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. X1.5. 



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 rhizome is rather fleshy in texture and 

 may reach a diameter of about a centimeter. Usually but one leaf is fully developed 

 at a time, but it is not uncommon to find two leaves produced the same season. 

 Farmer's description and figures of the structure of the terminal bud show that it is 

 essentially the same as we have found it to be in the younger plant, and, as has 

 already been pointed out, it shows strong resemblances to the terminal bud in 

 Botrychium lunaria. 



I he stomata (fig. 78, C) are confined to the lower surface of the leaf and are 

 surrounded by a series of concentrically placed cells like those around the stoma in 

 Ophioglossum pendulum. They an- much smaller in size, however, and in this 



