Pappus (botany) Pappus (botany) The pappus is the modified calyx, the part of an individual floret, that surrounds the base of the corolla tube in flower heads of the plant family Asteraceae. The term is sometimes used in other plant families such as Asclepiadaceae (milkweeds), whose seeds have a similar structure attached, although it is not related to the calyx of the flower. The Asteraceae pappus may be composed of bristles (sometimes feathery), awns, scales, or may be absent. In some species, the pappus is too small to see without magnification. In species such as Dandelion or "Eupatorium", feathery bristles of the
Nutation (botany) Nutation (botany) Nutation is the bending movements executed by some plant organs, such as stems, leaves, roots, etc., by which the part is inclined successively in various directions. Nutations are due to the unequal rate of growth of different sides of the organ, an inequality which, so far as is known at present (c. 1915), is dependent upon internal (unknown) causes and is not called forth by the action of external stimuli. The word is often used in a broad sense in the phrase "nutational movement", to include all the movements in plants caused by growth in contrast to "variation