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.
Tall coarse herbs, mostly natives of North America. Leaves large, simple, scabrid. Flower-heads very large, yellow with a dark centre. The Jerusalem Artichoke (H. tuberosus) is a familiar species of this genus. The name is from sun, and avoos,) a flower.
1. H. annuus. Sunflower. - This is the most familiar of South American plants, producing, perhaps, larger flower-heads than any other species in the order. There are several varieties in cultivation, differing in stature, size, and colour of flowers; and there is a double variety with all the florets ligulate.
2. H. argyrophyllus. - This is an allied species in which the leaves are clothed with a soft silky silvery down. It grows about 6 feet high, with rather smaller flower-heads of the same colour. Some garden varieties appear to be intermediate between this and the preceding.
3. H. multiflorus (fig. 133). - Perennial, about 4 or 5 feet high, with more numerous smaller flower-heads. There is a double variety in cultivation.
4. H. orgyalis. - A perennial species as tall as the Common Sunflower, but much slenderer, and narrow-leaved. Flower-heads comparatively small and numerous, forming a large panicle.
Tithonia splendens, or Comaclinium aurantiacum, is a handsome half-hardy perennial from Mexico, growing about 5 or 6 feet high, with large 3-lobed leaves and .Zinnia-like scarlet flowers produced in Autumn. And Harpalium rigidum is another allied plant, a native of North America, and quite hardy. It rises about a yard high, and is furnished with opposite oval leaves and yellow flower-heads about half the size of the Sunflower, but much more numerous and of longer duration.
Fig. 133. Helianthus multiflorus. (1/4 nat. size.)