Gymnosperms : Coniferae : Anatomy of Foliage-Leaves. XV. 



A. Comparison of the Leaves of Pinus (sp.); type, P. sylveslris. 



I. Pinus Pinaster (= maritimd) ; 2-needled spur ; leaf large well-differentiated, 

 5-8 in.; stomatal lines 12-14 on A at side, 18 on convex side ; serrations 5 to 1 mm.: 

 clean semicircular outline to section. 2 mm. wide. Epidermal cells almost solid ; 

 Hypoderm 2-3 deep, thick-walled, interrupted at stomata ; guard-cells sunk at base 

 of cylindrical outer chamber (45 /x), blocked with exudation in old needles. Plicate 

 mesophyll 3 cells deep, palisade-like at surface ; good U-cells below stomata : Ducts 2, 

 lateral, of 3-5 (7-10) in Mesophyll, with one layer of fibrous-sheath, not very thickened : 

 two V.B., separate, well-marked rays; no central fibres; tannin-sacs over phloem, 

 with but slight thickening, as also over protoxylem. Transfusion-tracheides 3 deep 

 over phloem. Massive angles, 150 /x thick. The finest type of Pinus-leaf. 



II. P. radiata {== insignis) ; 3-needled spur (varying 2), spinous teeth of 

 margin 4-5 per mm. ; 4-5 in. long ; stomatal lines on 3 sides, 9-12 on convex outer, 

 and 4-5 on radial faces, latter at angle of 120 ; section 1-6 mm. broad; differentia- 

 tion much as preceding : Hypoderm 2-3 cells deep, interrupted at stomata ; plicate 

 mesophyll 3 deep; 2 V.B. separate, or nearly confluent; Resin-ducts 2, lateral, in 

 mesophyll (1 or wanting): Guard-cells sunk 30 /x, outer chamber broadly flask- 

 shaped (35 fx), with outer pore (10 fx). Plicate cells palisade-like. Central fibres at 

 base only; tannin-sacs over phloem: a small duct occasionally between xylems. 



III. P. excelsa ; 5-needled spur, leaves slender, 5-8 in. long ; marginal 

 serrations irregularly \ mm. apart ; triangular in section, -8 mm. wide : stomatal 

 lines 4-5 on radial faces only, wanting on outer side. Ducts 2 (13), peripheral, on 

 outer face, (exc. in mesophyll). Guard-cells sunk 20 ll only ; hypoderm 1-2 deep ; 

 plicate mesophyll 2 deep. Stele small and circular (-3 mm. diam.) with V.B. for the 

 most part undivided. Transfusion-tracheides few, around periphery : albumen-cells 

 distinct. P. Cembra closely similar. 



IV. Pinus monophylla ; exceptional one-needled spur; leaf 2 in. long, 

 cylindrical; section circular, 2 mm. diam.; stomatal lines about 24: ducts 2, lateral, 

 or 6-7 peripheral, spaced round hypoderm ; each with 2-3 layers of small sheathing 

 fibres. Plicate mesophyll 6 layers deep, smaller peripherally, with more marked 

 foldings : V.B. confluent laterally in one line ; fibres over phloem, with tannin-content 

 over xylem. Transfusion-tracheides 3 deep; parenchymatous cells of pericycle 

 particularly well marked. A very beautiful leaf. 



B. Comparison of leaves of other Abietineae. 



I. Cedus Deodara: Spur many-leaved (20-60); needle 30-60 mm., section 

 rhomboidal, 1 mm. diam. ; stomata on all sides ; guard-cells slightly sunk, lignified 

 and covered by subsidiary cells. Epidermis and hypoderm sclerosed ; Resin-ducts in 

 contact ; fibrous sheath slight. Plicate mesophyll 3 deep with palisade-effect. Stele 

 central, circular, -3 mm. diam., with endodermis ; 2 V.B. closely approximated, but 

 distinct. Transfusion-tracheides converging on fibres over phloem only, with simple 

 or bordered pits ; albumen-cells distinct. 



II. Larix europaea: Spurs many-leaved (20-60); needles 1 in. or more, 

 deciduous : section rhomboidal or bilateral. D.V. organization more marked in 

 primary members (of current year) : less sclerosed than preceding. Primary leaves 

 (2 in.) with palisade-effect, and stomata on both sides. Resin ducts 2, lateral. 

 Small circular stele, 300 /x diam., 2 V.B. closely confluent, few transfusion-tracheides, 

 reticulated. 



III. Picea excelsa : no spur-formation ; needles 1 in. or less ; more or less 

 lozenge-shaped in section owing to flattening in vertical plane, 1 mm. deep, and half 

 as wide : stomata on both sides ; guard-cells lignified, sunk 20 fx, under conspicuous 

 subsidiary cells : Sclerosed hypoderm, mesophyll with first trace of plication, no 

 palisade, minimum spaces ; ducts 2 lateral (1 or o) : small circular stele (-2 mm. diam.) ; 

 2 V.B. separated by one row parenchyma ; a few scl. fibres over phloem ; transfusion- 

 tracheides few, albumen-cells distinct. 



IV. Abies cephalonica : massive needles, 1 in. or more, no spur- formation ; 

 a generalized type; largest leaves extended horizontally, 2 mm. broad, groove on 

 upper surface, median ridge and 2 stomatal tracts on lower. Epidermis sclerosed, 



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