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Show 78 HYBRID VERBASOUMS. CHAP. II. mediate tint but either pure white or pure yellow flowers, gener' ally of the latter ?o l our. * My observations were made In the autumn; so that I was able to collect some half-Inatured capsules from twenty of the thirty-three intermedi~t~ plants, and likewise capsules of the pure V. lychn~t~s and thapsus growing in the san1e field. All the. latter were filled with perfect but immature seeds, w~Ilst the caps.ules of the twenty intermediate plants did not contain one single perfect seed. These. plants, consequently, were absolutely barren. From this fact,-from t_he ~ne plant which was transplanted into my garden yieldin?. when artificially fertilised with pollen from V .. zychn~t~s and thapsus some seeds, though extremely few 1n. nuinber.'from the circumstance of the two pure spec1es growing in the same field,-and froin the intern1ediate character of the sterile plants, there can be no doubt that they were hybrids. Judging from the position in which they were chiefly found, I am inclined to believe they were descended from V. thaps~ts as the seed-bearer, and V. lychnitis as the pollen-bea~·er. It is known that many species of Verbascum, when the stem is jarred or struck by a stick, cast off their flowers.t This occurs with V. thapsus, as I have repeatedly observed. The corolla first separates fron1 its attachment, and then the sepals spontaneously bond inwards so as to clasp the ovarium, pushing off the corolla by their movement, in the course of two or three minutes. Nothing of this kind takes place with young barely expanded flowers. With Verbascum lychnitis and, as I believe, V. phceniceum the corolla is not cast * 'Bastarderzeugung,' p. 307. t This was fir::;t observed by Correa de Sena: see Sir J. E. Smith's 'English Flora,' 1824, vol. i. p. 311; also 'Life of Sir J. E. Smith,' vol. ii. p. 210. I was guided to these references by the Hev. W. A. Leightcn, who ~bserved this same phenomenon w1tll V. vi1·gatum. CHAP. II. HYBRID VERBASOUMS. 79 off, however often and severely the stem may be struck. In this curious property the above-described hybrids took after V. thapsus ). for I observed, to my surprise, that when I pulled off the flower-buds round the flowers which I wished to mark with a thread, the slight jar invariably caused the corollas to fall off. These hybrids are interesting under several points of view. First, from the number found in various parts of the saine moderately-sized field. That they owed their origin to insects flying from flower to flower, whilst collecting pollen, there can be no doubt. Although insects thus rob the flowers of a most precious substance, yet they do great good; for, as I have elsewhere shown,* the seedlings of V. thapsus raised from flowers fertilised with pollen from another plant, are more vigorous than those raised fron1 self-fertilised flowers. But in this particular instance the insects did great harm, as they led to the production of utterly barren plants. Secondly, these hybrids are remarkable from differing much from one another in many of their characters; for hybrids of the first generation, if raised fr01n uncultivated plants, are generally uniform in character. That these hybrids belonged to the first generation we may safely conclude, from the absolute sterility of all those observed by me in a state of nature and of the one plant in my garden, excepting when artificially and repeatedly fertilised with pure pollen, and then the nun1ber of seeds produced was extremely small. As these hybrids varied so much, an almost perfectly graduated series of forms, connecting together the two widely distinct parent-species, could easily have been selected. This case, like that of the common oxlip, shows that botanists ought to be * ' The Effects of Cross and Self-fertilisation,' 1876, p. 89. |
