ILLUSTRATED FLORA. 



Subkingdom PTERIDOPHYTA.* 



FERXS AND FKRX-AI.I.; 



Plants containing woody and vascular tissues in the stem ;md producing 

 spores asexually, which, on germination, develop small flat mostly urecn - 

 tures called prothallia (gametophyte). On these are borne the sexual repro- 

 ductive organs, the female known as archegones, the male as aiitheri<: 

 the fertilization of the oosphere of the archegone by spermato/oids produced in 

 the antherids, the asexual phase (sporophyte) of the plants is developed ; this 

 phase is represented by an ordinary fern, lycopod or horsetail. 



This subkingdom comprises about 4000 living species, of which more than three-fourth* 

 are confined to tropical regions. The number of extinct species known probably exceeds 

 those living. They appeared on the earth in the early part of the Palaeozoic Era, reached 

 their greatest abundance in Carboniferous Time, but have since been mainly replaced by 

 plants of higher organization, so that at present they form only about one-fiftieth of the 

 total flora. The time of year noted under each species indicates the season at which the 

 spores are mature. 



Family i. OPHIOGLOSSACEAE Presl, Pterid. 6. 1836. 



ADDER'S-TONGUE FAMILY. 



More or less succulent plants consisting of a stem and leaf nmwin. 

 fleshy root. Sporanges formed of the interior tissues, naked, !*>nie in a 

 or panicle and opening at maturity by a transverse slit. Spor< 

 Prothallium subterranean, devoid of chlorophyll. 



Three genera, the following represented on both continents ; the thir.l, /A. i/A 

 native of southern Asia. 



Veins reticulate ; sporanges cohering in a distichous spike. 

 Veins free ; sporanges distinct, borne in spikes or panicles. 



i. OPHIOGLOSSUM L. Sp. PI. 1062. i 



Low plants from a small fleshy rootstock, with slender fleshy rooU. the bod 

 following year formed at the side of the base of the stem. Leaves solitary, 

 stem, simple in our species. Spike terminal, formed of the two rows < 

 sporanges. Veins of the leaf reticulate. Spores copious, sulphur-yellow. 

 the Greek, signifying the tongue of a snake, in allusion to the narrow spike < 



About 10 species of wide geographic distribution. lk-side> the following, three other* are 

 found in the southern United States, one of them extending to Calif 



*Text contributed by Professor LUCIEN M. UNDERWOOD. 



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