Sunday, May 31, 2015

Prickly Rose - Rosa acicularis - Rosier aciculaire

Though most people see roses all the time, the roses that you do see will tend to be one of the wide array of species and varieties that have been bred as ornamental flowers.

These are a bit different. Rosa acicularis (prickly rose, prickly wild rose, arctic rose) is a holarctically (arctic regions around the globe) distributed species [1] that hasn't been particularly altered or bred by humans.

Rosa acicularis
One of the most immediately striking differences between this species and most commercial roses is of course the number of petals. This species, like most Rosaceae (rose family), has five petals. A number of ornamental roses have been developed (from this species and others), and one of the methods of increasing the ornamental appeal of roses (and a number of other ornamentals including peonies) involves causing a transformation of the stamens into petal-like structures or into petals [2]. In a very general sense, an ornamental flower in one of these lines with many petals is more likely to be one which has been bred or selected to replace stamens with petals.

In a North American context, this plant's range is fairly broad but mostly northern. US range map here, Canadian range map here. Although it is often abundant where it actually does occur, it is actually an endangered species in Illinois, Iowa, Massachusetts, New Hampshire, and Vermont [3]. It is listed as secure in most of its Canadian range, except in Nunavut where it is sensitive and New Brunswick where it may be at risk [4]. With that in mind, please treat the species with reasonable care if you encounter it in those places where it has legal status, and with the regular respect that is due any undisturbed population elsewhere.

Solitary bee (I believe this is Hoplitis fulgida) collecting pollen from Rosa acicularis
This species reproduces vegetatively through its roots, and sexually through the production of seeds [5]. Seed production is reasonably abundant [5,6], but germination conditions have to be suitable (especially with respect to temperature) for the seeds to actually sprout [5]. R. acicularis blooms much less frequently when it grows in the forest understory (in shady areas) than in forest edge areas [5].

R. acicularis is a source of food for a number of species including the snowshoe hare, grouse, some rodents, and deer [5]. It is also a shelter plant for many birds and small mammals [5].

If you encounter this species, one of the first things you will notice if you get close is the wonderful smell. This smell is advertising to pollinators; the plant is announcing that there is nectar available, and in this case, unlike Cypripedium acaule, the advertising is accurate. R. acicularis produces plenty of nectar, which attracts bees and other pollinators [5,7]. I observed several pollinators on R. acicularis, notably those pictured in this post.

Unidentified Syrphid (bee imitator) fly on R. acicularis
Many parts of this plant are edible; the hips (bulbous fruit) are of course the most popular, primarily for use in teas, jams, or jellies because of their high vitamin A and C content. The fresh shoots and petals are also used for teas.

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