224 



BOTANY. 



416. The True Ferns (Order 30, Filicbs) include very 

 nearly all the common fern-like plants of our woodlands 

 and hillsides. They are among the most beautiful of our 

 land-plants, and their leaves furnish examples of a graceful- 

 ness of bearing and outline scarcely excelled in the vege- 

 table kingdom. In temperate climates ferns are herbaceous, 

 but in the tropics many possess an erect perennial woody 

 stem which bears a crown of leaves upon its summit. 



417. The tissues of the True Ferns are well developed. 

 The epidermis resembles that of the flowering plants. 



-3> 



FiQ. 133.— Spore-case clusters (spore-dots, or sorl) of various Ferns. A, 

 round and naked (Polypodmm) ; B, round and covered (Aspidlum) ; C, 

 elongated and covered (Asplenium) ; D, elongated, and covered by fold- 

 ing of the leaf (Adian turn). All magnified. (The covering (i) is known as 

 the indusium.) 



Complicated fibro-vascular bundles run through the stems 

 and extend into the leaves, where they branch extensively, 

 forming the delicate veins which are so characteristic of 

 fern-leaves. 



418. The young leaves before expanding are coiled or 

 rolled, so that as they grow up and open they unroll from 

 below upwards (i.e., circinately). Upon the lower surface 

 of some of the leaves little clusters of club-shaped hairs 

 (trichomes) grow out, generally in connection with a fibro- 



