Narcissus (plant) corona. Floral tubes can range from long and narrow in sections "Apodanthi" and "Jonquilla" to rudimentary ("N. cavanillesii"). Surrounding the floral tube and corona and reflexed (bent back) from the rest of the perianth are the six spreading tepals or floral leaves, in two whorls which may be distally ascending, reflexed (folded back), or lanceolate. Like many monocotyledons, the perianth is homochlamydeous, that is undifferentiated into separate calyx (sepals) and corolla (petals), but rather has six tepals. The three outer tepal segments may be considered sepals, and the three inner segments petals. The transition point between the floral tube and
Surround channels Surround channels Surround channels are audio channels in surround sound multichannel audio. They primarily serve to deliver ambience and diffuse sounds in a film or music soundtrack. Dolby Stereo (1975) was the first standard cinema sound system using a single matrixed mono rear channel (note Disney's Fantasound from the 1930s used a surround channel). Dolby Surround (1982) was the first home audio system to use a rear channel. It and its successor, Dolby Pro Logic (1987), used a single rear surround channel, but often using two speakers connected in anti-phase or a dipole radiator, as shown in the speaker configuration