The Garden: an illustrated weekly journal of gardening in all its branches 80: 583 (1916)
Experiments in raising double sweet scented Begonias
John G. White

A parent of the double sweet-scented Begonia
B. Baumanni, from the figure in the "Botanical Magazine," t. 7540. It is a native of Cochabamba in the Eastern Andes of Central Bolivia.

"A Gem in Form and Sweetness"
The first double sweet-scented Begonia

PERHAPS no flower has been improved in such a marvellous manner since its introduction into this country as the tuberous Begonia. The hybridist seems to have attained perfection, especially in the double section. Begonias now rival Roses, Camellias, Hollyhocks and Paeonies in beauty, but all have lacked that quality which enhances the value of every flower—a sweet perfume.

For the past ten years I have been endeavouring to raise double sweet-scented Begonias. I hope this account of my experiments will interest the readers of THE GARDEN, and induce some of them to take up the interesting hobby of cross-fertilisations

How can scented Begonias be raised? This problem was solved in 1891, when a sweet-scented species was discovered at Cochabamba, in the Eastern Andes of Central Bolivia. Seeds of this variety were sent to a Dr. Baumann, who forwarded them to that eminent raiser of floral novelties, M. Lemoine of Nancy. He distributed the seedlings as Begonia Baumanni. The flowers are small, ragged in appearance, pink in colour, and are borne on stiff, erect stems.

Some flowers emit their strongest perfume in the morning, and are quite scentless during the rest of the day; others breathe out their sweetness in the evening. Linnaeus called these florès tristes, or melancholy flowers, because they are generally of a dull colour. The Night-scented Stock will be readily called to remembrance as an example. Begonia Baumanni belongs to the former class. The flowers possess fragrance in a marked degree in the morning, especially in hot weather. I obtained several tubers of B. Baumanni, and when in bloom I crossed and re-crossed the flowers. The resulting seedlings displayed a variety of scents, such as cinnamon, peppermint, honey and tea rose.

In the autumn of 1906, when fertilising double Begonias, it occurred to me that it would be an interesting experiment to cross B. Baumanni with a large-flowered double. As pollen parent I chose one of the sweetest of the Baumanni seedlings. The seed parent was an extra large double of Camellia form and blush in colour. The seed ripened well and was sown the following January, the result being over a hundred seedlings, which were planted in a frame the first week in June. They all flowered in due course. Among the number were many singles and semi-doubles. There were only three really good doubles. Two of them were slightly scented; the other was a gem in size, colour, form and sweetness—in fact, the bloom was a counterpart of the seed parent, with the addition of perfume. The colour is a beautiful pale pink, with a deeper shade in the centre. The scent is difficult to define. It is somewhat like the smell of unripe Muscat Grapes when they are being thinned. The aroma, which is very pronounced in the early morning, seems to become weaker as the day grows older; but the rule is not invariable, as the relative warmth and dampness of the air affects it. The Scottish Horticultural Association recognised the value of the plant by granting it an award of merit, and at the Bath Rose Show in 1914 it created a mild sensation. The Times, in its account of the show, honoured it by devoting a paragraph to the "first double sweet-scented Begonia."

Having obtained one large sweet-scented double, I imagined it would be an easy matter to raise another, but my efforts at the second attempt ended in complete failure. On this occasion I crossed Baumanni with a specially refined Camellia double of carmine rose colour. I raised 200 seedlings from this cross. When they flowered there was not one good bloom among them, and those with scent possessed such an evil-smelling odour of carrion that I destroyed the lot. Now, here was a great mystery. The same sweet-scented pollen parent was used in each case. Two years afterwards I think I discovered the cause of the foul odour. When employing the pollen of a beautiful single, fringed, yellow Begonia for the purpose of fertilisation. I noticed the same disagreeable scent emanating from the stamens. I still have this variety, and anyone who attempts to smell the flowers turns away in disgust. The discovery of this phenomenon led me to examine the female flowers of the carmine rose double. Sure enough, the unpleasant odour was present, especially so in bright sunshine. Does all this show that the scentless Begonia was evolving scent, although not of a sweet nature? Perhaps some of the scientific readers of THE GARDEN can solve the riddle.

The third attempt was not more successful. A cross was effected between the small pink Baumanni and a large and perfectly formed Camellia double yellow. Nearly all the resulting seedlings were yellow, and there were a larger proportion of doubles among them than in any of the other crosses. One plant produced the largest leaves I have ever seen in a Begonia; the bloom was slightly scented, but of very bad form. Another scented flower was of such a drooping nature that I used it for a hanging basket; while a third, the sweetest of all, was a small, compact double, only an inch in diameter. It was a strange mixture from the same seed-pod, but herein lies the surprises of cross-breeding.

Each year afterwards I continued experimenting, but had no luck whatever except in 1913, when I discovered among the seedlings a large and beautifully modelled bloom of a blush colour, the result of a cross between Baumanni and a double white. The plant was very dwarf, and the flowers had a faint odour of a wild Rose. Crossing this with Baumanni, the following colours were obtained, all the blooms being large doubles and scented: Two blush, pure white (of bad form, but extra sweet), apricot, and rose pink, which, together with the variety raised in 1907, is the net result of ten years' work. Progress must necessarily be slow, but perhaps in the future the tuberous Begonia will gain what many new Roses lack—a sweet perfume; and has not that been aptly described as the soul of a flower?

Wynne: History of double tuberous begonias (1888)