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Asteraceae is a family of angiosperms characterized by flowers grouped into compact flower heads. The apparent single blossom of a common daisy is an inflorescence: its small constituent flowers are florets, surrounded collectively by an involucre of bracts. A ray floret has an extended strap-like part of the corolla; a disc floret has a tubular corolla. Different members of Asteraceae have different combinations of these forms.^[ref]

The calyx may form a pappus of hairs, bristles or scales, or be absent. The dry, one-seeded fruit is often called a cypsela, although some floras use achene more broadly. These connected characters explain why classifying the whole head as one large flower loses useful anatomical information.^[ref]

For a simple observation, examine a common daisy head with a hand lens. Trace an outer ray floret toward its base, then compare the small tubular disc florets in the center. The repeated floral units belong to one organized flower head; the surrounding bracts belong to the collective enclosure. Counting apparent petals around the head therefore does not count the petals of one flower.

A disc floret is a small tubular flower within a flower head of Asteraceae. Its corolla usually ends in approximately equal lobes. In a radiating daisy-like head, disc florets occupy the central region, surrounded by ray florets; other heads can contain only tubular flowers. The word disc describes the collective arrangement, not a flat disc-shaped individual flower.^[ref]

A hand-lens comparison makes the unit clear. Lift one central disc floret from a common daisy head and follow its narrow corolla down toward the ovary. Then compare an outer ray floret with its extended strap-like corolla. Both are whole flowers, even though the outer one resembles a single petal of a larger blossom.

An illustrative count of twenty central disc florets and ten peripheral ray florets describes thirty constituent flowers, not thirty petals of one flower. Whether each unit is fertile must be checked from its reproductive structures and the species, rather than inferred just from its position.

A ray floret is a flower whose corolla has a conspicuous extended, strap-like limb, typically projecting from the edge of an Asteraceae flower head. The apparent petal around a daisy-like head is therefore part of a whole floret. It is not a single petal belonging to one giant central flower. Depending on the species, ray florets may be female or sterile; their appearance alone does not establish fertility.^[ref]

Compare an intact head with a dissection: trace one outer ray to its own base, then inspect a central disc floret. The contrast is between two floral forms assembled into one inflorescence. Counting rays around the edge does not count the full complement of constituent flowers, because it misses the central units.

Shape, position and function answer different questions. A long corolla limb can contribute to the visual display of the flower head, while reproductive organs determine whether that particular floret can produce pollen or a fruit.