1002 The Trees of Great Britain and Ireland 



the normal spring shoot with long leaves and brown withered scale-leaves, by bearing 

 short leaves with green scale-leaves. In this exceptional case, which is, however, 

 common in certain species, the buds and cones are said to be pseudo-lateral. 



Buds, varying in the different species in shape and in the characters of their 

 spirally imbricated scales, which are united together by their fringed margins 

 or matted hairs, or are embedded in resin, their tips being erect, spreading, or 

 reflexed. The buds are compound ; their outer scales empty and persistent at 

 the base of the shoot, when the bud unfolds ; their inner scales enclosing minute 

 buds, which develop into the short shoots and adult foliage (and when flower- 

 bearing, into the staminate flowers as well). These inner scales persist on the 

 developed branchlets as scale-leaves. 



Leaves of three kinds : (a) Primordial leaves, borne on seedling plants, solitary, 

 spirally arranged, spreading, linear-lanceolate, keeled on both surfaces, serrulate. 

 (6) Scale -leaves, containing in their axils the short shoots and adult leaves, 

 triangular-lanceolate, entire or fringed in margin, usually ' quickly deciduous in part, 

 their basal portion only persisting, (c) Adult leaves, needle-like, persistent two to 

 twenty years, in clusters of one to five (rarely six or seven), at the apex of the short shoot, 

 serrulate or entire in margin ; section 2 plano-convex in two-leaved species, triangular 

 in three- to five-leaved species ; fibro-vascular bundle branched or simple ; resin- 

 canals, two to twelve, marginal or median. The sheath at the base of each cluster, 

 formed by the scales of the minute buds, is either quickly and entirely deciduous or 

 persistent ; in the latter case usually becoming, with age, shortened, blackened, and 

 lacerated, but in certain species dividing into segments, which become reflexed and 

 surround the base of the leaf-bundle as a rosette. 



Flowers monoecious. Staminate flowers, 8 clustered in a head or spike at the base 

 of the current year's shoot, ovoid or cylindrical, surrounded at the base by an 

 involucre of scale-like bracts, composed of numerous imbricated sessile two-celled 

 anthers ; connective crest-like, nearly orbicular ; pollen-grains with two lateral air- 

 vesicles. Pistillate flowers or young cones, sub-terminal or lateral, solitary or in 

 clusters, surrounded at the base by sterile bracts ; composed of two series of scales, 

 minute carpels becoming obsolete in the ripe cone, and large ovuliferous scales, 

 each of the latter bearing two pendulous ovules. Pollination occurs in the first year, 

 when the scales open to receive the pollen, closing immediately afterwards ; but 

 fertilisation, the arrival of the pollen-tube at the embryo-sac, does not occur till May 

 or June in the second year ; in consequence the cone remains small in the first year, 

 and increases only in size in the second year. 



Fruit a woody cone, 4 ripening in nearly all the species 6 at the end of the second 



1 In the species with leaves densely crowded on the branchlets, the scale-leaves persist during the first year. 



1 In P. monophylla, the section of the solitary leaf is terete. 



* Shaw, Pines of Mexico, I (1909), points out that in the Soft Pines the buds enclosing the staminate flowers are not 

 sufficiently advanced at the end of the growing season to be distinguishable ; but in the Hard Pines they are recognisable by 

 their larger size. In the latter, the young staminate flowers are either (a) enclosed in the general outline of the bud, or (*) 

 they form about the nodes of the bud characteristic enlargements, which are constant for each species. 



4 The subterminal, lateral, or pseudo-lateral position of the cone referred to in descriptions of species is, as already defined 

 above, that of the young cone in the first year. 



6 In P. Pinea, P. Uiophylla, and P. chihuahtiana the cones take three years to ripen ; and in these the umbo of the scale 

 shows separate growths of the first and second years. 



