Inflorescence parts Inflorescence Types © KPU.ca/Hort

Floret

Pedicel

Ray

Bract

Peduncle

Cyme: the growing tip becomes a floret before more arise from axillary buds. May appear corymb-like. Sometimes head inflorescences are arranged in cymes. Inflorescence Types © KPU.ca/Hort

Raceme: elongated inflorescence with floret pedicels of about equal length that develop along a rachis.

Inflorescence Types © KPU.ca/Hort

Spike: inflorescence elongate and raceme-like but with very short or no pedicels. Occasionally head-like due to very short internodes, but these are not in the Asteraceae.

Inflorescence Types © KPU.ca/Hort

Verticillaster: florets occurring in false whorls at nodes on a elongate stalk usually with pedicels and leaf-like bracts. May appear head-like (due to very short internodes), or spike-like. Members of the Lamiaceae only (mint family).

Inflorescence Types © KPU.ca/Hort

Umbel: pedicels (and rays if a compound umbel) of about equal length all arising from the apex of the peduncle. A family feature of the Apiaceae but also occurs in other families.

Inflorescence Types © KPU.ca/Hort

Corymb: florets are formed on lateral stalks of different length, the longest being at the base creating a flat-topped inflorescence.

Inflorescence Types © KPU.ca/Hort

Panicle: a main axis supports several racemes so that the inflorescence appears branched. Term often applied to any highly branched, elongate, inflorescence whose flowering sequence is unclear, even if the branching is cymose (which botanically is a thyrse)

Inflorescence Types © KPU.ca/Hort

Catkin: florets unisexual, lack petals, and tightly packed together on a rachis that usually droops downward (found only in some woody dicots, e.g. willow, birch, alder, oak). Inflorescence Types © KPU.ca/Hort

Spadix: racemose inflorescence consisting of many tiny florets on an enlarged fleshy axis which is usually partially enclosed by a large bract (the spathe). In the Araceae only.

Inflorescence Types © KPU.ca/Hort

Spikelet: inflorescence consisting of an axis (rachilla), above two bracts (glumes) and one or more very small florets with perianths reduced to paired bracts (the palea and lemma). Spikelets may be arranged in spikes, racemes, or panicles. Found in grasses and sedges.

Inflorescence Types © KPU.ca/Hort

Head (Asteraceae): florets small, closely packed, lack pedicels, and arise from a flattened axis that is surrounded or subtended by bracts to appear as a large flower. Head inflorescences may be arranged in cymes, and may be small with only a few disk florets.

Inflorescence Types © KPU.ca/Hort

Head: florets small, closely packed, lack pedicels, and arise from a flattened axis that is surrounded or subtended by bracts to appear as a large flower. Asteraceae.

Inflorescence Types © KPU.ca/Hort

Heads

can be

very

small!

Cyathium: consists of a simple female floret (one pistil) in the center surrounded by many simple male florets (one stamen each) on bracts. Found only in the Euphorbiaceae. FYI Inflorescence Types © KPU.ca/Hort

Practice identifying inflorescence unknowns

Inflorescence Types © KPU.ca/Hort

Use the

Key to the Basic Inflorescence Types

in your lab manual or lecture handouts

to identify the following unknowns.

Unknown #1

Inflorescence Types © KPU.ca/Hort

Unknown #2

Inflorescence Types © KPU.ca/Hort

Unknown #3

Inflorescence Types © KPU.ca/Hort

Unknown #4

Inflorescence Types © KPU.ca/Hort

Unknown #5

Inflorescence Types © KPU.ca/Hort

Unknown #6

Inflorescence Types © KPU.ca/Hort

Unknown #7

Inflorescence Types © KPU.ca/Hort

Unknown #8

Inflorescence Types © KPU.ca/Hort

Unknown #9

Inflorescence Types © KPU.ca/Hort

Unknown #10

Inflorescence Types © KPU.ca/Hort

Unknown #11

Inflorescence Types © KPU.ca/Hort

Answer Key

Inflorescence Types © KPU.ca/Hort

1) Catkin

2) Verticillaster

3) Head

4) Corymb

5) Raceme

6) Panicle

7) Spikelet (arranged in a panicle)

8) Cyme

9) Spadix

10) Spike

11) Umbel

Use the KPU Plant Database to search for more inflorescence type examples: Morphological Search, click Expand > Inflorescence Type