FLOWERS 



47 



filaments in the other. Pollination will be effected only when some 

 of the pollen from a low-placed anther reaches the stigma of a short- 

 styled flower, or when the pollen from a high anther is placed upon 

 a long-styled pistil. This can be effected easily by flying insects. 

 Flowers which have this peculiar condition are said to be dimorphic 

 (Greek = of two forms). There are, as in the case of the loosestrife, 

 trimorphic flowers having pistils and stamens of three lengths. 



Protection of Pollen. — Pollen, in order to be carried effectively by 

 the wind, insects, or other agencies, must be dry. In some flowers 

 the irregular form of the corolla protects the pollen from dampness. 

 Other flowers close up at night , as the morning glory and four o'clock. 

 Still others, as the bell flower, droop during a shower or at night. 



Pollen is also protected from insect visitors which would carry off 

 pollen but give the flower no return by cross-pollinating it. In some 

 flowers access of ants, plant lice, or other small crawling insects, to 

 the stamens is rendered difficult by 

 hairs which are developed upon the fila- 

 ments or on the corolla. Sometimes a 

 ring of sticky material is found making 

 a barrier around the peduncle under- 

 neath the flower. Many other adapta- 

 tions of this sort might be mentioned. 



Inflorescence. — Inflorescence is a term 

 given to a flower cluster. It refers to the posi- 

 tion of the flowers on the flower stalk. Sev- 

 eral types of inflorescence have already been 

 noticed. In the Sedum the inflorescence is 

 limited or the length determined because the 

 flowers come out on the ends of the main 

 flower stalk. Such a determinate inflores- 

 cence is named a cyme. 



In most flower clusters the inflorescence 

 is said to be indeterminate because the indi- 

 vidual flowers come out on the sides of the 

 main flower stalk. Hence the length of the 

 inflorescence cannot be determined. There 

 are several common forms of indeterminate 

 inflorescence. Among forms we are likely 

 to meet are : — 



Kaceme of moth mullein. 



