Goniothalamus calvicarpus is a species of plant in the family Annonaceae. It is native to China, Laos and Thailand. William Grant Craib, the British botanist who first formally described the species, named it after its hairless fruit ( and in Latin).
It is a tree reaching 3âÂÂ4 meters in height. Its young branches have fine rust colored hairs, while mature branches are smooth, dark brown, with a ribbed surface and prominent lenticels. Its petioles are 5 millimeters long with a channel on their upper surface. Its moderately leathery, oblong leaves are 19âÂÂ29 by 4âÂÂ6 centimeters. The leaves have 15âÂÂ17 pairs of secondary veins emanating from the midrib. The margins of the leaves recurve. Its solitary flowers are in axillary positions on 8âÂÂ19 millimeter long pedicels. Its 3 oval sepals 11âÂÂ18.5 by 8âÂÂ15.5 millimeters and have hairs on both surfaces. Its flowers have 6 petals in two rows of 3. The outer petals are 21âÂÂ46 by 4.5âÂÂ18 millimeters with fine hairs on both surfaces. The inner petals are coherent at their base. Its flowers have 75âÂÂ120 stamen that are 2 millimeters long. Its gynoecium have 15âÂÂ35 carpels that are hairless and 1 millimeter high with stigma that are 2 millimeters long. Its seeds have slightly wrinkled surfaces.
The pollen of G. calvicarpus is shed as permanent tetrads.
It has been observed growing near streams with evergreen and deciduous trees at an elevation of 250âÂÂ1500 meters.