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.
Trailing annuals with showy flowers resembling those of Convolvulus. Corolla campanulate. Fruit 4-celled, 4-seeded. The species are all South American. Generic name from nola, a little bell, the form of the flowers.
1. N. prostrata. - A prostrate annual with somewhat fleshy oval petiolate leaves and solitary axillary flowers about an inch in diameter. Corolla violet-blue, with a yellow tube.
N. atriplicifolia, paradoxa, and lanceolata are closely allied species or perhaps varieties; the first, having white, blue, and yellow, or wholly white flowers, is the best.