. Morphology of spermatophytes. [Part I. Gymnosperms]. Gymnosperms; Plant morphology. CONIPBRALBS 61 discoid ones closely imbricated and appressed upon tlie axis (" concrescent"), as in many of the Cupresseae, to the charac- teristic free needles of the Abieteae, and the broad blades of certain Podocarpeae (Figs. 44^46, 53). In general the phyllo- taxy is spiral, but in the Cupresseae it is cyclic. The foliage. Pig. 45.—Phyllocladus spp.: A, branch with staminate strohili; a, ataminate strobilus; b and c, sporophylls from a; d, longitudinal section of ovulate strobilus ; «, mature ov
. Morphology of spermatophytes. [Part I. Gymnosperms]. Gymnosperms; Plant morphology. CONIPBRALBS 61 discoid ones closely imbricated and appressed upon tlie axis (" concrescent"), as in many of the Cupresseae, to the charac- teristic free needles of the Abieteae, and the broad blades of certain Podocarpeae (Figs. 44^46, 53). In general the phyllo- taxy is spiral, but in the Cupresseae it is cyclic. The foliage. Pig. 45.—Phyllocladus spp.: A, branch with staminate strohili; a, ataminate strobilus; b and c, sporophylls from a; d, longitudinal section of ovulate strobilus ; «, mature ovulate strobilus; /, longitudinal section of «; 5 and g, ovulate branches. A and a-d^ P, trichomanoides^ after Hooker ; e and /", P, rhomboidalis^ after Eichard ; B and g, P. glaum.—Entire plate from Engleb and Prantl's Nat. Pflanzenfara. leaves are very persistent, enduring from one to ten years, the basal growth permitting them to increase in size at base with the increase in the diameter of the axis. So far as recorded, the only Conifers with deciduous leaves are Larix, Taxodium distichum, and Glyptostrobus, a habit which seems to be a de- rived one, as in the juvenile forms of Larix the leaves persist through the winter. The histology of the foliage leaf reveals a very xerophytic structure, and argues for adaptation to extreme conditions. The epidermis consists of elongated, iiberlike cells, with strongly cutinized walls, the guard cells being deeply sunken. The rigidity is chiefly due to the hypodermal layers or masses of elongated sclerenchymatous cells. In case the leaf is flat the mesophyll differentiates into the palisade and spongy regions, but if it is acicular the mesophyll is uniform throughout; in any case there are curious platelike " infoldings " of the wall. In the acicular leaves there is a single central bundle region,. Please note that these images are extracted from scanned page images that may have been digitally enhanced for readabilit
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Keywords: ., bookauthorcoulterj, bookcentury1900, bookdecade1900, bookyear1901
