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.

© Tom Lebsack 2024

Banner photo: Ten Mile Range and Rhodiola integrifolia (King’s Crown) in Summit County