Types of Inflorescences

Inflorescence is a term to describe the arrangement of flowers, or florets, on the stem of a plant. Single inflorescences involve all the flowers on the plant gathering in a single pattern, whereas compound inflorescences involve complex patterns formed by multiple single patterns of flowers. Inflorescences are divided into two primary categories: racemose, or indefinite, and cymose, or definite.

Corymb

In corymb inflorescences, the florets are arranged along one main floral peduncle. The stems are of different lengths so that the florets all end at the same level. Corymbs are sometimes referred to as "flat-top racemes."

Umbel

The florets on umbels all arise from the same point on the peduncle. When multiple umbels gather together, it is called a compound umbel. The secondary umbels in compound umbels arise from the tip of the primary umbel.

Cyme

Cymes have one main stem that ends in a flower. In biparous cymes, two lateral stems develop just below the flower. In uniparous cymes, a single stem develops. This growth pattern repeats at each flower.

Spike

The florets on spike inflorescences are attached directly to the peduncle. Spikes have no stems or branches. Spikelets, which are small spikes, include some sedges and grasses. Spikes have both male (stamen) and female (pistils) florets. Catkins, a similar plant to spikes, differ in that they have only male or female florets. Spadix inflorescences are thick and fleshy spikes surrounded by a funnel-shaped leaf.

Raceme

In racemes, the florets are attached along a peduncle, and the stems are similar in length. Older florets occur toward the bottom of the plant, with new florets developing toward the top. A panicle is formed when several racemes gather together.

Capitulum / Head

In capitulum (head) inflorescences, the florets do not occur on stems, but instead gather on a platform-shaped peduncle. Sunflowers are an example of capitulum inflorescences.

Keywords: types of inflorescences, types of flowers, racemose, cymose

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Sandra Ketcham is a writer with more than 15 years experience writing and editing for both print and online publications. She specializes in health, travel and parenting topics, and has articles published in regional, national and international print magazines, including "The Dollar Stretcher" and "Kraze." Ketcham is currently pursuing a degree in psychology.