. Le Eusporangiatae ; la morphologie comparative des Ophioglossaceae et Marattiaceae. Ophioglossaceae ; Marattiaceae. 50 L'être OPHIOGLOSSALES aucune trace de procambium intérieur de la feuille, des traces dans la région apicale de la tige elle-même. Fig. 40 montre un sporophyte qui a été coupé à angle droit par rapport à la racine primaire, qui dans ce cas a eu un paquet. triarch Près de sa base les trois masses de xylème augmentent en taille et forme un anneau presque complète des tissus de trachée, qui plus haut se poursuit dans les traces foliaires. La troisième feuille a déjà commencé à se former, mais est encore très petit. Ci-dessous, cependant

• Contributeur: The Book Worm / Alamy Banque D'Images
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. The Eusporangiatae; the comparative morphology of the Ophioglossaceae and Marattiaceae. Ophioglossaceae; Marattiaceae. 50 THE OPHIOGLOSSALES being no trace of procambium inside of the leaf traces in the apical region of the stem itself. Fig. 40 shows a sporophyte which was cut at right angles to the primary root, which in this case had a triarch bundle. Near its base the three xylem masses increase in size and form a nearly complete ring of tracheary tissue, which higher up is continued into the leaf traces. The third leaf has already begun to form, but is still very small. Below it, however, can be clearly seen the beginning of its large leaf trace, which can be followed downward to its junction with the second root, which is now just about ready to emerge. The stele of the second root is con- nected with the central cylinder of the axis near its junction with this third leaf trace. The stem apex occupies a very small area, crowded between the base of the second and third leaves. Its deep, narrow, apical cell is not as conspicuous as is often the case.. Fig. 41. A-F. six of a series of horizontal sections of a young sporophyte of Botrychium virginianum. X75. B passes through stem apex, sty which is shown more enlarged in G; r^, second root; /^, second leaf. A similar sporophyte is shown in cross-section in fig. 41. This was cut in the plane of the first root, which makes a sharp angle with the base of the cotyledon. The thick stele of the root is much expanded where it joins the leaf traces to form the beginning of the tubular stele of the axis, and at the point of junction there is a large nearly solid mass of short, irregularly disposed, reticulate tracheids. This young sporophyte was evidently the further development of an embryo of the type shown in fig. 35, A. The trace of the cotyledon makes a right angle with the stele of the root and on the side opposite to its junction with the stele of the root there can be seen the trace belonging to the second leaf, w

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