714 The Trees of Great Britain and Ireland 



when situated in the substance of the leaf about equidistant between its upper and 

 lower surfaces, or marginal or sub-epidermal, when placed in the lower part of the 

 leaf close to the epidermis; fibro-vascular bundle simple in some species, divided 

 into two parts in other species. 



Flowers moncecious, the two sexes on separate branchlets ; male flowers usually 

 abundant and on the lower side of the branchlets over the upper half of the tree ; 

 female cones on the upper side of the branchlets, usually only near the top of the 

 tree, but in some species borne all over the upper half of the tree. Staminate 

 flowers,^ solitary in the axils of the leaves of the preceding year's shoot ; stamens 

 spirally crowded on a central axis, anthers surmounted by a knob-like projection 

 and dehiscing transversely. Female cones,^ arising as short shoots, composed of 

 numerous imbricated fan-shaped ovuliferous scales, and an equal number of much 

 longer mucronate bracts ; ovules inverted, two on each scale. 



Mature cones erect on the branchlets, composed of closely imbricated woody 

 scales, more or less fan-shaped with short stalks. Bracts adnate to the outer surface 

 of the scales at the base ; either concealed between the scales or with their tips 

 exserted and then often reflexed over the margin of the scale next below ; dilated at 

 the apex, entire or two-lobed, prolonged into a triangular mucro. Seeds two on the 

 inner surface of each scale, winged, and with resin-vesicles. The cones ripen in one 

 season ; and the scales, bracts, and seeds fall away from the central spindle-like axis 

 of the cone, which persists for a long time on the tree. The seedling has four to ten 

 cotyledons, stomatiferous on their upper surface. 



The species of Abies are distinguishable from all other conifers by the circular 

 base of the leaves, which on falling leave circular scars on the branchlets. 



The species of Abies have been variously divided into sections by different 

 authors, but no satisfactory arrangement has yet been made out. Mayr proposed 

 three sections based on the colour of the cones ; but, as Sargent "^ points out, colour 

 is not a constant character in several species. The cones are of value in the dis- 

 crimination of the species, by taking into account their age, general appearance, and 

 characters as a whole ; but the scales are often very variable in shape in the same 

 species, and the bracts, while more constant in form, often show considerable 

 variation in their length. It is most convenient, in practice, especially as cones are 

 in most cases not available for examination, to group the species, according to the 

 characters of the buds, branchlets, and foliage, which are, as a rule, very constant in 

 the same species. HickeP proposes three sections, based on the characters of the 

 branchlets and buds ; but his division is artificial, as it separates species closely 

 allied by the characters of their cones. 



Some notes on the genus Abies, for which we are indebted to Mr. J. D, 

 Crozier, forester to H. R. Baird, Esq. of Durris, Kincardineshire, are inserted. 

 Mr. Crozier 's long experience in the east of Scotland gives a special value to his 

 opinion on their respective qualities for planting in Scotland, which our own 



1 Both the staminate flowers and the young female cones are surrounded at the base by involucres of bud-scales. 



2 Silva N. Amer. xii. 97, adnot. (1898). Sargent proposes three sections, based on the characters of the leaves. 



' Bull. Soc. Dendr. France, 1907, p. 11, 



