Sea buckthorn - female

Hippophae rhamnoides. These trees are extremely hardy (zone 3), productive, and they even fix nitrogen (that is, they're self-fertilizing!). Sea buckthorn require pollination to bear fruit, and must have a male available for up to 7 female trees. Pollination is wind-based, and distance between male and female trees is critical, as planting the male too far from the females would reduce or even prevent pollination. Plant within 30 ft for best results.

Berries are bright orange when ripe (usually August-early September). These small trees / large shrubs grow to 10-12 ft in height. They're thorny, and tend to sucker, so must be planted with care - you'll probably want to be able to mow around them once or twice a year to control the suckering.
Berries have very high vitamin content (vitamins C, A, D, and E), as well as tons of essential fatty acids, Omega 3, 6, and 9. Fruit are used in baking, juicing, making smoothies, and fruit leather, as well as jams and other preserves. Leaves are used to make a herbal tea.