Journal of the Royal Horticultural Society 24: 110-111 (1900)
Notes on some experiments in hybridisation and cross-breeding

Partial Prepotency

C C Hurst

These [Paphiopedilum] hybrids, as a whole, are fairly intermediate between their two parents, yet there is in most cases a local predominance of one parent or the other in one part or another of the hybrid. This applies equally either to form or colour.

When several hybrids from the same pair of species are compared together, this variation of the parts, of “Partial Prepotency,” as I propose to call it, becomes even more apparent and more diverse. For example, in three hybrids raised from the same parents, in the first, the pollen-parent may predominate in form in a certain part; in the second, the seed-parent may prevail in that part; while in the third, that part may be fairly intermediate between both parents; while in regard to colour, these conditions may be exactly reversed. But this only includes one part of the hybrid, and the same law applies equally to every one of the parts so that when the changes are rung on twenty or more different parts by the two parents in both form and colour, we can well understand the many possibilities of variation in hybrids of the same parentage; and I venture to suggest that this law of Partial Prepotency, founded on actual facts observed in hybrids of Paphiopedilum, may perhaps throw some light oil the question of variation in offspring of the same parents. Yet, notwithstanding this variation in the parts, it is a remarkable fact that in primary hybrids the whole plant taken together is fairly intermediate between the two parents, the balance of power being well maintained in the whole.

The greatest extreme observed by me, out of many cases in Paphiopedilum, has been 58.6 per cent. of one parent, against 42.4 per cent. of the other, the great majority being approximately 50 per cent. of each parent. This hardly coincides with the popular belief that some hybrids resemble one parent, while others resemble the other; but this may be due simply to superficial observation, for where conspicuous parts lean towards one parent, the casual observer might easily be deceived, not noticing the inconspicuous parts which compensate for this by leaning towards the other parent.