Wisteria

This absolutely gorgeous ornamental perennial vine is known for its incredible display of showy purple clusters of flowers. On top of the beauty of this plant, it also fixes nitrogen into the soil, helping with natural "fertilization" of the grounds around the vine.
 
While technically the flowers are edible (fresh or cooked), there are reports of people having stomach aches after ingesting them, so caution must be advised and it is recommended to do your own research before consuming them.
 
The vines can reach lengths of well over 30 metres (100'). It is suggested to grow this plant along a trellis or wall.