. Text-book of botany, morphological and physiological. Botany. '5* MORPHOLOGY OF MEMBERS. (a) The conceptions of Stem, Leaf, Root, Trichome, as at present employed in botany, result from the examination of highly developed plants, the different members of which actually present considerable diversities, or display considerable differentiation ; but if the attempt is made to apply these conceptions in the same manner to the less differentiated Hepaticae, Algae, Lichens and Fungi, many difficulties arise, depending principally on the fact that the members of the thallome sometimes display strik
. Text-book of botany, morphological and physiological. Botany. '5* MORPHOLOGY OF MEMBERS. (a) The conceptions of Stem, Leaf, Root, Trichome, as at present employed in botany, result from the examination of highly developed plants, the different members of which actually present considerable diversities, or display considerable differentiation ; but if the attempt is made to apply these conceptions in the same manner to the less differentiated Hepaticae, Algae, Lichens and Fungi, many difficulties arise, depending principally on the fact that the members of the thallome sometimes display striking resemblances to leaves, hairs, stems, and even roots, while wanting others of their characteristics. Transitions occur from the members of Thallophytes which are but slightly differen- tiated morphologically to the highly differentiated members of Cormophytes. In the members which we term stem, leaf, root, hair, it is clear that those differences are only augmented which also occur, though in a lesser degree, in the more homoge- neous ramifications of the thallome, especially of the higher Algae; absolute distinctions between thallomes and leaf-bearing axes are not to be found. It is therefore a matter of convenience where the boundary-line is FIG. 115.—Longitudinal section through the apical region of three primary shoots of Charafragilis; /the apical cell, in •which segments are formed by septa; each segment being further divided by a curved septum into a lower cell which does not further divide and which developes into an internode g g" g"', and an upper cell which produces a node m m' and the leaves. Each node cell produces a whorl of leaves of different ages. (For a more exact description, see Book II, Characeae.) t (b) The expressions Thallome, Caulome, Phyllome, Trichome, Root, designate, as has been said, general ideas, from the definition of which are eliminated all those properties of the members which adapt them only for definite functions,
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Keywords: ., bookcentury1800, bookdecade1880, booksubjectbotany, bookyear1882
