An extensive family, most of the species being ornamenta. plants, the taller growing sorts suitable for the borders, and those of a more dwarfish habit for the rockery. The flowers are produced in spire-like spikes, or racemes, and are generally blue; but some few species are white, and others pink.
V. Virginicum is a tall, strong-growing species, four or five feet high, with white flowers in clustered spikes; in July and August; suitable for the shrubbery.
V. Siberica has blue flowers, in spikes, in July and August; two feet high.
V. speciosa is a dwarf species, with brilliant blue flowers, in spikes; June and July.
V. azurea is two or three feet high, with fine sky-blue flowers.
V. spicata is about one foot high, with fine blue flowers.
There are as many as fifty species, all easily cultivated in almost any soil; propagated by dividing the roots.