. Carnegie Institution of Washington publication. 106 THE OPHIOGLOSSALES unequal dichotomy, like that which results in the Hist divisions of the primary leaves. In large plants the leaves may reach a length of 30 or 40 centimeters. The petiole is nearly cylindrical at its base, but higher up becomes slightly winged at the margins, these wings passing into the lamina. A section of the petiole taken a little way below the insertion of the sterile lamina shows that the peduncle of the sporangio- phore is recognizable for a long distance below the point at which it becomes free, its adaxial surfac
. Carnegie Institution of Washington publication. 106 THE OPHIOGLOSSALES unequal dichotomy, like that which results in the Hist divisions of the primary leaves. In large plants the leaves may reach a length of 30 or 40 centimeters. The petiole is nearly cylindrical at its base, but higher up becomes slightly winged at the margins, these wings passing into the lamina. A section of the petiole taken a little way below the insertion of the sterile lamina shows that the peduncle of the sporangio- phore is recognizable for a long distance below the point at which it becomes free, its adaxial surface projecting as a rounded ridge between the wings on the margin of the petiole (tig. 78, D). In texture the leaves are firmer and more leathery than in any of the other ()phioglossaceae, and in this respect, as well as in their venation, thev closely resemble such Marattiaceae as Dance a and Angiopteris. The sporangiophore is to some extent intermediate in character between that of Ophioglossum and Botrychtum. It is inserted near the junction of the lamina and petiole, but, as already stated, can be traced for some distance below the point where it joins the petiole. The fertile portion of the sporangiophore, which ma)- reach a length of nearly 10 centimeters, is composed of crowded, short branches, upon. Fig. 79. A. Rhi/.oine of Helminthosiachys. th, stipular sheath. B. Section of rhizome. The dark spots are tannin sacs. C. Tannin sacs from the rhizome. which are borne groups of nearly globular sporangia much like those of Botrychtum. 1 he ends of the branches which bear the sporangia may be expanded into small leaf- like organs which, under/exceptional conditions, look much like small leaves, upon which the individual sporangia are borne (see Bower 9, fig. 239). The stem in Helmtnthostachys almost always remains unbranched, except that there may be formed adventitious buds somewhat as in Botrychium. The origin of these buds, however, has not been investigated. The rhizo
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