146 Plants and their Ways in South Africa 



takes its name from the umbel or umbrella-like arrangement 

 of the flowers. Widely different families have this floral ar- 

 rangement — as the Pelargoniums and Erodiums of the family 

 GeraniacecE, many of the Amaryllidaceae or Belladonna family, 

 Microloma and Asclepias. 



In what is regarded as the true spike, raceme, capitulum, 

 and umbel, the younger flowers continue to open toward the 



Fig. 142. — Simple umbel of Nerine. 



The 



top or centre, which in the umbel corresponds to the top. 

 arrangement is indefinite or racemose. 



In Dianthus and other members of the Carnation family, 

 in Crassula 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 ar- 

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

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

 finite length. It happens that flowers do not always follow 



