Historical reference: Do not rely on this information. It is very old. About this collection
Jacob's Ladder, or Greek Valerian, Polemonium caeruleum, giving its name to the order Polemoniaoeae, is a herbaceous perennial, native to the North of England, and commonly grown in gardens, sometimes with variegated leaves. It grows about a foot high, with hardly branched stems, scattered pinnate leaves, and numerous shortly-stalked blue or white pentamerous flowers, nearly an inch across.