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.
Annual herbs with opposite leaves and blue or white flowers. Involucre of many imbricated linear bracts. Receptacle naked. Pappus composed of several awned scales broad at the base. This genus includes a few American species, and one widely distributed throughout the tropics. Name from a, not, and old age, probably in reference to the absence of white pappus on the achenes.
1. A, Mexicanum. - This has long been a favourite bedding and border plant, on account of the profusion of its lilac-blue flowers. There is a white-flowered variety, and recently some dwarf forms have been raised, but unfortunately their beauty is of short duration.
Coelestinia ageratoides and ccerulea are closely allied garden plants in which the pappus is toothed and cup-shaped. Mikania scdndens is a tender South American twining plant with glabrous shining cordate leaves and yellowish white flowers. It is a member of a large genus, remarkable in having almost constantly four florets in each head. Nardosmia fra-grans. Winter Heliotrope, is very near our native Butterbur, Petasvtes vulgaris, but it has fragrant flowers.
Eupatorium cannabinum, Hemp Agrimony, is one of the tallest arid handsomest native plants belonging to this order. It has hairy pinnate or 3-foliolate leaves and pale purple flowers in terminal corymbs, from July to September. Two or three Mexican species of this genus have been recently introduced, and may prove valuable for bedding purposes.