Red globular hips -
but only if both male and female plants are present.
Rosa setigera is the only rose that is cryptically dioecious - - meaning there are male-only and female-only plants that generally look alike but whose sex is determinable microscopically, by counting the number of flowers per inflorescence (male plants have more flowers, bees are attracted to its pollen) or by looking for hips (hips are found only on female plants, pollen is sterile).
More information from the Canadian Biodiversity Project at McGill University.The US Dept. of Agriculture recognizes only two varieties of the Northern American species
Rosa setigera Michaux:
Rosa setigera var. setigera, which now also includes the thornless
Rosa setigera var. serena; and
Rosa setigera var. tomentosa which apparently has downy white hairs.
Other authorities (such as the International Organization For Plant Information) recognize, in addition:
Rosa setigera f. alba, a form with a white bloom;
Rosa setigera f. inermis, a form without prickles;
Rosa setigera var. glabra; and
Rosa setigera var. pubescens.
Horticultural selections include the thornless 'Serena' and a semi-double, striped form. In 1840, a double form known as
Kentucky Multiflora was described.
The synonym Rosa rubifolia should not be confused with
Rosa rubrifolia, better known as
Rosa glauca (Erich Unmuth, Vienna Austria).
