Robert Elias Fries, the Swedish botanist who first formally described it, named it in honor of Adolpho Ducke who collected the specimen he examined, and its large (grandis in Latin) flowers.

Its white flowers are on 2 centimeter long, erect, hairless, warty pedicels.

Its outer petals are 3 by 2 centimeters, have silky hairs on their inner surfaces, and come to a shallow point at their tip.

The connective tissue between the lobes of anthers is overgrown to form a flat cap covered in short hairs.

Its narrow, oval ovaries are 1.5 millimeters long and covered in rust-colored hairs.