. The classification of flowering plants. aves. The latter are, with rareexceptions, narrowly linear, extremely so in Pinus forming thecharacteristic needles. In some species of Podocarpus andDammara they are broad, and in the Gupressineae often smalland scale-like, and concrescent with the branch. They aresimple and entire and generally sessile, but sometimes, as inTaxus and Podocarpus (fig. 36, D), have a short stalk. Stipulesare never present. The narrow leaves have a single unbranchedmedian nerve; the broader, several parallel nerves. Afterfalling they may leave, as in Abies, a flat rounde
. The classification of flowering plants. aves. The latter are, with rareexceptions, narrowly linear, extremely so in Pinus forming thecharacteristic needles. In some species of Podocarpus andDammara they are broad, and in the Gupressineae often smalland scale-like, and concrescent with the branch. They aresimple and entire and generally sessile, but sometimes, as inTaxus and Podocarpus (fig. 36, D), have a short stalk. Stipulesare never present. The narrow leaves have a single unbranchedmedian nerve; the broader, several parallel nerves. Afterfalling they may leave, as in Abies, a flat rounded scar, or apersistent pulvinus, as in the Spruces and others, the formof which varies in different genera or species (fig. 18); it is athickened peg-like projection of the cortex of the stem. Theneedles of Pinus longifolia may be 16 inches long whilethe free points in Cypress are less than one line. Except in 80 FLOWERING PLANTS [CH. the Larch and Taxodium, where they are deciduous, the leavesare tough, more or less rigid, and Pulvini and leaf-scars. A. Abies pecthiata. C. Pseudotsuga Doufilasii. E. Cedrus Lihani (Cedar). B. Tsiiga canadensis. D. Picea excelsa (common Spruce). F. Larix europaea (Larch). G. Pseudolarix Kaempferi(After Eichler. From Veitch.) The leaves succeeding the cotyledons are generally speakingsimple and strikingly uniform throughout the Order whencontrasted with the mature and often highly specialised foliage-leaves. These primordial leaves, as they are called, arescattered and needle-like, and simpler in structure than theleaves on older shoots (fig. 19). Similar leaves sometimes appearat the base of older shoots or on the branches or stalks imme-diately below the cones ( Piniis excelsa). They may alsooccur universally on the adult plant as in the horticulturalgenus Retinospora which comprises species of Thuja, Cupressus(fig. 20), and Junijierus, in which the leaves have reverted to thejuvenile character; in other cases the juvenile occurs
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Keywords: ., bookcentury1900, bookdecade1900, booksubjectbotany, bookyear1904
