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Growing from previously ossified parts; -- opposed to autogenous. Owen. Exogenous aneurism (Med.), an aneurism which is produced by causes acting from without, as from injury.

Pertaining to, or resembling, an order of plants like the palms, but having exogenous wood. The sago palm is an example.

The heartwood of an exogenous tree.

Arising or growing from without; exogenous.

Exogenous.

d. -- Medullary rays (Bot.), the rays of cellular tissue seen in a transverse section of exogenous wood, which pass from the pith to the bark. -- Medullary sheath (Anat.), the layer of white semifluid substance (myelin), between the primitive sheath and axis cylinder of a medullated nerve fiber.

e center of the stems of many plants and trees, especially those of the dicotyledonous or exogenous classes. It consists of cellular tissue.

The alburnum, or part of the wood on any exogenous tree next to the bark, being that portion of the tree through which the sap flows most freely; -- distinguished from Heartwood.

A genus of exogenous polypetalous plants, embracing about one hundred and eighty species. See Saxifrage.

the lines or narrow plates of cellular tissue which pass from the pith to the bark of an exogenous stem; the medullary rays. In the wood of the oak they are much larger than in that of the beech, maple, pine, cherry, etc. -- Silver grebe (Zoöl.), the red-throated diver. See Illust. under Diver. -- Silver hake (Zoöl.…

Of or pertaining to a natural order (Sterculiaceæ) of polypetalous exogenous plants, mostly tropical. The cacao (Theobroma Cacao) is the most useful plant of the order.

A genus of cycadaceous plants, having the appearance of low palms, but with exogenous wood. See Coontie, and Illust. of Strobile.