This section is from the book "The Gardener V1", by William Thomson. Also available from Amazon: The New Organic Grower: A Master's Manual of Tools and Techniques for the Home and Market Gardener.
This natural order of plants comprises only a very limited number of herbaceous genera, and none of these may be considered plants of showy character ; for, unlike the majority of the shrubby species, they are more remarkable for their curious structure than for striking beauty. The most important herbaceous genus is Epimedium, for the purposes of ornamentation: in it there is a very happy union of grace in habit and foliage and beauty, as well as high interest in the flowers. Jeffersonia is perhaps the only other genus that may be admitted into collections other than botanical, and it should be in every collection of choice beautiful plants, being at once both curious and handsome. The culture of these two genera must be the same. They succeed best in sandy loam and peat of considerable depth, and all the better if moist, though perfect freedom from stagnation must be secured, and they prefer a little shade; but that is of less consequence than a properly-constituted soil. In the mixed border they form elegant objects for the front lines, and they are very fit also for rockwork, especially where the natural soil is unfit for them - that is, heavy loam or clay.
Some of the Epimediums, being evergreen, are well adapted for furnishing the margins of beds of shrubs, their dwarf elegant mode of growth bringing about a very pleasing gradation from the shrubs to the ground edge, be it grass or box and gravel. Once established in stock, and while doing well, these plants should not be disturbed by annual deep diggings and transplantings; they dislike being much moved once they are established in a place; and only when they begin to decline, or when it may be necessary to increase stock, should they be moved. Division is the best mode of increasing these, and it is best done, especially in counties north of the Tweed, in early spring, just as activity begins to show itself returning. Of other herbaceous genera of this curious and interesting order - Caulo-phyllum thalictroides, with yellow and very fugaceous flowers, from N. America, and Diphylleja cymosa, with white flowers, also N. American, and in both which the leaves are produced twin-fashion - there is little seen even in botanical gardens in this country, and they are decidedly more curious than beautiful; fit subjects for botanical collections, in fact.
They require the same conditions in culture as Jeffersonia, to which they are closely allied.