Gymnosperms : Coniferae Pinoideae Abietineae Pinus. VII. 



P I NUS (66-80), widely distributed in N. Hemisphere ; characteristic trees of 

 N. Temp, forest zone, with outlying strays in N. Africa, Canary Is., Burma, Philippines, 

 and Malay; only 1 sp. (P. Merkusii) crosses the equator. Finest types on the 

 Pacific Slope. Special centres of distribution : Western States of N. Amer. (21 sp.), 

 Eastern States (15), Mexican highlands (12), Mediterranean Region (5), Asiatic (14), 

 in foothills of Himalaya, to Japan. 



European forms deteriorate northwards (P. sylvestris), and on mountains 

 {P. montand)\ American forms deteriorate in N.W. {P. Banksiana, Jack Pine), 

 P. contorta from 100 ft. to a bush in Sphagnum bogs (Alaska), and coning at a few 

 inches (Californian wastes). Bush-forms also in Japan. The finest tree is P. Lam- 

 bertiana (Sugar Pine), 250 ft. or more recorded, with 100 ft. clear shaft, 6-12 ft. diam. 

 (Oregon and California). 



Spur-shoots: 5-3-2-leaved (1 in P. monophylla, and casual freaks, also 

 exceptionally 4-8). False whorls at end of annual shoot typical, an older phase 

 as additional ' whorls ', also cones (2-5 per annum), so called ' multinodal ' effect 

 in some sp. (P. radiata at Monterey, old Pitch- Pine, P. muricata, P. Banksiana, 

 P. Coulteri). Adventitious shoots from old trunks, with needles or juvenile leaves 

 {P. rigidd), in cracks of bark, and spurs may continue growth. Freely regenerating 

 from old stumps (P. rigida after forest fires), and from coppice-shoots {P. canariensis). 



Foliage-needles range to a foot long [P. palusiris), 16-18 in. (P. longi/olia). 

 Basal sheath of spur as much as an inch long ; persistent {P. Pined), or deciduous 

 {P. excelsd). Scales of the main axis decurrent, conspicuously so in P. Laricio, or not, 

 leaving a smooth stem (P. excelsd). 



Staminate flower, 1 inch to 2-3 in. (P. palusiris) ; dense inflorescence 

 (P. Pinaster). Pollen has been known to be drifted 400 miles. 



Ovulate flower, more distinctly stalked (P. excelsd) ; solitary in depauperated 

 P. sylvestris, P. montana ; in false whorls, clusters 2-5 {P. excelsd), 5-20 (P. Pinaster, 

 max. over 60) : f in. to 1 in. long ; cone-scales often more acuminate (pollen- 

 collecting brush). Younger cones erect over winter, sessile {P. austriacd), on stalks 

 1-2 in. (P. Strobus). Inverted cones on short stalks become markedly eccentric ; 

 scales on outer exposed side presenting exaggerated apophysial developments. 



Adult cone: longest P. Lambertiana, 21 in., heaviest P. Coulteri, 2-3 lb., and 

 a foot long; small in P. montana (ii in.): 2-season period typical, but 3 years' 

 growth in P. Pinea. Cones typically dropped after seed-shedding (P. Laricio), do not 

 open [P. Cembra); persist indefinitely, open, 10 years {P. radiata), closed, 30 years 

 (P. muricatd) ; opening after forest fires (P. Banksiana), buried by bark and even 

 submerged unopened (P. clausa). Such features express failure of original opening 

 and abscission mechanism. Axis breaks away above basal scales (P. palusiris) ; 

 basal scales reflex and shed (P. Pined), suggesting older mechanism of cone-scale 

 shedding. 



Seed up to 1 inch, with massive stony testa (P. Pinea) ; large seeds taken by 

 birds (Crossbill), squirrels, dormice (P. Cembra); edible (P. edulis, P. monophylla, 

 N. Amer., P. Gerardiana, Himalya); cultivated for food (P. Pinea, Medit. and S.Africa). 



Dispersal : Normally the cone-scales diverge by hygroscopic tensions on 

 desiccation, and the apophyses may strongly reflex (P. Coulteri) ; P. clausa commonly 

 fails to open, and P. Cembra has lost the mechanism. The seed-' wing', up to if in. 

 long, may be firmly attached (P. excelsd), or readily separates (P. Pinaster) from the 

 seed ; being asymmetrical, it produces a spinning rotation in the falling seeds, which 

 thus attain a limiting velocity of 2^-3 ft. per sec. after falling a few feet. In the case 

 of massive edible seeds the wing reduces to a functionless rudiment (P. Pined), and 

 is left on the scale, or represented by a ridge only (P. Cembra). Hence large seeds 

 with considerable food-storage are clearly secondary : the case of the small seed with 

 wing, wind-dispersed from an opening cone, as in more generalized Abietineae, is 

 undoubtedly the original condition, as the abscission of useless parts, as dead cones 

 and scales, is also primitive. 



Germination follows the normal course for oil-storage, and epigeal cotyledons, 

 with extrusion of the radicle at the micropylar end, elongation of the hypocotyl, and 

 withdrawal of the numerous linear cotyledons (to 13-15, P. Pined)', the latter 



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