CHAPTER XXII 



PTERIDOPHYTES 

 OPHIOGLOSSALES 



This order contains only one family, the Ophioglossaceae, with 

 three genera, Ophioglossum, Botrychium, and Helminthostachys. The 

 first two species are cosmopolitan but the third is Australasian. 

 Some regard this order as merely a family, Ophioglossaceae, belong- 

 ing to Filicales. 



Botrychium. Botrychium is the most available member of the 

 order. While widely distributed, the individual plants are not 

 numerous. 



Vegetative structures. The stem of Botrychium is erect and sub- 

 terranean. It has an endarch siphonostele with secondary growth. 

 Cut away the thick, fleshy root; cut the stem into pieces about 5 to 

 7 mm. in length, fix in formalin alcohol, and imbed in paraffin. 

 Even the older parts of old stems can be cut in paraffin if you are 

 sufficiently careful. Transverse sections from the base of the bud 

 down to the secondary wood will give a beautiful series in the develop- 

 ment of the stele. 



The roots, in all stages, cut easily in paraffin. The root-tips 

 afford an excellent example of development from an apical cell. 

 Fix in chromo-acetic acid. For imbedding in paraffin, older parts 

 of the root should be cut into pieces not more than 5 to 7 mm. in 

 length. Fix in formalin alcohol. Transverse sections show a good 

 example of exarch protostele and also of the radial arrangement of 

 xylem and phloem (Fig. 76). 



The bud is a very interesting object. The leaf is in its fourth 

 year when it appears above ground, and, consequently, the bud 

 contains young leaves of three successive seasons. Two of the three 

 show a differentiation into sterile and fertile portions. 



Sporangia. Buds of B. virginianum taken in September or 

 October show sporangia with well-marked sporogenous tissue. For 



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