INFLORESCENCE. 



77 



we may easily reduce all the various forms of inlloroscnce to 

 two primitive types, the determinate aiul indeterminate ar- 

 ranuomrnts. 



By determinate arrangement is meant that kind of intlorcs- 

 cenco which occurs when the |)rimary axis of the plant is 

 terminated by a tlower ; (meaning by the primary axis the 

 stem arising from the root.) 



The most simi)lo case ot' this kind is when the stem bears 

 a single tlower ; there being no secondary axes. 



When the secondary axes are develoj)ed, the lower being 

 proportionably longer, so that all rise to the same heiglit with 

 the central flower, we have a Corymb, (fig. 

 78 ;) but if neither the primary nor seconda- 

 ry axes lengthen but become crowded tojjether 

 around the same point, we have the Capita- 

 urn or head, as in the compound flowers, (fig, 

 ^79.) 



Each little flower comprising a capitulum is called ajloret. 

 The florets are often very diflerent in appearance, some con- 

 sisting of a ligulate or flattened limb arranged around the 

 circumtV'rence like the petals of other flowers, and are called 

 r^y florets as are seen in the sun flower, while the central are 

 u-^;ially tubular and unconspicuous and are called disk florets. 

 The ray and disk florets often difler in respect to the organs 

 they contain. Sometimes tiiey are both perfect, that is, both 

 containing stamens and pistils, when they are said to be 

 homoaamous ; at others the ray florets may be destitute of 

 either stamens or pistils, or contain pistils only, and tlie disk 

 contain only stamens ; in any of these cases the capitulum is 

 said to be hcierogamous. 



But if like the capit- 

 ulum in other respects 

 the axes are lengthened 

 in proportion to the 

 distance from the cen- 

 ter, we have the umhel, 

 (fig. 80,) in whicli the 

 pedicels all originate 

 from the same point ; 

 and if the second axes develop tertiary 

 axes in the samemmner as the primary develop tlie secondary, 

 we shall have a compound umbel, as in fig. 81. 



The whole taken together is called the universal umbel, while 

 those supported by the secondary axes arc partial umbels. 



7* 



