. The Eusporangiatae; the comparative morphology of the Ophioglossaceae and Marattiaceae. Ophioglossaceae; Marattiaceae. 158 THE MARATTIALES may usually be recognized without difficulty. This cell is usually quite deep and in all of the genera except Dancra has a truncate base in longitudinal section. In Dancea, however, the base is usually pointed and the cell closely resembles the corre- sponding cell in Botrychium, or the typical leptosporangiate ferns. The growth of the stem is usually rather slow and the leaves of the young plant are much crowded. In all of the forms examined, the tissue
. The Eusporangiatae; the comparative morphology of the Ophioglossaceae and Marattiaceae. Ophioglossaceae; Marattiaceae. 158 THE MARATTIALES may usually be recognized without difficulty. This cell is usually quite deep and in all of the genera except Dancra has a truncate base in longitudinal section. In Dancea, however, the base is usually pointed and the cell closely resembles the corre- sponding cell in Botrychium, or the typical leptosporangiate ferns. The growth of the stem is usually rather slow and the leaves of the young plant are much crowded. In all of the forms examined, the tissue derived from the inner cells of the segments and from the basal segments of the apical cell, where such segments were formed, remained as undifferentiated parenchyma and contributed only to the internal pith of the stem. Except that the leaves arise from the segments of the apical cell of the stem and all of their tissues are therefore indirectly derived from it, the stem apex of the young sporophyte takes no part at all in the development of the fibrovascular system of the stem, which, except for the bundles of the roots, is entirely composed of the leaf traces. The second leaf in Angiopteris usually shows a pretty well-defined but slender midvein, which may, however, fork at the apex, and this is true also of the third leaf. It is in the third leaf, both in Marattta and Angiopteris, that the characteristic stipules are first developed. These appear as lateral wing-shaped bodies close to the. Fig. 143. A. SecdoD of primary root of Danaa jamaicensis. X70. B. The vascular bundle. X175.' en, endodermis. C. Triarch bundle from a primary root of D. elliptka. base of the petiole, partially inclosing the next youngest leaf and the stem apex. The third leaf in Angiopteris and several others succeeding it assume a more and more pronounced lanceolate form with a prominent midrib and pinnately arranged lateral veins which usually fork once. The margin of the leaf is serrate. After severa
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