Capitulum

A compact flower cluster in which many small florets sit on a shared receptacle, creating an inflorescence that can resemble one flower.

Floret: A small individual flower, often one of many grouped within a larger inflorescence. Each capitulum is assembled from these small flowers.
Ray floret: A usually strap-shaped floret found around the margin of many daisy-family capitula. Ray florets form the conspicuous outer ring in many familiar capitula.
Sunflower: A tall annual plant in the daisy family, cultivated for its edible seeds and oil-rich fruits. Its large head is a familiar capitulum with central disc florets and marginal ray florets.
Raceme: An unbranched inflorescence bearing stalked flowers along an elongated axis. Unlike a capitulum, it displays separate flowers along a stem rather than across one compact receptacle.
Receptacle (botany): The expanded tip of a flower stalk that bears floral organs or, in some plants, an entire flower cluster. It provides the common surface on which the capitulum’s florets are attached.
Disc floret: A usually tubular floret found in the central region of many daisy-family capitula. Disc florets occupy the center, where they commonly produce pollen and seeds.
Dandelion: A widespread herbaceous plant whose yellow flower heads mature into spherical seed displays. Its head is a capitulum composed entirely of strap-shaped florets.
Spike (botany): An unbranched inflorescence bearing sessile flowers along an elongated axis. Its flowers attach along a central axis instead of forming a head on a broad receptacle.
Involucre: A whorl or cluster of bracts surrounding the base of an inflorescence. Its bracts commonly enclose and protect the base of a capitulum.
Centripetal development: A pattern in which structures develop progressively from the outside toward the center. Many capitula open their florets in this outward-to-inward sequence.

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