The Europa daylily (Hemerocallis fulva) is a familiar plant throughout a large part of the United States.
Colonies of this perennial with herbaceous habit of growth form dense masses of robust, grasslike foliage with numerous scopes or flower stems that bear an abundance of large, colorful blooms.
Daily, over a period of some three weeks, in early July, groups of these plants provide islands of rich orange-red color, not only in gardens but also afield as a feature of the natural vegetation.
The Europa daylily is one of the oldest plants cultivated for its flowers.
Europa Daylily World Traveller
By means of man’s cultivation it has migrated from the spot of its origin in the Orient, along the routes of early overland trade and travel from China, through India, Western Asia, and Europe and, into and across our United States.
Thus, with Man’s aid, this plant has migrated around the earth and established itself by successful escape from cultivation as a permanent element of the native vegetation.
It is a noteworthy fact that this remarkable spread and prolific multiplication has involved only vegetative propagation based on the vigorous extension of the underground sterns or rhizomes. There is little record of plants of the Europa daylily producing seeds, except for the few that have been obtained by extensive experimental hybridization pollinations.
The many thousands and perhaps millions of so-called “plants” of the Europa daylily are merely branches of one individual. Actually, the botanical status and the genetical constitution of the entire multitudinous population of this daylily are those of the original seedling.
Clones and Ramets
The term clone has been proposed to designate such a population, and the name ramet has been applied to a member or unit plant formed by a branch, especially when it is isolated.
The proper application of these terms enables botanists, horticulturists and gardeners to understand the status of clones and to recognize their important role in horticulture.
It is a fact that most perennial plants in cultivation are clones. Often a clone is an aberrant individual, a mutation, a complex hybrid, or a polyploid, that does not breed true to type from seeds or may not be able to produce seeds.
In the trade, a clone is usually referred to as a horticultural variety, though these terms also covers subjects that breed true from seed.
The most suitable names for clones are “horticultural varietal” names, such as Irish Cobbler potato and Red Radiance rose.
The term Europa daylily was proposed to provide a name for this clone of hemerocallis that is appropriate, distinctive and exclusive.
The Europa daylily was well known in Western Europe at least four centuries ago. In 1570 it was mentioned and briefly described by Lobel in the volume “Historia” under the name Liriosphodelus phoeniceus. In 1591 there was printed the first wood cut illustration of a ramet of this clone. This does not show a capsule of the plant.
The Lemon Daylily
It may be noted that the lemon daylily (our Hemerocallis flava) was also known in western Europe at the time. Then the name hemerocallis was applied to plants of the true lilies.
The Swedish botanist Linnaeus knew only two clones of daylilies which in 1753 he first called Hemerocallis Lilio-Asphodelus var. flavus and Hemerocallis Lilio-Asphodelus var. fulva, but in 1702 he simplified these names to Hemerocallis flava and Hemerocallis fulva.
The two clones which Linnaeus knew have continued in vegetative propagation to the present time under the names he gave.
Today it is to be recognized that the Europa daylily is a clone that happens to be the historical type of the “species” that has the name Hemerocallis fulva. This species exists as a natural population of plants widely distributed in the wild in the Orient.
Several clones of this species are in cultivation in China, especially for the use of the flowers as food, and two of these (the Chengtu daylily and the Hankow daylily) were brought to the United States and distributed for garden culture.
Various other members of this species have come into culture in Europe and America. Two clones which have papa-double flowers were widely cultivated in the Orient and in Europe and America.
One botanical variety with rose-pink flowers (Hemerocallis fulva var. rosea), has been recognized and members of it were distributed from the New York Botanical Garden for propagation as horticultural clones (Rosalind daylily and Charmaine daylily) and these have been extensively used in breeding.
Triploids and Diploids
The failure of ramets of the Europa daylily to produce seeds has been observed and noted over a period of at least three and a half centuries. Studies revealed that the Europa daylily was a triploid.
The somatic or “body” cells, as distinct from sex cells, have three sets of eleven chromosomes each (11+11+11), instead of only two sets, which would make them diploid (11+11) and which are characteristic and normal for all the known species of hemerocallis.
In the formation of spores (micro-spores in anthers and macrospores in ovules) in the flowers of the Europa daylily, as is the rule in triploids, there is much abortion which greatly reduces potential fertility.
Also there is complete self-incompatibility in all intra-clonal pollinations for the pollen tubes of the few microspores that are functional. These two features of sterility are frequent in plants and especially in clones that are cultivated for flowers only, in which case fruits and seeds ire not desired or important.
The Europa daylily has, however, been a parent in recent hybridization’s which were followed by selective breeding.
Its flowers have all three of the flower pigments found in daylilies, which are plastid pigments, called carotin and xanthophyll, and the water-soluble red pigment, anthocyanin. Also there is a rather complex pattern in the distribution of the coloring.
Hybridizations of the Europa daylily with members of yellow-flowered and orange-flowered species which were followed by selective breeding, often for several generations, have resulted in extreme diversity in the relative amounts of the three pigments, in the recombinations of these, and in their distribution in patterns of coloring.
If the Europa daylily were difficult to grow or merely slow and difficult to propagate, it would probably be rather highly prized as a garden plant. Many of the hybrid clones of which it, is a parent do not have wide-spreading rhizomes and are much less liable to form large colonies or become escapes from cultivation.
The Europa daylily is an inexpensive and old-fashioned plant for a modest home garden, and it is also valuable for mass naturalistic or semi-formal plantings.
by AB Stout – FG0748