Corymb:   A flat-topped or somewhat round-topped capitulescence in which the lower branches and peduncles are longer than the upper.  In this example, the lower branches bearing the capitula are also longer than those higher within the capitulescence, nearly reaching the top, giving a flat-topped appearance.   Branches are straight; that is, not recurved distally.

Note that not all species exhibit perfectly-formed corymbs, particularly those which bear relatively few heads.  Some are more round- or dome-topped than the example below.  Shown below:   Sericocarpus linifolius.

Corymbiform:  Having the appearance of, but not necessarily meeting the strict definition of a corymb.  (Please also refer to the extended discussion on this subject.)