Methods and Discoveries (1914)

Luther Burbank

*longiflorum is either a form of americanum or bulbispermum, depending on the author.

Vol. 9: The bulbous plants of the genus Crinum appear to be somewhat closely related to the Hippeastrums. There are two species known as Crinum moorei and C. longiflora [longiflorum]* that grow in Northern California, and there are numerous other species, some of which are evergreens.

A Burbank Crinum
This is a hybrid between the crinm and the amaryllis, which has developed a bulb of extraordinary size. Some specimens have bulbs larger than a man's head. The flowers are not so notable, but they have interest because of their origin

A Burbank Crinum
The crinum is an interesting member of the amaryllis family, with which Mr. Burbank has performed a very large number of interesting experiments. Unfortunately the crinums are not very hardy, else they would be much more popular in our gardens than, they are at present.

An Improved Burbank Crinum
This sturdy plant, with its beautiful lily‑like flowers, is an improved variety of crinum, developed by selective breeding. It is a flower meriting a place in any garden.

Hybrid Crinum
Mr. Burbank has hybridized the crinum with the true amaryllis, producing a plant with enormous bulbs and with pleasing, if not particularly spectacular, flowers. Unfortunately the hybrids do not bear seeds, although they blossom freely. So the experiment has not been carried beyond the first generation.

I have grown about twenty species, some of them of tropical origin. Numerous crosses were made among these species until I had a crossbred strain of Crinums of ancestry as complex as that of my Hippeastrums. The seed parent of a larger proportion of the hybrids was the species known as Crinum Americanum, but a few were grown from the seed of C. Anabilis [amabile] and C. Asiatica.

In the various crosses, the traits of the species of temperate zones appeared to be prepotent or dominant.

Interesting hybrids were produced by crossing the Crinums, not with the members of the Hippeastrum colony (this proving impossible), but with the form of true amaryllis known as Amaryllis belladonna [Brunsvigia rosea].

The hybrids thus produced were a very curious lot. They seemed undecided whether to take on the flat, strap-shaped leaves of the amaryllis or the tunicate leaves of the other parent. The compromise led to the production of a leaf with a long curious neck.

The flowers, like the plants themselves, may be described as a balanced combination of the qualities of the two parents. They are smaller than the flowers of the amaryllis, and more tubular, and in color they vary from the white of the male parent to the deepest rosy crimson, light pink being the most common color. The flowers of the amaryllis vary from rosy pink to crimson.

Although the hybrids bloom somewhat abundantly, they never produce a seed. The hybrid plants may of course be propagated indefinitely from the bulbs, constituting thus a permanent variety. But they evidence the wide gap between their parents in that they are sterile.

Vol 10:


In an earlier chapter mention was made of hybridizing experiments in which certain members of the amaryllis tribe were crossed with certain of the Crinums. It is desirable to make additional reference to some experiments in which the crinums themselves were variously developed and hybridized with rather striking results. The hybrid Crinums are a really splendid group of bulbous flowering plants in which the bulbs are in many cases of enormous size, and the leaves are broad and long, making the plants very conspicuous.

Some of the leaves, indeed, are of gigantic size, and the stalk that bears the flowers may grow to a height of from four to six feet. The flowers themselves are of variant color, from white to rosy pink, and sometimes almost purple. They are borne in profusion, and their attractiveness is often enhanced by their fragrance.

The crinums were originally residents of the tropics, being indigenous to various parts of South America, the southern United States. There are several species that are hardy in California. In some cases they will withstand freezing, so that even if the leaves are destroyed by the frost the new growth will put forth in the spring, and they will bloom as abundantly as if they had been carefully housed over winter.

Like most other bulbous plants they thrive best in sandy soil.

Some of the crinums are evergreen under ordinary temperature, others are deciduous like most of their relatives of the amaryllis tribe.

The chief objection to the crinums for house culture is the enormous size of the bulb, and the tendency to produce a superabundance of foliage out of proportion to the number of flowers; although this criticism does not apply to all of them.

Ten or twelve years ago I had probably twenty species of crinums, some of them having been brought from the tropics. My object was to combine the good qualities of the tropical and subtropical species with those of the hardy ones that had become acclimated in California. No difficulty was experienced in crossing the various species, and hybridization was carried out in the usual way, different pairs of species being mated and then the hybrid forms in subsequent seasons remated, noting of course at all stages which combinations seemed to produce the best results. Mixed hybrids were finally produced that combined the strains of many species.

The results were highly interesting.

In the course of a few years I had a strain of crossbred crinums presenting most of the desirable qualities of the different species in combination. The new plants, in spite of the strains of tropical species in their germ plasm, are very hardy, withstanding the coldest weather of this region without injury. They have very large flowers, varying in color from white, pink, and rosy crimson to purple. The petals are broad, and the flowers in a large number of cases are fragrant.

The bulbs of some of these hybrids have taken on extraordinary growth. At four years of age some of them are from six to eight inches in diameter, and twelve to eighteen inches in length, weighing probably from ten to fifteen pounds, or even more. More recently specimens have appeared of even larger dimensions. Some of these enormous bulbs seldom make offsets, others produce from one to twelve or more offsets in a season, so that they can be multiplied quite rapidly.

The seedlings from these hybrids produce plants that as a rule show a combination of two or more of the species fairly well balanced. The seed parent of the larger number of my hybrids is the Crinum Americanum, but in some cases the Crinum amabale [amabile], or the Crinum Asiaticum was the seed parent. It is observed that a certain small percentage of the hybrids show a strong propensity to run toward the seed parent of whatever species. This can generally be detected by the foliage when the plants are quite small. I have not observed that any of the hybrids depart so strongly the other way toward the tropical species (the pollen parent).

In the second and third generations the variations are better balanced through selection, and become more fixed in desired qualities than at first, when grown from seed.

On the whole, it is perhaps a little easier to get new species of crinums by crossing and selection than with most other bulbous plants, especially the lilies—although there are notable exceptions among the California lilies, some of which cross very readily.

I have sold a number of the hybrid varieties of crinum, but they have been introduced unnamed, or at least were not named by me.

The crinum seeds are very curious, in that they vary enormously in size, almost always in the same capsule. The pale-greenish bulblike seeds with irregular corrugations may vary from the size of a pea to that of an English walnut. When placed in a graded sequence they present a curious contrast. Yet the plants grown from the smallest seeds are likely to be quite as large and of the same appearance and quality as those grown from the mammoth ones. The seeds of the crinum thus furnish a unique link between seeds, buds, and bulbs, suggesting the properties of all these combined.

Another peculiarity of the seeds is that they contain so much nutriment and moisture that they may sprout and grow, making plants of considerable size, without access to any moisture except that contained within the seed itself. I have known them to sprout when laid on a shelf, or in envelopes, away from the light and entirely dry; also when sent to me by mail from Australia they sometimes started as seeds and arrived here in envelopes as small growing plants.

The crinums have been under cultivation for a long time, and interesting hybridizing experiments were made with them a century ago by the Rev. W. Herbert, Dean of Manchester, whose experiments with the gladiolus and other flowers have been elsewhere referred to. But there are many species that have not been so largely experimented with, and the opportunity to introduce new forms from the tropics, together with the striking character of the plants themselves, gives them peculiar attractiveness for the experimenter. The possibility of making still wider hybridizations, as in the case of the cross with the amaryllis, and further selections, should of course not be lost sight of.