Pleiochasium
The pleiochasium is a zymous inflorescence , i.e. a special case of sympodial branching : under the terminal flower (terminal flower) of the main axis, several minor axes arise at one point. These are again bounded by a terminal bloom, below which minor axes arise. These are often reduced in number to two, so that the pleiochasium changes into a dichasium . Pleiochasia are often found in the milkweed family .
A special form of the Pleiochasium is the umbel . Brockhaus' Kleines Konversations-Lexikon defined the umbel as a "[...] form of the sympodial inflorescence, in which under a terminal flower closing the main axis at the same height from the main axis flower stalks arise, which then one of the umbel [..] .] similar inflorescence. " Due to the short main axis and the unbranched, equally long secondary axes, the inflorescence looks like an umbel . But not only the minor axes bear flowers, but also the short main axis, which can be very reduced. This terminal flower is usually the first to bloom and serves as a distinguishing feature to the umbel. After the branching point, a real umbel only has secondary axes and no longer a main axis, the flowers usually bloom from the outside in.
Scheme of a pleiochasium
Pleiochasium of the midsummer milkweed
.PNG)
literature
- Wilhelm Troll: The inflorescences; First volume . Gustav Fischer Verlag, Stuttgart 1964
- Focko Weberling : morphology of the flowers and the inflorescences; Part two . Publishing house Eugen Ulmer, Stuttgart 1981