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
; andRosa 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
; andRosa setigera var. pubescens
Horticultural selections include the thornless 'Serena' and a semi-double, striped form. In 1840, a double form known as Kentucky Multiflora
The synonym Rosa rubifolia should not be confused with Rosa rubrifolia,
better known as Rosa glauca
(Erich Unmuth, Vienna Austria).