Passerina (plant) large enough to cover them. This gives the plants a characteristic plaited or corded appearance. The flowers of some species are borne in terminal spikes, whereas other species bear them in a four-flowered head. Bracts, usually broader than leaves and larger than the flowers, subtend each flower. This is one helpful distinction between specimens of "Passerina" and plants in the genus "Struthiola". The calyx has four sepals, forming a flask-shaped or subcylindrical tube. At the mouth the sepals spread into lobes that are shorter than the tube. There are no petals, but the lobes of the sepals are quite colourfully
Calyx of Held a mature calyx that facilitates the consistent, rapid spread of signals in the MNTB-VCN area. A select few processes occur during early neuronal development in order to ensure proper calyx formation, specifically through the influence of Fibroblastic Growth Factor (FGF), transcription factor Math5, neural cell recognition molecule NB-2, and ephrin (Eph) proteins in cells. Math1/Math5 and FGF are two regulators essential for appropriate growth and development of the cochlear nucleus complex, which comprises both the ventral cochlear nucleus (VCN) and the dorsal cochlear nucleus (DCN). Sufficient FGF levels ensure proper morphology of the cochlear nuclei, while Math5 insures correct size