Greek Valerian, or Jacob's ladder; a genus of the monogynia order, belonging to the pentandria class of plants. There are two species, of which the most remarkable is the coruleum, with an empalement longer than the flower. It grows naturally in some places of England; however, its beauty has obtained it a place in the gardens. There are three varieties, one with a white, another with a blue, and another with a variegated flower, also a kind with variegated leaves. They are easily propagated by seeds; but that kind with variegated leaves is preferred by parting its roots, because the plants raised from seeds would be apt to degenerate and become plain.