Edges of Ivs. serrulate. 

 D. Length of Ivs. IV^-S in. 

 E. Branchlets glabrous or 



nearly so. 

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



branch-lets glaucous. 1. excelsa 

 FP. The Ivs. 3-5 in. long: 

 bran chl et s not 

 glaucous. 

 Q. Tree a rather dense 



pyramid 2. Peuce 



GG. Tree an oipen pyra- 

 mid 3. Strobus 



EE. Branch le ts densely 



brownish tomentose . . 10. Cembra 

 BEE. Sranchlets pubescent 



or pubemlous. 

 F. Ne edles slender, 

 somewhat pendu- 

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

 FF. Needles stiff, 1V^ in. 

 long. 



G. Sack of Ivs. with 



fine white lines... 5. Lambertiana 

 GG. Back of Ivs. us^^- 



ally not lined. 

 H. Color of Ivs. blu- 

 ish or dark 



green 4. monticola 



HH. Color of Ivs . 



bright green 9. Koraiensis 



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

 Ivs. iisually twisted, 

 forming brlish - like 

 tufts at the end of the 



branchlels 8. parviflora 



CO. Edges of Ivs. entire. 



D. Lvs. l%-8 in. long 7. flexilis 



DD. Lvs. 1-lVz in. long 15. Balfouriana 



BB. Sheaths persistent: fibro- 

 vascular bundles 2: Ivs. 



8-12 in. long, rigid 16. Torreyana 



AA. Number of Ivs. 8, or 4 or 1, only 



occasionally 2 or 5. 

 B. Usually solitary, sometimes 



in 2's 14. monophylla 



BB. Usually 4, sometimes 8 or 5.. 12. Parryana 

 BBB. Usually 8, occasionally 2. 

 c. Fibro -vascular biindle 1: 



sheaths deciduous. 

 D V Margin of Ivs. entire: Ivs. 



%-iy z in. long 13. edulis 



DD. Margin of Ivs. serrulate: 



Ivs. 2-4 in. long 11. Bungeana 



cc. Fibro-vascular bundles 2: 



sheaths persistent. 

 D. Branchlets glaucous: Ivs. 

 bluish or grayish green. 

 (See also No. 21.) 

 E. Habit of Ivs. slender, 



drooping 17. Sabiniana 



EE. Habit of Ivs. straight, 



stiff. 



p. Buds very resinous: 

 Ivs. 6-12 in. long, 

 dark bluish green.. .18. Ooulteri 

 FF. Buds not or little 

 resinous: lvs.5-8in. 

 long , pale bluish 



green 19. Jeffreyi 



DD. Branchlets not glaucous: 

 Ivs. dark yellow or 

 bright green. 

 E. Habit of Ivs. slender, 



drooping. 



p. Mesin - ducts inter- 

 nal 23. palustris 



PF. Jfesin - ducts paren- 

 chymatous: buds 



brown 24. Canariensik 



FFF. Kesin - ducts periph- 

 eral: biids bright 



chestnut-brown 25. longifolia 



EE. Habit of Ivs. stiff. 

 p. Length of Ivs. 6-12 in. 



