30 OUR NATIVE FERNS AND THEIR ALLIES. 



side), and may be examined with a strong lens. The three di- 

 visions are summed up as follows : 



"I. Vernation wholly straight. B. simplex Hitch. (Fig. 31). 



II. Vernation partly inclined in one or both portions. B. 

 lunaria Swz. (Fig. 32), B. boreale Milde, B. matricaricefolium 



A. Br. (Fig. 33), and B. ternatum Swz. (Fig. 34). 



III. Vernation wholly inclined, in the fertile frond recurved. 



B. lanceolatum Angs. (Fig. 35), and B. Virginianum Swz." 

 The special characters of each species will be found under 



the descriptions of the Botrychia later in this work. The cuts 

 will be valuable for reference, and will enable even beginners to 

 identify the species of this complicated genus with compara- 

 tively little difficulty. 



84. Fructification. In this order of 

 plants the fructification consists of sporangia, 

 which, unlike those of the true ferns, are not 

 reticulated, possess no trace of a ring, open by 

 a transverse slit, and are variously spiked and 

 panicled (Fig. 20). In the adder-tongues 

 (Ophioglossum) the sporangia are large, and 

 cohere in two ranks along the margins of a 

 single spike, opening transversely to discharge 

 their copious sulphur-yellow spores. In the 

 grape -ferns (Botrychiuwi) the sporangia are 

 FIG. 20. Enlarged globular and arranged in double rows along 

 SSJ* 1 * Q ternat r u y m the narrow segments, more or less in panicles. 

 Swz - In both genera the sporangia are not developed 



from the epidermal cells, but arise from a transformation of the 

 interior tissue of the leaf. This, with other characters as clear- 

 ly denned, serves to separate these anomalous plants from the 

 order FILICES. 



85. Germination. Among the OPHIOGLOSSACE^E, so far 

 as known, the prothallia are destitute of chlorophyll, develop 

 under ground, and are monoecious. In Botrychium lunaria 

 the prothallium is an ovoid mass of cellular tissue, light brown 

 without and yellowish white within. It produces a number of 

 antheridia and archegonia on the upper surface as well as the 

 lower, differing in a few minor points from the true ferns in the 

 method of their development. 



