Rhubarb
Rhubarb is an understated perennial veg/fruit that offers such a bounty of benefits to any habitat it grows in.
It's large almost exotic leaves offer much needed shade to insects, frogs, toads and others at the height of summer. It's deep and strong tap root brings minerals and goodness from deep in the soil up to the surface. As it's leaves die back in the autumn, it enhances the upper soils, feeding worms and other soil dwelling species with a wealth of mineral rich nourishment.
Aside from its ecological benefits, it is one of the first perennials to grow like the clappers in spring. Though the leaves are not edible, the stalks offer a beautiful, tangy and juicy treat. I still remember picking fresh rhubarb from my grandparents garden and dipping it in honey as one of my fondest childhood memories.
Suggested uses:
Dip in honey and eat raw
Cook with some butter, or a little water until the rhubarb is softened, then serve with yoghurt.
Sprinkle with oats, cinnamon and syrup/honey and bake in the oven until the oats begin to brown.