Glossary of plant morphology others may form a tight spiral, or whorl, around the flower stem. First, at the base, are those non-reproductive structures involved in protecting the flower when it is still a bud, the sepals, then are those parts that play a role in attracting pollinators and are typically coloured, the petals, which together with the sepals make up the perianth (perigon, perigonium). If the perianth is differentiated, the outer whorl of sepals forms the calyx, and the inner whorl of petals, the corolla. If the perianth is not differentiated into sepals and petals, they are collectively known as tepals. In some
Calyx of Held nucleus of the trapezoid body) and VCN (ventral cochlear nerve), eventually connecting with one another by projecting across the midline of the two areas. These associations begin to appear immediately after VCN neurons have been generated; one can observe the earliest formation of these contacts around embryonic day 17 (E17). These neuronal connections, which make up an important area of the cochlea, form branches with one another that terminate in the calyx of Held. Over the course of the next two to three weeks, the neuronal contacts that first formed the embryonic calyx evolve in shape and function, culminating in