mesarch

American  

[mez-ahrk, mes-, mee-zahrk, -sahrk] / ˈmɛz ɑrk, ˈmɛs-, ˈmi zɑrk, -sɑrk /

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.

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mesarch British  

/ ˈmɛsɑːk /

adjective

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

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Etymology

Origin of mesarch

First recorded in 1890–95; mes- + -arch

Example Sentences

Similarly in the sporophylls of some cycads the bundles are endarch near the base and mesarch near the distal end of the stamen or carpel.

From Project Gutenberg

The mesarch structure of the leaf-bundles is met with in a less pronounced form in the flower peduncles of some cycads.

From Project Gutenberg

This fact is of importance as showing that the type of vascular structure, which characterized the stems of many Palaeozoic genera, has not entirely disappeared from the stems of modern cycads; but the mesarch bundle is now confined to the leaves and peduncles.

From Project Gutenberg

A point of anatomical interest is the occurrence in the vascular bundles of the cotyledons, scale-leaves, and elsewhere of a few centripetally developed tracheids, which give to the xylem-strands a mesarch structure such as characterizes the foliar bundles of cycads.

From Project Gutenberg