Third International Conference on Genetics, pp. 446-462 (1906)

LECTURE ON HYBRID PELARGONIUM GRANDIFLORUM NANUM

By MAX BÜRGER, of Halberstadt, Germany.

MY predilection for Pelargonium grandiflorum, generally called 'English' or 'Odier,' commenced in my childhood. At that time these plants were more favoured by the amateur than by the professional horticulturist, and were only occasionally to be found in nursery gardens. Precisely for that reason, the impression made on me—a gardener's son—was at that time so great that even now I am charmed by the vivid recollection of those sitting-room windows, which were yearly filled with a wealth of bloom by these pelargoniums.

* Herr Bürger's opinion that his pets are capable of absorbing free nitrogen from the atmosphere must be accepted with caution as at least "not proven," indeed the present state of our knowledge on the subject would seem to make it improbable. EDITOR.

The striking luxuriance of pelargoniums, even without the care of a gardener, and in small overcrowded dwellings, particularly in rural cottages in the vicinity of dung-heaps &c., can be explained by the fact that pelargoniums are to a great extent capable of absorbing large quantities of nitrogen from the atmosphere* by means of their fine, small glandular hairs. A better explanation of this lies, however, in the fact that the pelargonium, being a native of the Cape, thrives better in winter in the dry atmosphere of a room than in the humid one of a greenhouse.

As a young gardener, I found later, that is about thirty years ago, in some nursery gardens, a rich assortment of these pelargoniums. Their names showed that they were of a French and English strain.

I was greatly impressed by their splendid range of colour, but not at all by the beauty of the plants, which were mostly long and straggling, each individual branch having to be supported by a stick. After the short blooming season, it was a leafless, weak, undesirable-looking skeleton.

Twenty years ago, I greatly admired the large variety of colour, which had been derived from the original type-colour (white with pinkish-lilac pencillings), but at the same time I regretted that it had then been impossible to give to the plants a finer, more vigorous growth, and a more robust constitution. By degrees many gardeners took up the culture of pelargoniums, and many novelties were obtained in England, France, and Austria, but only a few were perceptibly better in the above respect.

Some of the best varieties were 'Mabel,' 'Mme. Thibaut,' and 'Viennese Pearl,' which soon became widely known and distributed everywhere. They were propagated in many nurseries, particularly in Vienna and Zittau, in large quantities, and in the springtime became more and more popular market plants.

The rapidly increasing popularity of these plants with the public induced most gardeners to cultivate them; but many soon gave up the cultivation again, as they required too much attention.

Now I also followed my hobby, and entirely gave myself up to the cultivation of these plants.

I had a strong determination and also a conviction that I should succeed in improving the plants and rearing one easy of culture, and at the same time a fine specimen of good marketable value. I justified myself in this hope by my former success in obtaining new strains of vegetables and annuals by hybridisation. My stock-gillyflower strains, 'Giant Excelsior' and 'Large-flowered Victoria Bouquet,' and my keeping-beans, more especially 'Bürger's Fadenlose' (Bürger's Stringless), are still in the front rank.


FIG. 129.—SEEDLING HYBRID PELARGONIUMS.

At that time I was practically the only one to occupy myself with such hybridisations, in order to procure a specific improvement, or a particular colour which was lacking in the strain, instead of leaving it to chance, as was usually done.

Through my many hybridisations, I had learnt much by careful observation, and arrived at many new and interesting facts which I hoped to turn to good account in my study of pelargoniums.

I did not conceal from myself that these experiments with pelargoniums would involve me in greater difficulties, and much greater expense and expenditure of time, than the experiments with annuals. Without either great trouble or expense, I could soon bring the annuals into bloom in the open; while to do so with pelargoniums required at least a whole year's cultivation in a frame. Therefore I entered on this task after much deliberation and careful consideration, in order not to waste too much time and money. However, it has required a far greater sacrifice than I at first anticipated.

During the first years the results were altogether insignificant, and it was only after fifteen years of the most arduous exertions' that it was possible to exhibit the first collection which showed an entirely new strain, of which the distinguishing features at once arrested the attention of the beholders.

These improvements have been retained in every way, so that my strain is now known all over the world, and wherever it is introduced all the old types are supplanted.

