Tuberous Begonia: Its History and Cultivation, pp. 64-66 (1888)
Edited by Brian Wynne
The first doubles raised were very pale and sickly in colour, generally of a washed-out pink, or dull red shade, and when a pure white, or what passed for a white at that time, was introduced, it was considered a great stride. For a long time all doubles of this colour were strongly tinted with yellow or pink, and sometimes with green; this is frequently the case even now among seedlings. They were also small and badly shaped. The introduction of Madame de Dumast and a few others gave a great lift, however, to the character of these flowers, and though none of these were really white, yet they afforded a pureness and delicacy of tint, and an elegance of form that was previously wanting, and we have now, probably more or less directly derived from these, large doubles of the purest snowy white, and of the most beautiful form. Blooms of such purity of colour and excellence of form are, however, still comparatively scarce, and first-class double whites are difficult to obtain even from the largest growers, unless ordered in good time, and price be hardly an object. For naturally, the more perfectly double a flower is, the more difficult it is to obtain pollen from it; indeed, it may be fairly stated that no pollen is produced at all by the very finest kinds. This causes the proportion of first-class seedlings to be small, and every florist knows that the more highly bred a plant is, not only is it a more difficult matter to obtain seed from it, but to raise the young plant successfully becomes a much more delicate and uncertain process.
To return a little. After a few years the deeper-coloured varieties began to assume a much greater richness and brilliancy of tint, and the lighter varieties gained a fineness and delicacy before wanting. For several years past we have noticed a decided advance in this respect, each season affording plants with blooms more and more nearly approaching true scarlet, crimson, and other shades. There are now varieties with perfectly double flowers, quite as bright and rich as the dark single kinds.
Doubles with yellow flowers have hitherto been more scarce than those of any other shade, and, in fact, until 1885 there was really no variety of this class possessing any degree of size, form or purity of colour; but during the last year or two we have seen plants and blooms far in advance of anything before produced. For a long time there was but one of this colour in commerce (W. Robinson), but this is now left quite in the shade; and doubtless having once made a start, doubles of this colour will rapidly be improved, and probably before long will attain to as great a degree of excellence as those of other hues. At the same time, these, like the single-flowered yellows, are undeniably somewhat delicate in constitution, and require skilful handling to succeed really well.