About twenty-seven species are now known, all characterized by length not excee 4 ding 06 of an inch, flat wings, three articulations in the antennae, one or two articulations in the tarses, with digitules, but without cornicles on the abdomen.
In their early state all leaves are continuous with the stem, and it is only in their after growth that articulations are formed.
The axis of the spikelet is frequently jointed and breaks up into articulations above each flower.
In any case the position of the line of pressures is confined at the lead articulations within very narrow limits, and ambiguity as to the stresses is greatly diminished.
Articular disease occurs at the joints (articulations).