72 MORPHOLOGY AND LIFE HISTORY 



tend clear to the midrib? Compare the basal 

 with the more distal clefts in this respect. 

 (/) Do the pinnae appear to be all of the same age? 

 If not, state reasons for considering some of 

 them younger than others. Find evidence in 

 your specimen of the method of formation of 

 the pinnae. Are they opposite or alternate? 



(g) Describe and compare the venation of the blade, 

 and of the individual pinnae. Describe any 

 constant relationship between the venation and 

 manner of branching of the blade. 



(ti) Do the smaller veins anastomose (i.e., have their 

 ends united so as to form a network), or are 

 their ends free? Compare the fern leaf in this 

 respect with the foliage-leaf of a seed-bearing 

 plant. 



(i) Describe the appearance of very young, unex- 

 panded leaves or portions of leaves. 



(k) On the ventral surface of some of the leaves find 

 the brownish fruit-dots, or son (sing, sorus). 

 Describe their location. Do you find them o 

 the midrib of the frond or on the individual 

 pinnae? Are they between the smaller veins or 

 on them? If the latter, on what part of the 

 vein? Is their position constant (i.e., always 

 the same) ? Are they located at the margin of 

 the frond or pinna, or back from the margin? 

 Describe their shape. 



(/) Do the sori occur on all the pinnae of a leaf? 

 On all the leaves? Compare several specimens 

 with reference to this point. 



(m) Observe, using hand lens if necessary, that the 

 sorus is composed of a group of small organs 

 (sporangia). What do sporangia produce? 



