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338 Structural and Physiological Botany. 
carpellary scales, each of which bears two winged ovules. These 
scales overtake in their growth the bracts which are situated between 
them, and which are arrested in their growth and become coriaceous 
or woody. The cedar of Lebanon, Cedrus Lzbanz, is of historic interest, - 
but has now nearly died out, and is related to the exotic Araucariez. | 
The best-known European representatives of the sub-order are the Scotch 
fir, Pinus sylvestris, the Spruce fir, Penus excelsa, the larch, Larix 
europea, {and the stone pine, /zzus Pinea.| ‘The various trees belonging 
to it are of the highest value for a great variety of purposes ; the wood 
being employed for fuel and for building purposes, for joining and. 
turning work, for the manufacture of musical instruments, &c. [and for 
the navy]. The wood of the root is lighter and is less used for fuel than 
that of the trunk, but is richer in resinous substances, and therefore — 
more serviceable for the production of tar. Pinus sylvestris, Pinea, 
nigricans, and Pinaster, all yield common turpentine, from which tur- 
pentine-oil, pine-resin, colophony, and pitch are obtained. Venetian 
turpentine is prepared from the larch. <Adzes balsamea and canadensis 
of North America yield Canada-balsam ; Dammara orientalis from the 
Moluccas, and LD. australis from New Zealand, the Dammar resin or 
kauri-gum. L2nzles succtnifer is one of the extinct sources of amber. 
The starchy and oily seeds of Pzzus Pinea and P. Cembra-are edible. 
Many of the resins and volatile oils are officinal. [Principal genera :— 
Araucaria, Dammara, Pinus, Larix, Cedrus, Picea, Abtes, Sequoza, 
Cryptomerta, Taxodium, Frenela, Callitris, Libocedrus, Thuja, rota, 
Cupressus, Funiperus, Taxus,+ Torreya, Phyllocladus, Salisburta, 
Cephalotaxus. | 
Order 3. GNETACE&. To this order belong only three genera, of 
remarkably different habit. The various species of Zphedra are shrubs 
destituie of foliage-leaves, with long slender cylindrical green-barked 
branches ; at the joints of the stem are two opposite minute leaves, 
which grow together into a bidentate sheath, and from their axils spring 
the lateral branches. In Gyvetum the leaves are also opposite on the 
jointed stem, but are stalked, and have a broad lanceolate lamina. 
Welwitschia mtrabilis, the only representative of the third genus, never 
has more than two leaves, but these are of immense size, and are, ap- 
parently, the cotyledons. 
Crass XIII. Monocotyledones. 
The embryo has only one cotyledon. The perianth is 
simple, or, when double, without distinction of calyx ands 
corolla, and the prevalent number of its pants is three or six. 