In spite of this I work, year in, year out, unceasingly, for the perfecting of my pelargoniums, as I have not yet entirely gained the high standard of excellence which I have set before myself to aim at, and to which new ideals may constantly be added.

I set myself the task of eliminating from these plants their worst faults:

  1. Their long straggling habit of growth.
  2. Their poor foliage.
  3. Their liability to aphis attack.

But I am still striving to fix in them further improvements, e.g. perpetual bloom during the whole summer, their utility as bedding-out plants, and tenacity of blooms.

1 perceived that my first and foremost task was to raise a compactly-growing plant, which my experience with other plants had shown was possible. Almost all plants grown from seed, sooner or later, acquire a low habit of growth; thus we have dwarf forms of almost all annuals, e.g. dwarf stocks, dwarf asters, dwarf phloxes, dwarf balsams, &c., also dwarf peas, dwarf beans, &c. And we frequently meet with these dwarf forms amongst wild plants, particularly under trees.

The dwarf forms are produced for the most part in elevated situations, but they also exist in the plains; and, as I have already said, they particularly frequently occur in the course of cultivation.

I have often pondered over the problems of these developments, and the horticultural science of that time gave no evidence whatever as to how these dwarf forms could be arrived at with certainty.

My observations indicated that the dwarf forms must have conditions of life which hindered them from arriving at a full development of their normal growth.

Therefore the problem was to manufacture such conditions! At this time there came to my assistance an old gardening experience which is expressed in the well-known proverb: "New seed, much growth; old seed, much fruit," and likewise in the world-wide remark, "This tree has flowered itself to death."

The underlying meaning of both these sayings is identical, or, at all events, both rest on the same law of Nature, which I wish to express in the following terms:

All vegetable life in the grip of death, seeks, with the last strength it has, to reproduce and disseminate itself, e.g. the tree which has flowered itself to death has, for certain, in the previous year felt the death germ, and for that reason used up all possible nourishment, in the forming of flower-buds only, which otherwise would have gone to the enlarging and strengthening, of the whole growth. We can, moreover, still further apply the above-mentioned saying, in that we may say, the younger and more vigorous a tree is, the poorer the show of blossom; the older and more miserable, the richer. Also the other proverb: "New seed, much growth; old seed, much fruit," is explained by the same fundamental principle, in that with age the seed loses, in a recognisable manner, its germinating capacity; it therefore is also an organism which is in the grip of death, and will consequently be at more pains to use up less strength towards the growth of the plant than for the speedy formation of numerous reproducing organisms.

For this reason I used in my propagating experiments only those organisms which were commencing to show signs of decay.

At the same time I also tried crossing this 'Odier-Pelargonium' with all the other species of pelargonium that I could obtain, in order—if possible—to procure an upright form instead of the old straggling bush form.

During the first years of my experiments, I had scarcely any results worth mentioning. The seedlings always became taller, some of them reached one metre in height before they bloomed, and the results of my labours had for the most part to go to the rubbish heap. My colleagues, when they visited me, laughed at my extraordinary efforts in culture; yet I did not allow myself to be discouraged, but was content with the smallest signs of improvement, in the hope that in succeeding generations better results would be visible.

Though the results of my efforts were apparently so poor, they were, nevertheless, extremely interesting, and they also kept observation and expectancy at the utmost stretch, although the sacrifices involved were most discouraging.

I have quietly continued following the prescribed method, and found even in the next generation of seeds a marked advance, which yearly became greater and more astonishing, until ultimately I arrived at the upright form and my seedlings in the autumn are more like young primulas than pelargoniums. The stem has quite disappeared, and only a full luxuriant rosette of leaves clothes the pot, in the middle of which in the spring, often as early as February, the flower-buds appear. This has become the typical form of my strain, of which the principal feature consists in the height of their growth being limited and always restricted to one central truss, which then forms side-shoots out of all the axils of the leaves, which in their turn end in trusses of blooms, so that the plant presents a compact low mass of foliage overshadowed by a splendid bouquet of bloom.

