PLANT ORGANS AND ORGANISMS 179 



these are generally developed on the same stem. Example: 

 Periwinkle. 



Raceme, or simple flower-cluster in which the flowers on pedicels 

 of nearly equal length are arranged along an axis. Examples: 

 Convallaria, Cimicifuga, and Currant. 



Corymb, a short, broad cluster, differing from the raceme mainly in 

 its shorter axis and longer lower pedicels, which give the cluster a 

 flat appearance by bringing the individual florets to nearly the same 

 level. Example: Cherry. 



Umbel, which resembles the raceme, but has a very short axis, and 

 the nearly equal pedicels radiate from it like the rays of an umbrella. 

 Many examples of this mode of inflorescence are seen in the family 

 Umbellifera, as indicated by the name, including Anis~, Fennel and 

 other drug-yielding official plants. 



A Spike is a cluster of flowers, sessile or nearly so, borne on an 

 elongated axis. The Mullein and common Plantain afford good 

 illustrations. 



The Catkin or Ament resembles the Spike, but differs in that it 

 has scaly instead of herbaceous bracts, as the staminate flowers of the 

 Oak, Hazel, Willow, Comptonia, etc. 



The Head or Capitulum is like a spike, except that it has the rachis 

 shortened, so as to form a compact cluster of sessile flowers , ak in the 

 Dandelion, Marigold, Clover, and Burdock. 



The Strobile is a compact flower cluster with large scales concealing 

 the flowers, as the inflorescence of the Hop. 



The Spadix is a thick, fleshy rachis with flowers closely sessile or 

 embedded on it, usually with a spathe or sheathing bract. Example : 

 Calla, Acorus Calamus, Arum triphyllum. 



The compound raceme, particularly if irregularly compounded, is 

 called a panicle. Ex. Hagenia abyssinica. 



Determinate Inflorescences. Determinate Anthotaxy is one in. 

 which the first flower that opens is the terminal one on the axis, the 

 other appearing in succession from apex to base or from center to 

 margin. The principal varieties are: 



The Solitary Determinate, in which there is a single flower borne 

 on the scape, as in the Anemone, or Windflower, and Hydrastis. 



The Cyme, a flower cluster resembling a corymb, except that the 



