Flowerless-Plant Study 



697 



Diagram of the interrupted 

 fern, showing the three 

 pairs of fruiting pinna, 

 and a part of one of these 

 enlarged. This fern often 

 has fronds four or five 

 feet high. 



interrupted fern has, at about the middle of its frond, three pinnae on each 

 side, fitted for spore-bearing, the pinnules being changed into globular 

 cups filled with spore-cases. 



While not absolutely necessary, it is highly de- 

 sirable that each member of the class should look 

 at a fruit-dot of some fern through a three- 

 quarters objective of a compound microscope, 

 and then examine the spore-cases and the spores 

 through a one-sixth objective. It must be 

 remembered that this lesson is for advanced 

 grades, and is a preparation for systematic 

 scientific work. If a microscope is not available, 

 the work may be done with a hand lens aided by 

 pictures. 



Observations i. Take a fern that is in fruit ; 

 lay it on a sheet of white paper and leave it thus 

 for a day or two, where it will not be disturbed 

 and where there is no draught; then take it up 

 carefully ; the form of the fern will be outlined in 

 dust. What is this dust? 



2. What conditions must the spores have in 

 order to grow? What do they grow into? (See 

 First Studies of Plant Life by Atkinson, p. 207). 



3. Look at a ripe fruit-dot on the back of a 

 fern leaf and see where the spores come from. Can 

 you see with a lens many little, brown globules? 



Can you see that some of them are torn open ? These are the spore-cases, 

 called sporangia, each globule being packed with spores. Can you see 

 how the sporangia are fastened to the leaf by little stems? 



4. Almost all our common wood ferns have the spore-cases protected 

 by a thin membrane, the spore-blanket, when very young; this little 

 membrane is called the indusium, and it is of different shape in those ferns 

 which do not have the same sirname, or generic name. Study as many 

 kinds of wood ferns as you can find. If the blanket, or indusium, is 

 circular with a dent at the center where it is fastened to the leaf, and the 

 spore-cases push out around the margin, it is a Christmas fern; if horseshoe- 

 shaped, it is one of the wood ferns; if oblong, in rows on each side of the 

 midrib, it is a chain fern; but if oblong and at an angle to the midrib, it is a 

 spleenwort; if it is ocket-shaped and opening at one side, it is a 

 bladder fern; if it is cup-shapecl, it is a boulder fern; if it breaks open and 

 lays back in star shape, it is a woodsia; if the edge of the fern leaf is folded 

 over all along its margin to protect the spore-cases, it is a bracken; if the 

 tips of the scallops of the leaf be delicately folded over to make a spore 

 blanket, it is the maidenhair. 



5. If you know of swampy land where there are many tall brakes, look 

 for a kind that has some of its pinnae withered and brown. Examine 

 these withered pinnae, and you will see that they are not withered at all 

 but are changed into little cups to hold spore-cases. This is the inter- 

 rupted fern. The flowering fern has the pinnae at its tip changed into cups 

 for spore-cases. The cinnamon fern, which grows in swampy places, has 

 whole fronds which are cinnamon -colored and look withered, but which 

 bear the spores. The ostrich fern, which has fronds which look like mag- 



