Sea Buckthorn (Hippophae Rhamnoides)
Can be a prickly deciduous shrub or small tree, it can sometimes be evasive and can sucker. It is noted for its plentiful edible (somewhat sour) orange berries which are very high in vitamins and antioxidants, commonly found in coastal positions but which also does very well inland, even in very cold positions.
For a good supply of berries, it needs to be in a sunny situation, with a separate male and female plant. But the sex is not distinguishable until flowering - male flowers are conical and conspicuous, female are rounder and smaller.
Its very useful in wet sites (it does not like dry soil) and can fix nitrogen in the soil so its helpful in improving poor soils.