THE SPRING FLORA. 193 



The principal factors to be considered are sun- 

 shine, shade, relative humidity, temperature, and 

 soil conditions. Determine also the nature of the 

 soil as far as possible, taking into account the 

 water content, amount of humus, acidity, mineral 

 salts, etc. 



c. Structure and seasonal life of associated plants. 



(1) Are the plants inhabiting the area under considera- 



tion mesophytes, xerophytes, or hydrophytes? Are 

 they annuals, biennials, or perennials in habit ? 

 Have they any special adaptations which fit them 

 for life in the habitat under observation ? 



(2) What are the dominant species ? Can you determine 



why they are dominant? Is their dominance due 

 to structural adaptations of leaf, stem, or root ? 

 Is dominance due to vegetative or other means 

 of rapid propagation and dissemination ? Is it 

 due in any measure to a perennial or biennial 

 seasonal life? 



d. Summary. 



(1) Draw a chart to indicate the distribution and abun- 



dance of the three or four dominant species of the 

 area examined. This may be done by using circles, 

 squares, and triangles of different sizes to repre- 

 sent different species, or by using the initial letter 

 of each species to represent the position of the 

 species in the plotted area (see Fig. 288 of text). 



(2) List the species found, indicating whether they are 



annuals, biennials, or perennials. Indicate also 

 whether they are mesophytic, xerophytic, or 

 hydrophytic in habit. 



(3) Work out by means of outline diagrams the seasonal 



history of one or two dominant species of the habitat. 



