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.
There is great diversity in the nature and habit, as well as in the uses of herbaceous plants. One of the principal distinctions, from a practical point of view, is the nature of the root or rootstock (or underground stem); it is fibrous, fleshy, tuberous, rhizomatous, or bulbous of some degree or modification. The only modifications generally distinguished by horticulturists are the extreme forms of the bulb, tuber and rhizome. Nearly all of the bulbous plants, whether with scaly bulbs as in the Lilies, or solid bulbs (corms) as in the Crocuses, belong to three or four of the Endogenous natural orders, such as the Liliaceae, Melanthaceae, Amaryllidea, etc. We mention this fact here more particularly because it is necessary to pursue a different method of treatment for most plants of this class.
The first group of hardy perennial herbs demanding our attention is composed of what we may term florist's flowers, or those genera and species that have varied naturally or through artificial manipulation, and whose varieties are in almost universal cultivation. It is true that many of these are inferior in point of beauty to some species of more recent cultivation in gardens. And it is highly probable that many species of which we now possess only a single variety, may in a few years be represented by as numerous and variable a progeny as some of the older inhabitants of our gardens. What has recently been effected by intercrossing different species and varieties of Clematis may serve as an illustration of what might be done in this direction. The following genera include most of those garden plants belonging to the foregoing category. Anemone,1 Ranunculus,1 Paeonia, Aquilegia, Columbine, Delphinium (Larkspur), Dianthus, Pink, Carnation, Sweet William, Viola, Hearts-ease, Violet, Althaea (Hollyhock),2 Pyrethrum, Chrysanthemum, Campanula, Primula, (Polyanthus, Primrose, Oxlip), Phlox, Pentstemon, Antirrhinum, Mimulus; and Lilium, Hyacinthus, Tulipa, Crocus, Gladiolus, Fritillaria, Narcissus and Iris - with bulbous roots. Several tender herbaceous perennials are grown for the summer decoration of the flower garden; as Dahlia, Verbena, Petunia, Calceolaria, Lobelia, Veronica1, Pelargonium, etc., for their flowers; and Coleus, Canna, Amaranthus, Mesem-bryanthemum, Perilla, Iresine, etc., for their foliage.
1 Tuberous-rooted. 2 Usually treated as biennials.