Caption:
Gentian-like penstemon, Penstemon gentianoides, slender penstemon, P. gracile, smooth penstemon, P. laevigatum, and bell-flowered penstemon, P. campanulatum. Handfinished chromolithograph by Henry Noel Humphreys after an illustration by Jane Loudon from Mrs. Jane Loudon's Ladies Flower Garden of Ornamental Perennials, William S. Orr, London, 1849.