Purple hyacinth bean is often grown as a flowering plant, although most of the plant is edible. With shades of purple in the leaves, stems, flowers and showy seed pods, it is undeniably eye-catching. Purple hyacinth bean is a very vigorous grower and the vines are a popular choice for a quick cover, although they can frustrate you by refusing to flower until late in the season.The bright green, pointed leaves grow in leaflets of three leaves. The stems and undersides of the leaves are tinged purple. Flowers resemble sweet peas, without the scent. They grow in loose clusters and come in pale purple and white. They are followed by glossy purple pods that start off looking like snow peas, but eventually fill out and plump up.