An inflorescence is a shoot system that bears flowers, the individual reproductive shoots. As a unit, the inflorescence varies in morphology between species, genera, and families. Inflorescences are classified based on a conventional descriptive system utilized by taxonomists.

      Simple inflorescences consist of lateral and apical floral meristems that terminate with a solitary flower. Types of simple inflorescences include racemes, spikes, spadices, umbels, capitulums and corymbs.

      Complex inflorescence floral meristems produce multiple flowers. They can be further classified as monopodial (formation of offshoots from the main axis) or sympodial (formation of an apparent main axis from successive secondary axes). Monopodial complex inflorescences include double racemes, double umbels, and panicles. Sympodial complex inflorescences include open and closed thyrses, and cymoids.

      While such classifications are useful for general taxonomic descriptions, they have shortcomings when it comes to determining the underlying morphological and developmental relationships between inflorescence types. In an attempt to overcome some of these shortcomings, Professor Wilhelm Troll of West Germany, carried out a massive detailed survey of inflorescence morphology in flowering plants. The result of this program has been to establish a new analytical approach to the study of the inflorescence and the basis for its diversity of form.

      Troll's two major classification include monotelic, or closed inflorescence, in which the axis terminates in a flower, and polytelic, or open inflorescence, where the apical meristem aborts without the formation of a terminal flower.

      Troll has also organized the inflorescence in relation to total plant morphology. The base of the shoot is termed the innovative zone where axillary shoots grow out and replicate the vegetative growth. Just above the innovative zone is the zone of inhibition where axillary buds are inhibited and do not grow out to form an extended part of the branching system. The zone of enrichment is the region of the shoot where axillary shoots form flowering branches that replicate the morphology of the main branch. Troll termed inflorescence lateral branches that essentially repeat the morphology of the main branch paracladia. If an inflorescence is complex and forms orders of paracladia, their order is indicated by notation (Pc, Pc', Pc'', Pc''', etc.). The main axis florescence makes up the final zone of Troll's scheme of zonation. Troll's scheme provides an alternative means of studying inflorescence that does not delimit the inflorescence from the remainder of the plant's structure.

Troll's Scheme of Nomenclature

	Basic Organization of Inflorescences in Relation to Total Plant Morphology
	Monotelic Inflorescence
	Polytelic Inflorescence