HOW A FERN FRUITS 237 



The frond is all of the fern which grows on one stem from the 

 rootstock. 



A sterile frond bears no fruit. 



A fertile frond bears the fern fruit which consists of spores. 



The blade is that portion which bears leaflets. 



The stipe is the stem or petiole. 



The rachis is the midrib and is a continuation of the stipe. 



The pinnule is a leaflet of the last division. 



The pinna is a chief division of the midrib or rachis, when the 

 fern is compound. 



The sort are the fruit dots. 



The indusium is the membrane covering the fruiting organs. 



The sporangia are tiny brown globules, and are the spore cases 

 in which the spores are developed. 



The spores make up the fine dust which comes from the spore- 

 cases. A spore in not a seed. A seed is developed by pollen and 

 an ovule. The spore is simply a specialized part of the fern leaf. 



It would be well to make a diagram on the blackboard of the 

 fern with its parts named, so that the pupils may consult it while 

 studying ferns. 



i. Fruiting pinnules of the maiden-hair fern, en- 

 larged. 2. Fruiting pinnule of the bracken, enlarged. 

 In both these species the spores are borne under the 

 recurved edges of the pinnules. 



How a Fern Fruits 



The Christmas fern may be taken as a type in describing the 

 fruiting organs. In studying a fertile frond of the Christmas 

 fern from above, we notice that about a dozen pairs of the pinnae 

 near the tip are narrowed and roughened and are more distinctly 



