THE PLANT GROUPS 81 



lateral branches, bright green in color. Motile, free- 

 swimmiug spores or zoospores are also formed in some 

 species as asexual bodies. 



a. Vegetative reproduction. Search for the club-shaped 



branches with a low power. How are they formed ? 

 How do they become free from the mother plant? 

 How would they grow into a new Vaucheria plant ? 

 Do you find free productive branches in your material? 



b. Asexual reproduction by zoospores. These are difficult 



to demonstrate in Vaucheria except in unusually 

 favorable material. Draw any stages of asexual repro- 

 duction which you have succeeded in demonstrating. 

 4. Life history. Write a graphical life history of Vaucheria 

 similar to that constructed for Spirogyra. In what 

 respect are the two life histories similar ? In what re- 

 spects different ? Which alga has the higher type of 

 reproductive process ? Explain. What is the function 

 of vegetative and asexual reproduction as contrasted 

 with sexual reproduction in a plant like Vaucheria ? 



(EDOGONIUM 



Habit. Study plants of (Edogonium and compare them 

 with ftpirogyra and Vaucheria as regards form and 

 structure. How do the cells differ in form and contents 

 from the other algte studied ? Draw a plant of (Edo- 

 gonium to illustrate its habit and cell structure. 

 Reproduction. Study plants in which the gametes are 



forming. 



a. Female gametangia and gametes. Observe one or two 

 stages in the formation of female gametes from single 

 cells of the filament as described in the text. How 

 is the female gamete formed ? What is its structure ? 



