Rachis
The rachis is the main axis of the
inflorescence, or
spike, of
wheat and other
cereals, to which the spikelets are attached. It is also the part of the petiole that the pinnae are attached to in
ferns, or the main stem of a compound
leaf.
Spikelets are small inflorescences bearing one or more florets, or small
flowers, along with a set of miniature bractlike leaves. When the
fruits of the wild-type wheat are fully ripened, a series of layers forms that divides the rachis into dispersal units consisting of a single spikelet attached to a short segment of the rachis.
Encyclopedia
- Rachis is also the alternate spelling of Ratchis, king of the Lombards, 744-749.
The
rachis is the main axis of the
inflorescence, or
spike, of
wheat and other
cereals, to which the spikelets are attached. It is also the part of the petiole that the pinnae are attached to in
ferns, or the main stem of a compound
leaf.
Spikelets are small inflorescences bearing one or more florets, or small
flowers, along with a set of miniature bractlike leaves. When the
fruits of the wild-type wheat are fully ripened, a series of layers forms that divides the rachis into dispersal units consisting of a single spikelet attached to a short segment of the rachis. A ripe head of wheat is thus easily shattered into dispersal units when touched or blown by the
wind. This is referred to by
archaeologists as a "brittle rachis".
In
animal anatomy, rachis is the series of articulated
vertebrae, which encase the
spinal cord and forms the supporting axis of the body; the spine. This is also called vertebral column. In bird feathers, rachis refers to the central shaft.