Natural Science 11(69): 327-329 (Nov 1897)

VI

The Seed Production of Cut Flowers

RUD0LF BEER

IN the second number of the Botanische Zeitung for this year (Jan. 16th 1897, p. 17) Ludwig Jost brings to light a very curious fact in historical botany. He points out that at the close of 1896 H. Lindemuth has re-discovered a phenomenon, which has already twice before been described as new.

It is a well-known feature of many bulbous plants that their flowers are normally sterile, and that their reproduction takes place exclusively by the vegetative process of bulb formation. More than three hundred years ago (1577) Konrad Gesner noticed that if the flower stalks of these plants be separated from the bulb, the flowers will set their seed. This observation, however, fell into the general oblivion which overshadowed the whole of Gesner's work. In 1790—two hundred years later—Medicus re-discovered the fact, and wrote of it in his paper "Ueber Saamenansezen an abgeschnittenen Blüthenstengein einiger Zwiebeln und Knollengewächse" (Römer and Usteri's Magazin für die Botan., vol. xi., p. 6.) He was examining the tubers of Stellarioides canalicuta (?Anthericum), and in doing so cut off the inflorescence, which he stood up in a corner of the greenhouse for the gardeners to clear away. Returning to the house a few days later he saw that the flower still remained where he had left it, and that, moreover, it was still fresh and unwithered. This interested him, and he determined to see how long it would last thus "cut off from its bulb and standing in a dry position exposed to the sun heat."

*CybeRose note: Presumably the Cape Belladonna

Stellarioides had been grown and flowered in this greenhouse during the three previous years without once setting seed. "I was no little surprised, therefore," he says, "to find that in due course of time the older flowers of this inflorescence, which had been separated from its bulb, formed true seed capsules." "This really remarkable and quite unexpected result," he continues," led me at once to other experiments. For twenty years past Amarillis reginae L.* had bloomed in this greenhouse without once setting seed; as soon as the flowers drooped, it was seen that their ovaries and all they contained withered likewise." Medicus next proceeded to cut off an inflorescence, including three flowers, and to leave this standing in the greenhouse. After a time all three flowers formed seed capsules. The same phenomenon was seen in Amaryllis formosissïma.

In discussing these observations Medicus writes:—"Those plants which have the property of reproducing themselves by roots, especially marked, are most unfortunate in setting seed, although no observer can deny the presence or completeness of the sexual organs. The true cause of this seems to be that these plants expend all their energy in increasing their roots and concentrate their nutritive activities on these parts, and so leave none over to contribute to the formation of seed. Annuals, or plants with a limited existence, on the contrary, for the most part, set seed, because they have little or no power of multiplying by their roots, which decay as soon as the seed is formed, and their allotted span of two to five months passed." Referring again to the complete sterility of Amaryllis reginae, under ordinary conditions, he adds that "scarcely, however, have we separated the inflorescence from its root, and laid it aside without moisture, than it forms large seed capsules, and clearly shows us that these would always be produced if the vigorous root formation did not rob them of all nourishment."

With the exception that we now regard bulbs and tubers as stem rather than root structures, these words have a very modern ring about them, and plainly show that what we now call correlation between the different organs of a plant was already then recognised by Medi,cus. One thing is very noticeable about his writings, and that is the charm of his literary style, an item which by no means graces too many of the scientific essays and memoirs of the present day.

Medicus' paper was written in May of 1790, and in the century which has elapsed since that time both Gesner's original observation and Medicus' re-discovery have been so completely forgotten that in 1896 Lindemuth published an account of the same phenomena without any idea that it had ever been noticed before. Thus, as Jost's paper in the Bot. Zeit. points out, we have here a fact which has three times been discovered as new, after having been twice completely forgotten. H. Lindemuth (Berichte der deutsch. Bot. Gesell., pt. 7, vol. 14), after describing precisely similar facts to those which Medicus had already set down, using, however, Lachenalia luteola and Lilium candidum as his experimental objects, proceeds to recount some facts which go beyond those which his predecessors had seen. These he embodies in a second paper, contained in the same number of the Berichte. On 25th March he cut off forty inflorescences of Lachenalia luteola, and placed them in water. About three weeks later he noticed that the lower part of the stem which was under water was now curiously granulated. Here and there a granule had become larger than its neighbours, and was easily recognised as a bulbil. At first these granules are covered by the green epidermis of the flower-stalk, but as they gradually increase in size they burst through this as little white lumps. Microscopic examination shows that these bulbils are always exogenous in their origin. Inflorescences of hyacinth which were cut off close to the bulb and placed in water then had their flowers also removed, so that nothing but the peduncle remained. When examined nearly two months later, it was found that bulbils had developed close to the places where the flowers had been situated. In this case it seems that the food-stuff in the peduncle was first cut off from the bulb, and so travelled towards the flowers, but finding its passage blocked here also by the removal of the blooms, it expends itself in forming bulbils close to their remains. Finally, Lindemuth ends his paper with practical conclusions for the culture of bulbous plants drawn from these experimental data.

This brief English note has been written in order to call the attention of those into whose hands the Bot. Zeit. does not usually fall to the services which Medicus rendered to plant biology. To glance through the pages of Professor Sachs' History of Botany, the only knowledge that we can gain of this older observer is in a few, scant, depreciating references. Granted that the light of genius did not lead him into the right path in one section of botany (anatomy) we still should not allow the memory of an enthusiastic and careful observer in other departments of the same science to be altogether forgotten, or, worse still, to be alone remembered for the errors into which he fell. Most of us, even to-day, are not always in the right, and this should teach us to "render the deeds of mercy" towards the memory of others who, living at a less enlightened period, sometimes went astray with their fellows, and did not rise above their times, but who on ether occasions saw things with an "inward light" which was denied to their contemporaries. It is no doubt the extraordinary work of Professor Sachs himself and his school which has quite placed in the shadow all older writings upon plant physiology.

The basic facts were again discovered by Hamilton P. Traub.

Traub: Reversal of Growth Dominance (1935)

Separating stems from plants