1.adjectivePertaining to plant parts that extend downward, most often applied to leaf blades that partly wrap or have wings around the stem or petiole and extend down along the stem.
2.adjectivePertaining to lamellae (the gills of a mushroom) that are broadly attached and extend down the stipe of the mushroom.
"In this group of mushrooms, the attachment of the gills to the stipe is decurrent."