Secondary cortex formation in Osmundaria prolifera (Amansieae: Rhodomelaceae)

Summary 1. The development of the pericentral cells, lateral wings, and primary cortex is briefly described in the rhodophyceanOsmundaria prolifera Lamouroux. 2. During subsequent development of the blades, a large part of the outer margins of the lateral wings is lost, presumably by sand abrasion. 3. The loss of the lateral wings appears to stimulate the primary cortex into meristematic activity, thereby producing a secondary cortex, attaining a thickness of up to 0.5 cm. 4. Secondary cortex formation in this species produces leathery, terete stipes which may be an adaptation towards perennation.