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.
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