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
Calyx of Held causes an action potential to be triggered on the postsynaptic side – further encouraged by low internal sodium of the principal neurons. In the mature calyx, the AMPA receptors are concentrated on the principal neuron as to localize the transmission for greater action potential probability. Also note, the NMDA-type glutamate receptors contributions decrease after the onset of hearing. The mechanism behind synaptic vesicle endocytosis changes as the calyx becomes more mature. Calmodulin and calcineurin in their active form are required for vesicle endocytosis in an immature calyx; however, in the mature calyx neither calmodulin nor calcineurin are necessary. Rather, the