A turion (from Latin turio meaning "shoot") is a specialised overwintering bud produced by aquatic plants, especially in the genera Potamogeton, Myriophyllum, Aldrovanda and Utricularia. These plants produce turions in response to unfavourable conditions such as decreasing day-length or reducing temperature.

Turion ecology of hydrilla.
Turion formation, dormancy and germination of curly pondweed, Potamogeton crispus L
Photophysiology of turion formation and germination in Spirodela polyrhiza
Photophysiology of Turion Germination in Spirodela polyrhiza (L.) SCHLEIDEN. VII. Action of Jasmonic acid
Effects of sediment anoxia and light on turion germination and early growth of Potamogeton crispus
Abscisic‐acid‐induced turion formation in Spirodela polyrrhiza L. I. Production and development of the turion
Abscisic-acid-induced turion formation in Spirodela polyrrhiza L. II. Ultrastructure of the turion; a stereological analysis
Photophysiology of turion germination in Spirodela polyrhiza (L.) Schleiden. X. Role of nitrate in the phytochrome‐mediated response
PHOTOPHYSIOLOGY OF TURION GERMINATION IN Spirodela polyrhiza (L.) SCHLEIDEN–V. DEMONSTRATION OF A CALCIUM‐REQUIRING PHASE DURING P...
An Ecological Life-History of Spirodela Polyrhiza (Greater Duckweed) with Emphasis on the Turion Phase