A History of Ornamental-Foliaged Pelargoniums pp. 36-40 (1869)
I have before observed that although the varieties of Variegated Zonal Pelargoniums already in the country are exceedingly numerous, yet comparatively few of them will, I suspect, be found to be eligible as bedding plants, on account of their delicacy of constitution or deficiency of vital or growing power. Perhaps the principal cause of this, in addition to the admitted debilitating influence of variegation itself, is the practice of selecting variegated varieties for the seed-bearing parent, using the green-leaved varieties only as pollen parents. Without wishing altogether to condemn this practice, I would, nevertheless, in most instances, recommend a contrary procedure, viz., to make the green-leaved variety the seed-bearing parent, and to use the pollen of the variegated sorts, my conviction being that in the vegetable, as in the animal kingdom, the male is generally the most active in stamping the leading characteristics or peculiarities of its nature upon the progeny, while the constitution of the female is generally, to some extent, inherited by the offspring.
In referring to my own experience on this subject, I find that I have raised some pretty varieties from variegated seed parents; but the most vigorous, and in all respects the best, I have raised, have been from green-leaved seed parents.
Another cause may exist, although of it I will speak with less certainty, and that is, the using indiscriminately the pollen produced by the short stamens. It will be recollected that the stamens of the Zonal Pelargonium are seven in number, five generally being long, and two always on very short filaments, or sessile. These have sometimes been considered as sterile, or imperfect; but I have proved to my own satisfaction that the pollen produced by them is at least not always sterile; and it might perhaps be used with advantage if a dwarfing influence was considered desirable; but this is never the case with regard to Variegated Pelargoniums, as there is very little danger to be apprehended from producing them of an over robust constitution, and, consequently, the pollen produced by the short stamens may safely be dispensed with altogether.
Further, with regard to the selection of parents, the experimentalist must, of course, exercise his own judgment in the matter, bearing in mind the universal law of nature, viz., that like to a certain extent produces like, and that, consequently, the seedlings will in a greater or less degree resemble each of their parents.
To illustrate this, I will suppose that a cross is effected between a scarlet-flowered and a white-flowered Zonal Pelargonium. The seedlings will be found to vary with respect to the shade or colour of their blooms, some of them bearing more resemblance to one parent than to the other; but most probably no individual amongst them will be found to produce either scarlet or white flowers, but all of them intermediate colours—that is to say, lighter shades of red—showing that the seedlings have inherited more or less from both parents.
But in the production of Variegated Pelargoniums the foliage is, of course, more a consideration than the flowers, although there is no necessity for altogether ignoring the latter, and, therefore, every means must be used to obtain the brightest and richest combinations of leaf-colouring. Now, in the golden-margined varieties, it is where the zone, or horse-shoe mark, overlays a portion of the yellow margin, that the brightest gleams of colour are brought out. In order, therefore, to encourage or promote as much as possible that their development should assume this desiderated character, it is advisable to select, as green-leaved parents, those varieties in which the zone is situated as near as it can be found to the margin of the leaves. This rule is also conducive to the production of a tolerably large disc, or centre of green; and without this latter condition no variegated variety will be of a very vigorous constitution.
With regard to the silver-margined varieties, this consideration is perhaps even more necessary to be attended to than it is with the golden-margined sorts, as their margins are more completely destitute of chlorophyll. Possibly it is from this circumstance that they are found unable to expand in proportion to the growth or expansion of the green centres—more particularly so when grown in the open air—and thus become necessarily crumpled in the centre of the leaf, which detracts greatly from their beauty. I am therefore inclined to think, in reference to this class of varieties, that if narrower margins can be secured, although it might not altogether remedy the defect, yet it might considerably ameliorate it; for, if it did not induce the leaf to present a flat smooth surface, it would most likely compel it to assume a convex form, which would be preferable to a concave or crumpled surface.
Many other experiments will doubtless suggest themselves to the mind of the cross-breeder with regard to the improving and diversifying of the flowers, as well as the foliage, habit, and constitution of these interesting plants, concerning which it is not necessary in this place to offer further suggestions.