Toadstools, mushrooms, fungi, edible and poisonous; one thousand American fungi / How to select and cook the edible; how to distinguish and avoid the poisonous, with full botanic descriptions. Toadstool poisons and their treatment, instructions to students, recipes for cooking, etc., etc.

by Charles McIlvaine; Robert K. Macadam

Orange-Yellow (aurantio-flavus), a color intermediate between orange and yellow.

Orbic´ular (orbicularis, < orbiculus, a little disk), having the form of an orb; having the shape of a flat body nearly circular in outline.

Order, the most important unit of classification above the genus.

Organ´ic, pertaining to either living or dead animal or vegetable organism.

Os´mose (osmosis, thrust, push, impel), the impulse or tendency of fluids to pass through membranes and mix or become diffused through each other.

Osmo´sis (Gr—impulsion, pushing), the diffusion of fluids through membranes; see [osmose].

Osmot´ic, of or pertaining to or characterized by osmose.

Os´tiole, Osti´olum (ostiolum, a little door), mouth of the perithecium; orifice through which the spores are discharged.

O´vate (ovatus, egg-shaped), egg-shaped; having a figure the shape of a longitudinal section of an egg.

O´void (ovum, egg, + Gr—form), egg-shaped; used to describe solids.