Inflorescence Types

This page is taken from the Northern Ontario Plant Database website.


Spike - an elongate, unbranched, indeterminate inflorescence with sessile flowers.

Spikelet - a small spike, characteristic of grasses and sedges.

Raceme - an elongate, unbranched, indeterminate inflorescence with pedicelled flowers.

Panicle - a branched raceme.

Corymb - a flat-topped raceme with elongate pedicels reaching the same level.

Compound Corymb - a branched corymb.

Umbel - a flat-topped or rounded inflorescence with the pedicels originating from a common point. Umbels can be determinate or indeterminate.

Compound Umbel - a branched umbel, with primary rays arising from a common point, and secondary umbels arising from the tip of the primary rays.

Capitulum (or head) - a dense vertically compressed inflorescence with sessile flowers on a receptacle and subtended by an involucre of phyllaries, characteristic of the Asteraceae. Heads can be determinate or indeterminate.

Thyrse - a many-flowered inflorescence with an indeterminate central axis and many opposite, lateral dichasia; a mixed inflorescence, with determinate and indeterminate shoots.


Simple Cyme or Dichasium - a determinate inflorescence with 2 dichotomous lateral branches and pedicles of equal length.

Compound Dichasium - a branched dichasium.

Compound Cyme - a determinate thyrse.

Helicoid Cyme (or bostryx) - a determinate cyme in which the branches develop only on 1 side, due to the abortion of opposing paired bud, the inflorescence thus appearing simple.

Cincinnus - a tight, modified helicoid cyme in which the pedicels are very short.

Scorpioid Cyme (or rhipidium) - a zig-zag determinate cyme with branches developing alternately on opposite sides of the rachis, due to abortion of opposing paired bud.

Banner photo of Castilleja indivisa and Lupinus ssp. taken along FM 1323 north of Johnson City, Blanco County

© Tom Lebsack 2024