Rose Family — Rosaceae
The rose family is cosmopolitan and includes such important food plants as apples, blackberries, raspberries, strawberries, and garden plants like hawthorns and roses. In addition to these well-known species, one member of the family occurs in arctic freshwater environments. Members of the rose family show wide variation in growth form as the group includes trees, shrubs, and herbs. Aside from ornamental roses, this large family comprises important food plants, such as apples, raspberries, strawberries, peaches, cherries, plums, and pears. More than twenty species are found in the Canadian Arctic.
General Information and Anatomy
Most plants in this family produce cup-shaped flowers with five distinct sepals and five petals. The lower parts of the petals, sepals, and the numerous stamens are attached to the rim of the "cup".
Cinquefoils, Potentilla spp., comprise the largest and most ubiquitous arctic genus in the rose family. Cinquefoils have been used in the tanning industry, and for antiseptics and astringents, because they are high in chemical compounds called tannins. Most species grow as densely tufted herbs, although one arctic species, P. fruticosa, is shrub-like. The leaves of most cinquefoils are compound and arise from the base of the plant. Most cinquefoils have yellow flowers, but P. tridentata has white flowers and those of P. palustris are purple. Shrubby cinquefoil, P. fruticosa, is easy to recognize since it is the only cinquefoil that grows as a small, woody shrub. It is covered with reddish-brown, shredding bark and its leaves are palmate. Due to its woody nature, the Inuit use this plant for fuel.
Cloudberry, Rubus chamaemorus, is highly regarded among the Inuit (who call this plant akpik) for its soft, juicy, yellow berries, which are eaten fresh, but occasionally preserved in seal oil. Male and female flowers are produced separately, and it is the female which bears fruit, although male flowers are larger and richer in nectar. Each plant bears 1–3 leathery leaves, which are 5-lobed and somewhat resemble maple leaves.
Another tasty member of this family is the arctic raspberry, Rubus acaulis, which has pink flowers and trifoliate leaves. Unlike the familiar raspberry bushes in southern Canada, the arctic raspberry lacks prickles!
The leaves of arctic cinquefoil, Potentilla hyparctica, are grouped in trios, are hairy underneath, and resemble strawberry leaves. Its flowers are pale yellow and its petals are shaped like an inverted heart. Red-stemmed cinquefoil, P. rubricaulis, has leaves which are arranged in groups of five to seven and their undersides appear shaggy because they are covered in long, soft, white hairs. In contrast, the leaves of Vahl's cinquefoil, P. vahliana, are covered in long, silky, yellow hairs.
Marsh five-finger or marsh cinquefoil, Potentilla palustris, is important in the Arctic as it provides habitat for waterfowl and insects. Like most plants in this family, marsh cinquefoil has five sepals, as well as five petals. Insects are attracted to its flowers because of their nectar; the plants utilize these visitors to transport their pollen to other flowers for cross-pollination. The stems of marsh cinquefoil are red, like its large, sectioned leaves. It blooms late in the season – mid-July to early August – and dark reddish-purple petals with large sepals characterize the striking flowers.
Seaside potentilla, also known as Pacific silverweed, is a small plant with characteristically smooth runners, which extend from the central stem. The stem itself is enclosed by leaves to form a rosette. The flowers are yellow and underlain by glossy leaves that are green on top and have grey to white undersides.
Marsh cinquefoil thrives in a variety of habitats. It is salt tolerant, so it often grows among beach grasses on the ocean shore, but it is also commonly found on the banks of streams and freshwater pools
A true halophyte (salt-loving plant), Potentilla egedii seldom grows beyond the tidal zone, and thrives in these areas because most competitors cannot tolerate the salinity. Where it does occur beyond the reach of salt spray, this plant looks very different, growing to three times its normal size!