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MANUAL OF POISONOUS PLANTS 



Osmunda. L. Flowering Fern 



Tall ferns growing in swamps or low ground. Fertile fronds much con- 

 tracted and bearing on the margins the short pedicelled, naked sporangia on 

 the margins of their radii like divisions without chlorphyll; sporangia thin, 

 reticulated, opening by a longitudinal cleft into two halves, with a few thick- 

 ened cells the rudiment of the ring. 



There are six species in the North temperate regions, three species com- 

 mon in the North, the Cinnamon Fern (O. cinnamomea), clothed with rusty 

 wool; the Royal Fern (O. regalis}, a smooth pale green fern, 2-5 feet high, 

 with 13-25 sterile pinnules; Clayton's Fern (O. Claytoniana), clothed with 

 loose wool, but soon smooth; pinnae oblong lanceolate; some of the middle 

 pinnae fertile. The O. regalis is used as a tonic and styptic. By some these 

 ferns are regarded as injurious to stock. 



EQUISETALES. Horsetails 



Rush-like perennial plants, epidermis impregnated with silica; creeping root- 

 stocks, stem generally hollow jointed, simple or branched, striated or grooved, 

 provided with a double series of cavities and usually a large central one, 

 branches verticillate ; leaves reduced to a sheath which is divided into teeth 

 corresponding to the principal ridges of the stem; stomata in furrows; 



Fig. 125. Formation of Archegonia of Osmunda. A. Early development seen from 

 the surface. B. The same in vertical section. C-E. Farther development. F. Opened 

 and closed neck. G. Neck in oblique section. /. Fertilization of the mature archegonium. 

 a. archegonium, h. neck of the same, c. central cell, e. egg, be. spermatozoids, lie. neck 

 canal cells. B-J x 240. A. greatly magnified. After Luerssen. 