In the meanwhile the foliage has also become much more luxuriant; not only thicker, owing to its low growth, but also the individual leaves are larger, darker, more succulent, and more vigorous. I consider that for these results I am indebted to crossing with zonal pelargoniums. In this hybridisation I next proposed to import into the large-flowering varieties the fire or scarlet-red of the zonals, and also to make the leaves capable of resisting the attack of aphides.

I was not for a time successful in either of these aims, but could constantly detect more favourable indications in the foliage.

At this point I should say that the hybridisation between these two plants presented unlooked-for difficulties, which were, in fact, only overcome after I had made improvements in both, following out the theory of Herr Lindemuth, Inspector of Gardens. But even after this I was only successful in the crossing between these two plants when I used Pelargonium grandiflorum exclusively as seed-bearer (female plant). With the zonal pelargonium as seed parent unfortunately I never succeeded.

I should have expected better results if I had been able even once to make the zonal pelargonium the female plant. I explain to myself the failure of the zonal pelargonium to become the seed-bearing parent in the following way, but whether my theory is correct or not I do not know.

*In the process of translation we are afraid this sentence has become confused. The pollen-tube proceeds from and grows out of the pollen grain, so that Herr Bürger probably means that the tube proceeding from the grain of P. grandiflorum pollen may be too large to find its way through the style of the zonal. But this appears to us somewhat improbable.—EDITOR.
† ‘Perle von Halberstadt u. Fr. Engel.'

Since Pelargonium grandiflorum is larger in all parts of its blossoms than the zonal pelargonium, its pollen grains may be too large to find an entrance into the pollen-tube of the zonal pelargonium, and therefore fertilisation becomes impossible.*

It is a most disappointing thing that most crossings, and those precisely the most difficult and the ones from which the best results are to be looked for, produce infertile seedlings. It is just these that are so important in the continuation of further fertilisation, that the experiment must be repeated, with, according to circumstances, either the female or male plant, until the desired result is obtained. I have, in fact, found this to be the case in obtaining the scarlet colour as the result of hybridisation between these two parents. I had unfortunately to reject, amongst the most remarkable hybrid seedlings, those which most distinctly exhibited the zonal strain, because they were absolutely infertile, and I had to snatch at those in which I could detect the smallest zonal trace. These were always crossed again with the scarlet zonal, till finally I arrived at my originally longed-for fiery-red strain,† 'Friedrich Engel.'

Now it became easier to raise a scarlet. There followed from this 'Andenken an Wildpark,' and ultimately 'C. Holzmann.' This last shows a pure scarlet with a dark blotch, but unfortunately is completely infertile, and therefore cannot be used for further experiments in hybridisation. This is the more unfortunate since a similar pure scarlet has never, up to the present time, appeared again in my seedlings. This one always reminded me of quite an old variety—'Hofgartner Huber,' which had quite a small bloom, but of a clear scarlet colour, and was also completely infertile; in fact, the generating organs were mostly quite absent. I believe this variety was also a hybrid between Pelargonium grandiflorum and Pelargonium roseum (rosodorum).

I have come to the conclusion that one may make the following rule with regard to pelargoniums—namely, that every hybrid which has inherited an equal number of features from both parents is always infertile, and those only are fertile which incline more to one side, and that the female side.

I had much trouble in producing deep, dark blotches in the scarlet.

At first, all the fiery-red blooms were without markings—'Fireball,' 'Perle von Halberstadt,' &c. Later on I succeeded in getting a small dark marking in 'Fr. Engel,' but even this was not velvety enough. Only after I had crossed this fiery-red strain with a violet did it present larger, darker, velvety blotches. But through crossing with the violet I had spoilt my fiery-red, which had been obtained with so much trouble, as then there appeared more of a carmine colour.

I crossed and recrossed them a multitude of times before I arrived at a fiery-red with beautiful dark blotches, as in 'Andenken an Wildpark' and 'C. Holzmann.'

I am still striving to get more of the influence of the zonals into my strain, because by so doing I hope to ultimately make it free from aphides.

In my latest novelties there appears also to be more peltatum influence than formerly, and this shows its effect in a remarkable manner in the progeny.

