23.8: Inflorescence Types
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Much like leaves, flowers can be compound, becoming an inflorescence made up of many florets. And, just like leaves, inflorescences can be distinguished from individual flowers by the nodes they emerge from. A peduncle will emerge from a node in place of a branch, subtended by a leaf. A pedicel, the stem that leads to a floret, will not emerge from a node.
An important feature used in identifying angiosperms is the type of inflorescence. There are many inflorescence types, but the following are some of the most commonly encountered.
Head (also called a capitulum). Florets are clustered on an enlarged receptacle. Heads can contain one or more of the following types of florets
- Disc florets - petals are separate and all the same length; radially symmetrical
- Ray florets - petals are fused together; bilaterally symmetrical
Umbel. Pedicels converge on a single point, where they attach to the peduncle.
Spike. Florets are sessile, attached directly to a central axis
Raceme. Similar in structure to a spike, but the florets have pedicels
Panicle. A branched raceme
Use the information above to identify the inflorescence types present in your lab. In the space below, make a sketch of each inflorescence type that will help you make these determinations in the future.