. A manual of botany. Botany. Fig. 880. Section tbrongli protbaUium, p p, and young fern plant. K, The latter attached to the former by the foot. a. Ai-chegcnia of the prothal- lium. h. Root hairs of same. Afcer Saclis. Pig. 881. clearly distinguishable, and the axis is either mono-, sohizo- or polystelic. The stele consists of xylem and phloem, in vascular bundles, with circumferential pericycle in most cases. There is often a very marked development of sclerenchyma either in bands or patches. The leaves range from very simple structures to others almost as well differentiated as the leaves o
. A manual of botany. Botany. Fig. 880. Section tbrongli protbaUium, p p, and young fern plant. K, The latter attached to the former by the foot. a. Ai-chegcnia of the prothal- lium. h. Root hairs of same. Afcer Saclis. Pig. 881. clearly distinguishable, and the axis is either mono-, sohizo- or polystelic. The stele consists of xylem and phloem, in vascular bundles, with circumferential pericycle in most cases. There is often a very marked development of sclerenchyma either in bands or patches. The leaves range from very simple structures to others almost as well differentiated as the leaves of Phanerogams ; but their mesophyll is not so well divided into palisade and spongy parenchyma, and the epidermal cells contain chloroplastids. The growth in length of the stem, root, and leaf is usually effected by the segmentation of apical cells. In some cases, instead of a single apical cell there is a group of them, especially in the higher forms, where we have indi- cated an approach to the Phanerogams. Growth in thickness of the axis rarely takes place ; there is, however, a modi- fied cambium in Isoetes and in some of the Ophioglossacece. Some of the fossil forms of this group showed con- siderable cambial activity, the axis be- coming of very considerable diameter. The secondary roots are not developed from the pericycle, but from the endodermis of the axis; in the horsetails from its. Fig. 881. Prothallium, p, p, Adianlum Capillus-Vfm'ri.^ seen from below, showing the I'ern-plaiit developed from the fertilised germ-cell of the archegonium. 6. First frond. «',' ?i>." Roots, h. Root hairs. After Please note that these images are extracted from scanned page images that may have been digitally enhanced for readability - coloration and appearance of these illustrations may not perfectly resemble the original Green, J. Reynolds (Joseph Reynolds), 1848-1914. London, J. & A. Churchill
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Keywords: ., bookcentury1800, bookdecade1890, booksubjectbotany, bookyear1895
