away in the wind. A ray flower is a 3-tipped (3-lobed), strap-shaped, individual flower in the head of some members of the family Asteraceae. Sometimes a ray flower is 2-tipped (2-lobed). The corolla of the ray flower may have 2 tiny teeth opposite the 3-lobed strap, or tongue, indicating evolution by fusion from an originally 5-part corolla. Sometimes, the 3:2 arrangement is reversed, with 2 tips on the tongue, and 0 or 3 tiny teeth opposite the tongue. A ligulate flower is a 5-tipped, strap-shaped, individual flower in the heads of other members. A ligule is the strap-shaped tongue of the corolla of either a ray flower or of a ligulate flower. A disk flower (or disc flower) is a radially symmetric (i.e., with identical shaped petals arranged in circle around the center) individual flower in the head, which is ringed by ray flowers when both are present. Sometimes ray flowers may be slightly off from radial symmetry, or weakly bilaterally symmetric, as in the case of desert pincushions Chaenactis fremontii. A radiate head has disc flowers surrounded by ray flowers. A ligulate head has all ligulate flowers. When a sunflower family flower head has only disc flowers that are sterile, male, or have both male and female parts, it is a discoid head. Disciform heads have only disc flowers, but may have two kinds (male flowers and female flowers) in one head, or may have different heads of two kinds (all male, or all female). Pistillate heads have all female flowers. Staminate heads have all male flowers. Sometimes, but rarely, the head contains only a single flower, or has a single flowered pistillate (female) head, and a multi-flowered male staminate (male) head. Floral structures The distinguishing characteristic of Asteraceae is their inflorescence, a type of specialised, composite flower head or pseudanthium, technically called a calathium or capitulum, that may look superficially like a single flower. The capitulum is a contracted raceme composed of numerous individual sessile flowers, called florets, all sharing the same receptacle. A set of bracts forms an involucre surrounding the base of the capitulum. These are called "phyllaries", or "involucral bracts". They may simulate the sepals of the pseudanthium. These are mostly herbaceous but can also be brightly coloured (e.g. Helichrysum) or have a scarious (dry and membranous) texture. The phyllaries can be free or fused, and arranged in one to many rows, overlapping like the