Named for Charles Amson, an 18th century American physician.
Perennial herbs or subshrubs, evergreen; latex white. Stems herbaceous to woody, without spines, stoloniferous. Leaves alternate, stalked; blade well developed, colleters absent at base. Inflorescence terminal, cymose. Flowers scentless, stalked. Corolla salver-shaped; tube cylindrical; lobes convolute in bud, overlapping to the left. Corolline corona absent. Stamens enclosed, attached near top of tube, not sticking to style head. Disk absent. Fruit of 2 dehiscent membranous follicles; seeds numerous, cylindrical, not winged, without hair tufts.
One species is cultivated.
Cuttings, seeds or division of clumps.
Stoloniferous perennial herb with alternate leaves and blue flowers.
About 19 species from Japan and North America.
Source: (2002). Apocynaceae. In: . Horticultural Flora of South-eastern Australia. Volume 4. Flowering plants. Dicotyledons. Part 3. The identification of garden and cultivated plants. University of New South Wales Press.