Flowers and tJieir Parts 



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in Crassttla and Datura, the central or terminal bud opens 

 first, and later buds come from side branches below. This 

 type of flower cluster is known as a cyme, and the flower 

 arrangement is definite or determined ; that is, the first flower 

 determines that the stem shall extend no farther. It has a 

 definite length. It happens that flowers do not, as a rule, 

 follow strictly one or the other arrangement, but the definite 

 and indefinite are often mixed. The flower cluster of the 



Fig. 125. — Compound umbel of Bubon. (From Edmonds and Marloth's 

 ■' Elementary Botany for South Africa.") 



olive is a raceme, but the separate branches have the flowers 

 arranged in cymose clusters. In Leo7iotis each separate flower 

 cluster is definite, but the younger clusters are at the top. The 

 terminal umbels of Wild Carrot, which are the first to open, 

 are indefinite. Younger umbels tip the branches which come 

 from the axils of lower leaves, the youngest being lowermost 

 on the stem. 



Examine different flower clusters and make diagrams of the 

 anthotaxies. We have found that Nature does not do things 

 without reason. Be sure there is a good reason for the different 



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