Streptanthus albidus smaller and narrower, sometimes linear in shape, and toothed or smooth-edged. Flowers occur at intervals along the upper stem. Each has a spherical to urn-shaped calyx of keeled sepals about a centimeter long with curving petals emerging from the tip. The calyx of sepals may be white to purple, depending on subspecies. The fruit is a long, narrow silique which may be 12 centimeters in length. There are two subspecies, both rare. Streptanthus albidus Streptanthus albidus is a species of flowering plant in the mustard family known by the common name Metcalf Canyon jewelflower. It is endemic to California, where
Calyx of Held calcium into the mitochondria, and providing energy for glutamate synthesis. Various glial cells are also associated with the calyx of Held. Two types of glial cells surround the calyx: astrocytes and NG glial cells. The astrocytes express glutamate transporters to remove glutamate from the synapse. This is the only known mechanism for removal of glutamate from the synapse. The NG glial cells express AMPA receptors. At postnatal day two (P2), the immature calyx of Held is formed, easily distinguished by its characteristic sealed-spoon morphology. The primary synaptic contacts that form the calyx are assembled between neurons of the MNTB (medial