ILLUSTRATED FLORA 



Phylum PTERIDOPHYTA/^ 



FERNS AND FERN-ALLIES. 



Terrestrial, epiphytic, or (rarely) aquatic plants, exhibiting a life cycle of two 

 well-marked phases, Sporophyte and Gametophyte, the so-called alternation of 

 generations. The former is the conspicuous one ; the plant, known as a fern or 

 fern ally, is usually differentiated into root, stem, and leaf, is provided with 

 vascular tissues, and bears spores asexually, these either alike (plants homos- 

 porous) or of two very unlike kinds called microspores and megaspores (plants 

 heterosporous). The germinating spore produces the Gametophyte. or minute, 

 inconspicuous sexual stage (prothallium). In the homosporous series the pro- 

 thallia are similar, but may be monoecious or dioecious ; in the heterosporous 

 series they are dioecious, the ones developing from the microspores producing 

 only male reproductive organs (antheridia), and those from the megaspores only 

 female reproductive organs (archegonia). Fertilization consists in the impregna- 

 tion of an egg cell or archegone by the coiled motile male element (spermatozoid). 

 The resulting growth is the Sporophyte, or conspicuous asexual stage. 



The pteridophytes first appeared in the early part of the Palaeozoic Era, and reached 

 the height of their development in Carboniferous Time, when they formed the dominating 

 t3'pe of vegetation. There are about 7,000 living species, of which more than three-fourths 

 are restricted to tropical regions. 



V 



Family 1. OPHIOGLOSSACEAE. 



Adder's-tongue Faimily. 



Sporophytes herbaceous, consisting of a short fleshy rhizome, bearing numer- 

 ous fibrous, usually fleshy roots and one or several leaves. Leaves (fronds) erect 

 (in our genera), not jointed, consisting of a simple to variously compound, sessile 

 or stalked sterile blade and, in the fertile leaves, a stalked sporebearing spike or 

 panicle (sporophyll), borne on a short to elongate common stalk. Sporangia 

 developed partly from subepidermal tissue (plants eusporangiate), naked, open- 

 ing by a transverse slit. Spores uniform (plants homosporous). yellowish. 

 Gametophytes (prothallia) hypogean. tuberlike, usually lacking chlorophyll and 

 associated with an endophytic mycorhiza. 



Five genera, the two following widely distributed and with numerotis species, the others monotypic. 



Sterile blade simple, with reticulate veins; sporangia united in two rows in a simple, slender, fleshy spike. 



1. Ophioglossum. 

 Sterile blade 1-4 times pinnately divided, with free veins; sporangia globose, all distinct, borne in a spike 

 or panicle. 2. Botrychium. 



1. OPHIOGLOSSUM [Tourn.] L. Sp. PI. 1062. 1753. 



Small herbaceous terrestrial plants. Rhizome short, hypogean, usually erect, terminat- 

 ing in the erect exposed bud for the following season. Leaves erect in vernation, 1-4, erect, 

 glabrous, fleshy, arising at the side of the apical bud ; common stalk short to elongate, 

 slender; sterile blade simple, sessile or short-stalked, linear-lanceolate to. ovate or reniform, 

 with reticulate venation, the areoles simple or with free and anastomosing veinlets; 

 sporophyll a simple slender long-stalked spike, the large globose sporangia marginal, 

 coalescent in 2 ranks, transversely dehiscent. [Name Greek, meaning the tongue of a snake, 

 alluding to the form of the narrow sporophyll.] 



About 45 species, of wide distribution in both hemispheres. Besides the following, 3 others occur 

 in the United States. Type species, OpIiiog!ossu»i viilgatinn L. 



Fronds usually solitary and much more than 10 cm. long; sterile blade obtuse or acutish, 1-5 cm. broad, 



translucent. 1. O. I'uUiatum. 



Fronds usually two and less than 10 cm. long; sterile blade acute, often apiculate, 5-10 mm. broad, 

 opaque. 2. O. calif ornicum. 



*Text (except Isoetaceae) contributed by William R. Maxon. 



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