FERN PLANTS 



255 



Examine the mode of attachment of the stipes to their 

 underground axis. Break one away and examine the scar. 

 Compare with your 

 drawings of leaf scars 

 and with Figure 274. 

 Do the stipes grow 

 from a root or a 

 rhizoma ? How do 

 you know ? Do you 

 find any remains of 

 leafstalks of previous 

 years ? How does 

 the rootstock in- 

 crease in length ? 

 Measure some of 

 the internodes ; how 

 much did it increase 

 each year? Cut a 

 cross section and look 

 for the ends of the 

 fibrovascular bun- 



Trace their 



thrnno-h *PV 

 OUgn S6V- 



eral internodes. Do 



they run straight or 



do they turn or bend in any way at the nodes ? If 



where do they go ? 



361. Veining. Hold a pinna up to the light and ex- 

 amine the veining. Is it like any of the kinds described 

 in Sections 37-40 ? This forked venation is a very general 

 characteristic of the ferns. When the forks do not reticu- 

 late or intercross in any way, the veins are said to be free ; 

 are they free in your specimen, or reticulated ? 



362. Fructification. Examine the back of the frond; 

 what do you find there ? (Most ferns bear many sterile 

 fronds ; care must be taken to secure some fruiting ones.) 

 These dots are the son (sing. sorns\ or fruit clusters, and 



dles. 



480-484. A fern plant: 480, fronds and root- 

 stock; 481, fertile pinna: s, s, soii; 482, cross 

 section of a stipe, showing ends of the fibrovascular 

 bund , es; 4 8 3 , a cluster of sporangia, magnified; 

 484, a single sporangium still more magnified, 



sliedding its spores ' 



so, 



