Cladium

When well preserved the polypary often shows graceful curvature of the stipe, and the cladium is the exact counterpart of the termination of the stipe, the curvature being equal in amount, but opposite in direction.

Source: wiktionary

Of the eighteen thecæ of the proximal type thirteen are usually developed before the cladium is given off. The proximal end is straight and never enrolled, though from the frequency with which specimens are broken about midway between the sicula and the cladium, it is possible that the whole did not lie exactly in one and the same plane.

Source: wiktionary

Several stages in the development of a cladium, showing the secondary nema as the leading rod of the cladial stipe (based on Bulman 1970a, Fig. 65).

Source: wiktionary