CHAPTER IX. 



CYSTOPTERIS, Bemhardi. 

 (Cys-top'-ter-is.) 

 Bladder Fern. 



HE name of this small genus is derived from kystis, a bladder, 

 and a Fern, evidently in allusion to the nature of the 



indusium (covering) of each spore mass being inflated like 

 a bladder. In Hooker and Baker's "Synopsis Filicum " 

 Cystopteris forms Genus 19, and it is closely allied to Woodsia 

 and Microlepia. It is composed entirely of elegant and somewhat fragile Uttle 

 Ferns, and has its headquarters in the Temperate Zone of both hemispheres. 

 All the species have their fronds twice or three times divided, of thin texture, 

 and with veins free. The distinguishing characters of the genus, however, 

 reside in each sorus (spore mass), of a roundish form, being placed on the 

 back of the veins and provided with a nearly globular involucre of a mem- 

 branous (thin and more or less transparent) nature, which is inserted by its 

 broad base under the sorus, and at first covers it hke a hood. 



Culture. 



Notwithstanding its being small, this genus, which is composed of only 

 four species and a few varieties, is nevertheless very interesting, inasmuch as, 

 with the exception of the essentially North American C. hiilbifera^ all others 

 are indigenous to this country and well adapted for planting in the outdoor 

 Fernery, where shady and well-drained spots should be selected for them, 



