i8 



PLANT BIOLOGY 



is, false annuals). Of such are lily, crocus, onion, potato, 

 bull nettle, and false indigo of the Southern states. 



True annuals reach old age the first year. Plants which 

 are normally perennial may become annual in a shorter- 

 season climate by being killed by frost, rather than by dying 

 naturally at the end of a season of growth. They are cli- 

 matic annuals. Such plants are called plur-annuals in the 

 short-season region. Many tropical perennials are plur- 







Fig. 13. — A Shrub or Bush. Dogwood osier. 



annuals when grown in the north, but they are treated as 

 true annuals because they ripen sufficient of their crop the 

 same season in which the seeds are sown to make them 

 worth cultivating, as tomato, red pepper, castor bean, 

 cotton. Name several vegetables that are planted in 

 gardens with the expectation that they will bear till frost 

 comes. 



Woody or ligneous plants are usually longer lived than 

 herbs. Those that remain low and produce several or 



