Biological Papers. 289 



t)ther at right angles, two and two each way, as here shown, and cannot be 

 arranged in a serial line except by combination, such as: 



CLASS PTERIDINE^. 

 Subclasses. Leptosporangiata. Eusporangiata. 



HoMOSPORE^ Pteridales Ophioglossales, 



Heterospore^ Hydropteridales Isoetales. 



Order V. PTERIDALES (Filicales): The Ferns. 



(Homosporous Leptosporangiate Stereocaulones.) 



Sporophytes herbaceous, terrestrial, consisting of a firm, strong, vascu- 

 lar, creeping, hypogean stem (rhizome), from which arise several 

 large, erect, long-stemmed leaves (fronds) of various forms, coiled 

 in prefoliation, including one or more fertile ones (sporophores) 

 which bear asexual spores in great numbers, minute and all alike. 

 Laminae of sterile fronds usually green on both sides; fertile fronds 

 (sporophores) brown or brownish beneath. Sporangia (spore cases) 

 stalked, developed normally from single epidei'mal cells and borne 

 in clusters, called sori, along the veinlets or the margin, on the 

 under side of the leaves or their segments, sometimes with a delicate 

 membranous covering of special and various form called indusium. 

 Sporanges each provided with a strong, elastic, multicellular ring or 

 bar, which bursts on maturity of the spores and flies open, scatter- 

 ing the spores with considerable force. 



Gametophytes (oophores) in the form of minute, two-lobed, green, flat, 

 lichen-like expansions (prothallia) on the surface of the ground, 

 produced from the spores, and which bear on their under surface 

 the fruit-bearing organs, the antheridia and archegonia, both on 

 the same plant (monoecious). In the bottom of each archegonium 

 is a cellular sac containing a single ovum or large cell analogous 

 to the embryo sac (ovulary) and ovule of the seed-bearing plants. 

 The antheridia bear numerous multiciliated motile sperms, called 

 antherozoids, which are to reach and impregnate or fertilize the 

 ova in the archegonia. This process, which is one of the most im- 

 portant and necessary functions of life for the perpetuation of 

 species, is ordinarily not seen, and would be wholly unknown with- 

 out careful attentive observation and concentrated systematic 

 study (peeping behind the curtains of nature, as it were). The 

 oospore, when ripe, and conditions being favorable, may germinate 

 and develop into a sporophyte similar to the original ancestor, and 

 bear infinite numbers of nonsexual spores as before, thus complet- 

 ing the cycle of life. 



There is only one family in Kansas. 



Family 19. Folypodiace.e: Fern Family. 



133. Onoclea sensibilis L. Sensitive fern. Moist wooded banks 



along the Missouri river; infrequent. August. (A) 



134. Woodsia obtusa Torr. Blunt-lobed Woodsia. Rocks and 



northern slopes in woods, northeast Kansas, west to 

 Mitchell, south to Chautauqua; frequent. July. (A S U) 



135. Cystopteris fragilis Bernhardi. Brittle fern. Rocky woods 



and shaded banks, N. E. K. ; common. (A S U) 

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