/•v.oir/.A'.s 161 



continues to i^row after the flowers are fertilised 

 until the round balloon-like ba<^ is formed in 

 which the fruit is enclosed. 



We will now examine tlie parts of a flower 

 separately, he^imu'n;^ u ith the cal\\. 



In the buttercup the cal\'\ consists of one whorl 

 ( >r rini; ot fi\ t- se|)als. 



In the straw tK-rr\- there are two whfirls of sepals, 

 aiifl in the cotton plant there are three whorls 

 forming;' its L;"reen cal}x. 



There are also variations in the mode c)f flower 

 exjiansion. 



As a pop|)\--bu(l opens it detaches its cal\\x 

 from the stem, and the sepals fall off the cal\-x is 

 therefore called caducous, a term which means 

 ready to droj) off;. 



Many flowers retain the calxx until the petals 

 wither and it falls off with them. It is then called 

 a deciduous cal\'x. 



Others a_L;ain ha\e a permanent cal\x, so that 

 when, as in the primrose, the corolla withers and 

 drops off, the sepals close over the seed-\essel and 

 protect it until the seeds arc matured ; this would 

 be called botanically a persistent cal\x. 



