Luther Burbank: His Methods and Discoveries (1914) v. 10

The Tigridia and Some Interesting Hybrids
Luther Burbank

New Charms In Far Away Flowers

About a quarter of a century ago I commenced cultivating and crossing all the Tigridias, or Tiger Flowers that were then offered by any seedsman or nurseryman anywhere in the world.

I also secured all the species of the allied genus Ferraria that I could obtain and cultivated them for the purpose of hybridizing them with the tiger flowers. The Tigridias are natives of subtropical and tropical America, ranging from Mexico to Peru and Chile. The Ferrarias are from the Cape of Good Hope, and are represented by a number of species.

Both tribes belong to the Iris family, and the two forms are so closely related that by some botanists they are regarded as properly falling within the same genus.

My own experiments, which show the ready hybridization of the various Tigridias and Ferrarias, suggest that they are closely related. Yet the fact that they are indigenous to different continents shows that they have been separated for a very long period of time, although doubtless of common ancestry.

The students of geological botany tell us that there must have been a great mass of land in the southern hemisphere at one time on which races of plants developed that subsequently were isolated on the land masses that are now known respectively as South America, Africa, Australasia, and New Zealand. At that remote period the Tigridias and Ferrarias were doubtless of one stock, and the fact that their descendants of today retain such elements of affinity as to puzzle the botanists and to serve well the purposes of the hybridizer gives another illustration of the wonderful pertinacity with which the characteristics of a plant are sometimes transmitted through almost numberless generations without radical transformation.

It is little wonder that the earlier biologists, before the coming of Darwin, when confronted with such observed cases of affinity between races that must have been separated for countless thousands of years, were strong in their faith in the fixity of species.

Yet the facts of variation, even within a few generations, are too obvious to escape attention.

And the compromise had been found, as everyone knows nowadays, in a recognition of the fact that time is long, and the further fact that natural selection may be instrumental in maintaining the fixity of a race, provided the environing conditions are unchanged, just as it may be instrumental in somewhat rapidly changing the form of a race when the environing conditions have altered.

Hybridizing the Tiger Flowers

From the outset I found that the various tiger flowers throve in my gardens, particularly in the sandy land at Sebastopol and in sandy beds especially prepared for them at Santa Rosa.

As I have already said, I began at once crossing and hybridizing the various species and varieties, and of course carried out selection among the seedlings and made new crossings, according to my usual custom. The type species with which the experiments began was the Tigridia pavonia, of which there are numerous varieties. Another form known as the Conchiflor or Shell flower was utilized, and subsequently the T. buccifera, a form more recently introduced from Mexico.

An especial effort was made to introduce also into the combination the strains of a plant of yet another genus, the Herbertia platensis. This is a tall-growing plant bearing close resemblance to the Tigridias, and by some botanists classified with them. It has pale blue flowers marked with yellow, and the specimens are of a somewhat different structure from those of the Tigridia, though the bulb and general growth of the plant are similar.

I particularly desired to introduce strains of the Herbertia platensis, because this is a very strong-growing plant, and its vigor and health would be of great service in giving hardiness which is the one thing the Tigridias more especially lack.

In particular, the bulbs of the tiger plant are difficult to keep over winter, and especially subject to decay from exposure to air and to the attacks of aphids when stored.

But much to my disappointment I was never able to effect hybridization between any of the Tigridias, either pure bred or hybrid, and the Herbertia. The experiment was made over and over, and in every case it was without result.

Meantime, however, there was no difficulty whatever in hybridizing the ordinary cultivated strains of Tiger Flowers among themselves and with some of their South African relatives. And the results of such hybridizings were manifest almost from the outset.

One of the most striking modifications shown by the hybrid Tigridias was the development of varieties having striped flowers. It might very well be expected that a "tiger flower" would be striped. But in point of fact the native Tigridias are spotted and never striped. They might with much greater propriety have been named after the leopard or panther, or better yet, considering their origin, after the South American jaguar. But the botanist who originally named them seemingly had rather vague notions as to the markings of the coat of the tiger, or else considered it sufficient that the flower itself wears a yellow mantle with dark markings.

In any event, there is something about the aspect of the flower that makes the name "tiger flower" seem not inappropriate.

And the propriety of the name becomes quite beyond challenge when my new hybrid varieties are under observation. For these are striped in a way that is very striking. Quite aside from its suggestions as to one feline or another, however, the new hybrids are flowers of great beauty and interest and differ conspicuously from any of the parental forms.

Not only are the markings thus conspicuously altered, but the flower itself is greatly increased in size. The tendency to freedom of bloom is accentuated. Moreover the hybrid plants have gained greatly in vigor of growth, in hardiness, and in resistance to disease.

The colors of the new flowers are conspicuously brightened. The striping is usually crimson on white, crimson on yellow, or yellow on crimson. In addition to presenting these stripes, which are unlike any markings of the native Tigridias, the hybrid flowers generally retain the dotting at the center that characterizes the tribe in its original form. But these dottings are greatly increased in size. In some instances, on the other hand, the dottings are partially or entirely eliminated.

The original types of these very striking new forms of Tiger Flower were readily fixed so that they breed absolutely true from seed.

It was possible, however, to increase the size of the flower by selection, and this increase in size was a permanent acquisition; also to add brilliance with new combinations of colors.

and of course the hybrid plants thus perfected exceed greatly the size of any plants that could have been developed by mere selection without crossing.

Utility as Well as Beauty

The new tiger plants, although lacking something of hardiness, were greatly improved in this regard over their ancestors.

Most of the old tigridias, as I have said, are quite subject to insects and disease. The hybrid forms are much more resistant. There is also a greater power on the part of the new plants to stand sunshine. The old tigridias sometimes withered under the influence of the sun. This might not at first thought be expected of a tropical plant, but it should be recalled that the growth of vegetation in tropical regions is so luxuriant that low-growing plants of this order are not usually subject to the direct rays of the sun throughout the day.

It goes without saying that the bulbs of the new tiger plants were improved in proportion to the stalks and flowers. The bulbs of the tiger plant are elongated and tunicated, and multiply by division somewhat after the manner of the hyacinths, tulips, and the allied races in general.

The bulbs of the new hybrid tigridias were doubled in bulk, and in come cases quadrupled, as contrasted with the parent forms. Like the somewhat similar bulbs of the gladiolus, they may best be kept in the ground over winter here in California, instead of being taken up and stored as is necessary in colder climates.

The development of the bulbs of the tigridias has not been at all a matter of accident. At all stages of the experiment in hybridizing and selection, I have paid the most careful attention to the condition of the bulbs, selecting always those that were largest, firmest and soundest. And the reason for this was not merely that such bulbs usually produce the best flowers, but also that it is worth while to improve the size and quality of the bulbs quite on their own account.

The particular reason for this is that the bulbs of the Tiger Plant are edible. When cooked like potatoes, or made into a stew, they constitute a really delicious vegetable.

To my taste the bulb of the tiger plant is at least the equal of any vegetable under cultivation. It is also highly nutritious. I am not sure that it has an equal among the vegetables of our gardens in its combination of nutritiousness and appetizing flavor.

These very qualities lead to its destruction by all kinds of animal and insect life, like the Lilium Brownii, which has no bitter principle, containing sweet and nutritious matter, and which also is attacked and appropriated by insects and other creatures.

As yet the tigridia is too tender to gain a place in the vegetable garden on a footing with the potato and allied bearers of bulbs and tubers. But when through further breeding experiments, it has been rendered more amenable to general cultivation, its bulb being at the same time still further increased in size, the tiger plant may come to be valued for its edible bulb quite as highly as for its beautiful and spectacular flower.