EXERCISE 99 

 REPRODUCTION AND DISPERSAL OF THE FERN 



Materials. Fern leaves with fruit dots on under side may be 

 secured either in the woods or in greenhouses. 



Directions for work. Study the arrangements of the fruit dots 

 on the different leaves available. This is one of the characters 

 that assist in distinguishing different species. Record in notes 

 or sketches the different plans of distribution found. Record 

 also the shape and attachment of the scale which covers the 

 fruit dots. 



Scrape off onto a glass slide the contents of one of the dots, 

 selecting one that has not yet turned brown. Examine with a 

 hand lens and microscope. The sporangia will be seen, and 

 possibly the spores may be seen within them. If a compound 

 microscope is used, crush some of the sporangia by pressure on 

 the cover glass and observe the spores. These are asexual spores. 



Study dispersal by the following method: Place a fern leaf 

 with almost ripe sporangia on a piece of white paper, fruiting 

 surface downward. Allow it to remain undisturbed for a day or 

 two. The drying of the sporangia will cause them to open and 

 shed their spores. Examine the paper for spores and for evi- 

 dence that they are forcibly discharged by the sporangia. What 

 would be the result as to dispersal of the spores if they were 

 similarly discharged from a leaf in position on the plant ? What 

 if the wind were blowing? 



Some of the spores may be scraped from the paper and placed 

 on a slide for examination with the microscope. 



Common ferns may be readily identified by reference to 

 proper books. 



References 



BERGEN and CALDWELL. Practical Botany, pp. 280-282. 

 BERGEN and CALDWELL. Introduction to Botany, pp. 273, 274. 



Book for Identification 



GRAY. New Manual of Botany, 7th edition. American Book 

 Company. 



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