Pinus L.

7. Pinus L. View in CoL 2

Evergreen trees or shrubs with regularly whorled branches. Twigs of two kinds: long shoots bearing scale-like leaves; and deciduous short shoots bearing acicular leaves in clusters of 2—5(—8). Resin-canals 2 or more, varying in position. Male flowers catkin-like, clustered at the base of the young twigs. Cones ripening in the second or third year, eventually falling in their entirety, cylindrical to ovoid; ovuliferous scales woody; bracts minute; the exposed part of the scales (apophysis) with a prominent protuberance (umbo), usually ending in a spine or prickle.

Literature: H. Gaussen, Les Gymnospermes, Fase, vi, ch. xi, Pinus (1960). J. Klika et al., Jehlicnaté. Praha, 1953.

1 Leaves in groups of 5

2 Seedwinged; leaf with2 -4marginalresin-canals

3 Young shoots with fine, reddish-brown hairs; apophysis not swollen 20. strobus 3 Young shoots glabrous or glabrescent; apophysis swollen

4 Leaves rigid, directed forwards to apex of branches; cone

8-15 cm, curved 19. peuce 4 Leaves not rigid, pendulous; cone 15-25 cm, straight

18. wallichiana 2 Seedsnot winged; leaf with2 -3medianresin-canals

5 Bud-scales shiny; cones more than 1 | times as long as wide; seeds with fragile husk 17. sibirica 5 Bud-scales dull; cones less than 1 | times as long as wide; seeds with hard husk 16. cembra 1 Leaves in groups of 2 or 3

6 Leavesin groups of 3, rarelymixedwithsomein pairs

7 Winter buds cylindrical, resinous; leaves stout; umbo with strong, persistent mucro 5. ponderosa 7 Winter buds ovoid, not resinous; leaves slender; umbo with small caducous mucro, or not mucronate

8 Leaves not more than 150 mm; bud-scales closely appressed; cones 7-14 cm, strongly asymmetrical 3. radiata 8 Leaves 150-300 mm; bud-scales free, deflexed; cones 10-

20 cm, symmetrical 14. canariensis 6 Leaves in pairs

9 Seeds wingless or with wings less than 1 mm 15. pinea 9 Seeds with well-developed wings more than 1 mm

10 Twigs grey in first year

11 Leaves less than 1 mm wide; resin-canals submarginal,

rarely median 12. halepensis 11 Leaves more than 1 mm wide; resin-canals median

12 Twigs turning brown in second year; hypodermis of

2-3 layers; apophysis flat, with very short, acute mucro

11. heldreichii 12 Twigs remaining whitish-grey for 3 years; hypodermis of

3-5 layers; apophysis pyramidal, with recurved mucro

10. leucodermis 10 Twigs not grey in first year

13 Buds not resinous; scales recurved at apex

14 Resin-canals marginal or submarginal; cone 5-11 x

4 cm 13. brutia

14 Resin-canals median; cone 8-20 x 5-8 cm 2. pinaster 13 Buds resinous; scales not recurved at apex 15 Resin-canals median 16 Leaves 30-70x1 mm, strongly twisted; cone asymmetrical 1. contorta 16 Leaves usually more than 80 x 1-5 mm, not or scarcely twisted; cone ±symmetrical 6. nigra 15 Resin-canals marginal or submarginal 17 Cones strongly curved; leaves dark green 4. banksiana 17 Cones not curved; leaves bright green or glaucous

18 Leaves glaucous; cone dull, acute, pendent

7. sylvestris

18 Leaves bright green; cone shining, obtuse, patent

19 Erect tree up to 25 m; cone 5-7 cm; apophysis very prominent, recurved and hooked 9. uncinata

19 Shrub up to 3 m; cones 2-5 cm; apophysis flat or concavo-convex, not recurved and hooked 8. mugo