Plant reproductive morphology is asexual, producing only spores. Similarly, flowers produced by the sporophyte may be described as "unisexual" or "bisexual", meaning that they give rise to either one sex of gametophyte or both sexes of gametophyte. The flower is the characteristic structure concerned with sexual reproduction in flowering plants (angiosperms). Flowers vary enormously in their construction (morphology). A "complete" flower, like that of "Ranunculus glaberrimus" shown in the figure, has a calyx of outer sepals and a corolla of inner petals. The sepals and petals together form the perianth. Next inwards there are numerous stamens, which produce pollen grains, each containing a
Calyx of Held high frequency sound localization. This synapse has been described as the largest in the brain. The related endbulb of Held is also a large axon terminal smaller synapse (15-30 µm in diameter) found in other auditory brainstem structures, namely the cochlear nucleus. As with the calyces, these synapses promote fast, efficient information transfer. The calyx of Held holds vesicles containing glutamate on the presynaptic terminal, the vesicles are released upon stimulation (originating in the auditory system). The glutamate then binds to two known glutamate receptors, AMPA- and NMDA receptors. Commonly used in research due to its large size, the calyx