decurrent

Decurrent is a descriptive term used in biology to describe a structure that continues downward along an adjacent structure rather than ending at its point of origin. The word comes from the Latin decurrere, meaning to run down.

In botany, decurrent describes leaf bases that extend downward along the stem beyond the point where the blade attaches. This can create a winged or sheath-like appearance around the stem. Decurrent leaf bases are found in a variety of plant groups, including many grasses and certain herbaceous species, and can be an identifying feature in plant descriptions.

In mycology, decurrent describes the attachment of mushroom gills. When the gills extend downward along the stalk, rather than ending at the cap margin or being free from the stem, they are said to be decurrent. This characteristic helps distinguish between different groups of gilled fungi and is used in field identification alongside other features such as cap shape, color, and spore print.

Overall, decurrent conveys a downward extension or running down along an adjacent structure, and its exact meaning is context dependent, applied to leaves in plants and lamellae in mushrooms.