CHAPTER XXIX. 

 QUILLWORTS (ISOETES). 



Exercise 56. 



294. The isoetes plant. — Sketch an entire plant. Only the leaves (resem- 

 bling " quills ") and the roots can be seen. Note the relation of the leaves, 

 how they overlap. Remove a few. Describe and sketch the form. Note 

 the thickened base, its shape like a spoon. 



Upon the inner side of the thickened base note the circular depression of 

 a different texture. This is the spore-case. Note the thin overlapping 

 membrane around the edge of the spore-case. Just above the sporangium 

 note the small appendage. Observe the thin outer wall of the spore-case ; 

 that through this in many cases the large spores can be seen in many of 

 the spore- cases, especially the outer ones.. 



Section a plant longitudinally, or examine one that has been split into 

 halves longitudinally, in order to see the attachment of the leaves, and to 

 see the short stem. Note here also the spores in the spore-cases ; also the 

 cross-strands of tissue dividing the spore-cases into chambers. 



Tease open several of the sporangia to expose the spores. Note the large 

 spores in some ; the small spores in others. 



Demonstration 42. 



295. Two kinds of spores. — Spores of each kind may be mounted in water 

 for demonstration. Let each pupil sketch and describe one of each kind. 

 It is an important thing for the student to know one of the fern-like plants 

 which bear the two kir.ds of spores, as it helps one to understand the two 

 different kinds of spores in the pines and flowering plants. 



296. Habit of isoetes. — The quillworts, as they are popularly 

 called, are very curious plants. They grow in wet marshy places. 

 They receive their name from the supposed resemblance of the 



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