mesarch

adjective

1. Botany. (of a primary xylem or root) developing from both the periphery and the center; having the older cells surrounded by the younger cells.
2. Ecology. (of a sere) originating in a mesic habitat.

adjective

1. botany (of a xylem strand) having the first-formed xylem surrounded by that formed later, as in fern stemsCompare exarch 2, endarch