Definition of mesarch in US English:

mesarch

adjective

  • 1Botany. Of primary xylem: developing from both the centre of the stem and the periphery, so that the oldest elements (protoxylem) are in the centre of the xylem strand, and maturation of the cells takes place both centrifugally and centripetally.

  • 2Ecology. Of a succession of plant communities: originating in a mesic or moderately moist habitat.

Origin

Late 19th century; earliest use found in Henry Garnsey (1826–1903). In sense 1 from German mesarch from meso- + -arch; compare exarch.