346 PRACTICAL COURSE IN BOTANY 



sketch, labeling the primary branches of the frond, pinnce 

 (sing., pinna), the secondary ones, if any, pinnules, and the 

 common stalk that supports them, stipe. Note the color, 

 texture, and surface of the stipe. If any appendages are 

 present, such as hairs, chaff, or scales (in Pteris, nectar 

 glands), notice whether they are equally distributed. If not, 

 where are they most abundant ? 



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 Fig. 

 105. Do the stipes grow from a root or a rhizome? How 

 do you know? Do you find any remains of leafstalks of 

 previous years? How does the rootstock increase 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 bundles. Trace their course 

 through several internodes. Do they run straight, or do 

 they turn or bend in any way at the nodes ? If so, where 

 do they go? Do you see anything like roots? Where do 

 they originate ? Put one of them under the microscope and 

 find out whether they are roots or hairs. 



True roots are first developed in the pteridophytes. Since 

 those of the fern spring from an underground stem, to what 

 class of roots do they belong ? (83.) 



403. Minute study of a fern stem. Place a very thin 

 section of a fern rhizoma, or of the stipe of a frond, under 

 the microscope. Except in very young stems the vascular 

 bundles are arranged in a ring, or sometimes in two or 

 more rings (Fig. 492), with plates of strengthening tissue, 

 I, I, between the inner and outer rings. Notice the inner 

 epidermal layer of hard brown tissue, and within that, the 

 soft parenchyma, which fills the rest of the interior. Test 

 it with iodine and observe how rich in starch it is. If the 

 section of a petiole is under observation, the details will 

 be somewhat different ; would you expect to find as much 

 starch in the stipe as in the rootstock ? Why, or why not ? 



