92 A TEXT-BOOK OF BOTANY. 



(2) The TRUE FERNS include by far the largest number of 

 species which inhabit temperate regions. These vary consider- 

 ably in size, ranging from quite diminutive plants 5 to 12 cm. high, 

 as the slender Cliff Brake (Pellcea atropurpurea and the variety 



FlG. 55. Different types of Perns and fern allies. I, fertile and sterile leaves of slender 

 cliff brake (Pellaea Stelleri); 2, ebony spleen-wort (Asplenium platyneuron) ; 3, rhizome 

 with two leaves of the common polypody (Polypodium vulgare) ; 4, maiden-hair spleen- 

 wort (Asplenium trichomanes) ; 5, ternate grape-fern (Botrychium ternatum), showing the 

 tripinnate sterile leaf on the left and the upright sporophyll on the right; 6, walking fern 

 (Camptosorus rhizophyllus) showing a new plant developing from the tip of one of the leaves; 

 7, fertile and young sterile leaves of ostrich fern (Onoclea Struthiopteris). 



