This section is from the book "Handbook Of Hardy Trees, Shrubs, And Herbaceous Plants", by W. Botting Hemsley. Also available from Amazon: Handbook of hardy trees, shrubs, and herbaceous plants.
Dwarf branching glandular pubescent annuals with simple petiolate leaves and large campanulate racemose flowers. Calyx deeply 5-partite. Corolla tubular - campanulate, inflated at the base. Stamens exceeding the corolla; filaments with an appendage at the base. Capsule many-seeded. Named in honour of Francis Whitla, a patron of botany.