Uvularia - Merrybells - A woodland perennial or any shaded or semi-shaded area. Interesting rather than showy. Drooping yellow bell flowers on drooping light green leaves, make for an interesting sight. It will spread - but not quickly.
Valeriana - Valerian. Aromatic foliage on fleshy stems for this old world garden plant. The pink or white flowers are sweetly scented and last well into the summer months. many medicinal herbal qualities for the perennial herb.
Veratrum - An imposing herbaceous perennial which does well in most garden situations, but does tend to prefer a good humus rich soil. tall panicles of flower - creamy white or the purple flowered variety - V. nigrum.
Verbascum - Mullein - Often seen growing as a wild plant in some parts of the UK, there are many choice varieties with quite beautiful spikes of flowers such as Verbascum chaixii. Yellow flowers on silver foliage is the doyen, but there is a choice of many smaller growing types with pastel shades of flowers.
Verbena - If I could only have one plant in my garden, it could possibly be Verbena bonariensis - simply because I know that year after year, it will re-seed itself and sent up the erect stems of violet-maroon flowers that are so beloved by the 'useful' flying insects. Yes, it is biennial and not perennial, but as good as! There are other hardy verbenas as well. Of which, more later.
Veronia - Ironweed - herbaceous plant with upright habit of growth but also with loosely 'attached' flowers. It is reputedly a native of the USA, but can be grown well in the UK
Veronica - Speedwell - Veronicas are not Hebes, though at one time (and still) Hebes are referred to as being Veronicas. Veronicas are herbaceous perennials - generally with blue flowers - but there are white forms as well. Erect spikes of flowers over dense carpet of foliage.
Veronicastrum - Erect and with good upright stems of flower spikes - white. Good for woodland or semis shade.