POLYPODIUM. 



The J^eaf is all of the plant that is seen while growing. 

 It is more than a mere leaf, since it bears the fruit as well 

 as the foliage. Being thus a combination 

 of stalk and leaf, it is called the frond 

 (Lat. frons, a leafy branch). It stands 

 inclined so as to present an upper and an 

 under surface, both being green. At the 

 base its stalk is called the stipe. Its mar- 

 gins are deeply cleft in numerous segments 

 termed pinna (wings). Hence the frond 

 is said to be pinnalifid or wing-cleft. 



The Veins or ribs demand a careful 

 study. There are three kinds. The mid- 

 vein is the largest ; it is the continuation 

 of the stipe from the base of the frond to 



PIG. UI . Polypddium vulgare : 1, a fruit-bearing vein ; 2, fruit-cluster ; 3, a side 

 view ; 4, a capsule open ; 5, a spore, greatly magnified. 



its end or apex : 3d, the veinlets branch from the midvein 

 and pass through the middle of each of the pinnae : 3d, the 

 veinulets branch from the veinlets, then divide or fork, and 



