RACEME

A 'raceme' is a type of inflorescence that is unbranched and indeterminate and bears ''pedicellate'' flowers — flowers having short floral stalks called pedicels — along the axis. In botany, ''axis'' means a shoot, in this case one bearing the flowers. In a ''raceme'', the oldest flowers are borne towards the base and new flowers are produced as the shoot grows. A plant that flowers on a showy raceme may telegraph the fact in its scientific name, e.g. ''Cimicifuga racemosa''.
A 'spike' is a type of ''raceme'' in which individual flowers are ''sessile'' (that is, lack pedicels). The term 'spikelet' can refer to a small ''spike'', although it is primarily used to refer to the ultimate flower cluster unit in the grasses (Family Poaceae), in which case the stalk supporting the cluster becomes the ''pedicel''. A spikelet comprises one or more florets enclosed by two glumes (bracts), and is not a raceme.

A 'spadix' is a form of spike in which the florets are densely crowded along the axis.