A small stalk or stem, especially the rudimentary stalk of a seed embryo
a quick caulis or stem, esp. the rudimentary stem observed in the embryo of a seed; -- otherwise known as a radicle.
In botany, some or standard stem: applied to the first stem (more often but improperly called the radicle) into the embryo, to differentiate it through the cotyledons. In addition caulicule and cauliculus.