I had not set any great store by the crossings with peltatum, because I had not found anything remarkable as the direct results therefrom. I only arrived at a violet variety, 'Grossmütterchen,' [Grandam] in which the parentage was easily detected by the form of its blooms and the scent of its foliage. However, this plant disappeared ten years ago, because I did not think it sufficiently worthy to take the place of a female plant in my hybridisations. Since that time I have never crossed with peltatum again. So much the greater, therefore, was my astonishment when a few years ago a seedling came to me which certainly owed its parentage to peltatum:

(1) By the smell of its leaves, and
(2) By the peculiar sort of hoariness of the upper parts.

This is the variety "Ballkönigin," [Belle of the Ball] one of my best, for it succeeds splendidly in window boxes, and on balconies and in sheltered positions in the open, and blooms the whole summer through.

It goes without saying that I tried to reproduce these excellent qualities in all my new varieties. I therefore owe my best results at the present time to "Bailkönigin" and to the peltatum influence, in spite of the fact that I had trusted it least of all.

Moreover, it seems to me that the blooms of these later varieties stand better—that is, they do not drop off so easily, which would certainly be a decided improvement, as then the blooms would be more valuable as cut flowers. On the other hand, the dropping-off of the petals is a promising sign because as soon as the seed-vessel has been fertilised, the blossom sheds its petals.

The artificial fertilisation of pelargoniums is in the highest degree easy and the result may be depended upon, since the pistil is so prominent that it is almost impossible for one single flower to be self-fertilised. On the other hand, for example, how difficult this is in the case of the stock-gillyflower, in which one is almost too late when one even opens the bud for the purpose.

In a reliable artificial fertilisation of a pelargonium, it is almost impossible for any foreign influence to take effect; hence the observations made in this case are of quite peculiar value.

It is of course necessary to have very exact data, from which must be constructed our fundamental rules, in order therefrom to continue constructing further and further until the ideal is attained.

To go into this with further particulars would take too long, as it involved fifteen years of work and cannot be disposed of in a few moments.

I only want to make one more observation, for which—up to the present—I have no better explanation than that even in the fertilisation of plants "inclination" also plays a part.

It is a very remarkable fact that a natural hybrid multiplies more rapidly; firstly, it is seldom quite infertile, and secondly, its descendants are nearly always constant—that is, they retain the new qualities. On the other hand, artificial hybridisation produces many infertile hybrids, of which the descendants always revert to the type. As an example of this:—The Stock which was a natural hybrid between the Dresden and summer Stock formed a white 'Excelsior' stock and remained constant; that is to say, my next year's seedlings produced only symmetrical plants with one peduncle, and none at all which reminded me of the primitive 'Dresden' form. But when I crossed this new variety with coloured 'Dresden' and 'Giant' varieties (Riesenbomben), in order to arrive at an 'Excelsior' with a variety of colours, I had in the following year scarcely one quite true-coloured plant amongst them; even the white ones had reverted. From this it took six years before I arrived at an assortment of ten constant colours.

In conclusion, I wish to say that if I have accomplished much with my pelargoniums, as appears to be the case from the numerous recognitions which I have received from people of all countries, I am still far from having attained the ideal which I have set before myself, since with each new result obtained one's aims become wider, and it would be a source of great pleasure to me to see at least some of these realised.

Above all, I should like to advance so far that pelargoniums would be raised entirely from seeds, as is the case with cinerarias and primulas. Visitors to my nurseries, where thousands of seedlings are raised annually, are always charmed with them, and believe this time to be not far off.

In a conscientious raising of seeds, my strain remains entirely constant and I obtain a great variety of the most charming colours, of which scarcely two are quite the same. It needs no gardener to say that a strain grown from seeds is much more satisfactory than one grown from cuttings, for there is much more vigorous growth in a seedling.

Finally, people will be won over to a strain from seed, because the greater the wealth of bloom and the longer the blooming season lasts, so much the less will be the formation of a growth suitable for cuttings.

Thus my aim must be to get a more plentiful production of seed which will germinate with more uniformity, as at present some germinate at the end of fourteen days and others not for six months.


Gartenflora 51: 56 (1902)

1 Scöhn Illa
2 Die Braut
3 Garteninspector Mönkemeyer
4 Gretchen
5 Frau Amalie Bluth