Bejucos u ocasionalmente arbustos. Hojas generalmente con glándulas impressed in the margin (elsewhere also glands absent or present on abaxial surface near midrib and base); estípulas interpeciolares, generalmente pequeñas, and free. Flores en pseudoracimos, éstos a menudo agrupados en panículas; cáliz con 10 glándulas (elsewhere sometimes 8); pétalos amarillos o turning orange or red with age; estambres 10, todos fértiles, the filaments in Nicaragua abaxially sparsely to moderately sericeous or pilose, las anteras más o menos similares, pilose at least at base in Nicaragua; ovario con 3 carpelos centralmente connados, todos fértiles, estilos 3, slender, el ápice dorsally rounded or truncate, con un estigma interno y ventral. Fruto partiéndose en 3 sámaras, cada sámara con las alas laterales más grandes, generalmente 4 alas discretas, el ala dorsal más pequeña, alitas intermedias o proyecciones presentes.

Género con ca 30 especies distribuidas desde México hasta Argentina; 2 especies en Nicaragua.

1. Láminas initially tomentosas en el envés, los tricomas with longest stalks 0.025—0.15 mm, the longest trabeculae 0.75—1.75 mm, straight, sinuous and tortuous, the straight usually lost first and the tortuous most abundant; flowering pedicels (above the most proximal in pseudoraceme) usually equal to longer than the peduncle, the surface totally obscured in bud by pubescence and nearly so in flower and fruit; samara nuts moderately spreading tomentose, the trichomes with longest stalks 0.025—0.05 mm, longest trabeculae 0.5—1 mm, tortuous or tortuous and sinuous ... G. mortonianum

1. Láminas initially moderately seríceas en el envés, los tricomas all sessile or with longest stalks to 0.025 (0.05) mm, the longest trabeculae 0.25—0.75 (—1.25) mm, rectos o casi así; flowering pedicels (above the most proximal in pseudoraceme) usually equal to shorter than the peduncle, the surface visible even when flowers in bud (rarely totally obscured in bud), clearly visible in flower and fruit; samara nuts moderately to sparsely appressed tomentose, the trichomes subsessile or usually sessile, longest trabeculae 0.25—0.75 mm, straight and nearly straight and/or sinuous... G. selerianum