OCR Text |
Show 76 HYBRID VERBASCUMS. CHAP. II. produced hybrid willows is equally great.* Numerous spontaneous hybrids between several species of Oistus, found near Narbonne, have been carefully described by M. Timbal-Lagrave,t and many hybrids between an Aceras and Orchis have been observed by Dr. WeddelL+ In the genus Verbascum, hybrids are supposed to have often originated§ in a state of nature; some of these undoubtedly are hybrids, and several hybrids have originated in gardens; but most of these cases require, II as Gartner remarks, verification. Hence the following case is worth recording, more especially as the two species in question, V. thapsus and lychnitis, are perfectly fertile when insects are excluded, showing that the stigma of each flower receives its own pollen. Moreover the flowers offer only pollen to insects, and have not been rendered attractive to them by secreting nectar. I transplanted a young wild plant into Iny garden for experimental purposes, and when it flowered it plainly differed from the two species just mentioned and from a third which grows in this neighbourhood. I thought that it was a strange variety of V. thaps~ts. It attained the height (by measurement) of 8 feet ! It was covered with a net, and ten flowers were fertilised with pollen from the same plant; later in the season, when uncovered, the flowers were freely visited by pollen-collecting bees; nevertheless, although 1nany capsules were produced, not one contained a sino·le seed. During the following year this same plant ~as * Max Wichura, 'Die B;tstnrdbefruchtung, &c., der Weiden' 1865. ' t '1\f em. del' A cad. des Sciences de Toulou ,' 5e serie, tom. v. p. 28. . * 'Annales des Sc. Nut.' ge serte, Bot. tom. xviii. p. 6. . § S~e, for instance, the 4 English I< lora,' by Sit· J. E. Smith, 1824, vol. i. p. 307. . II See Gatner, 'Bastardcrzeugung,' 184.9, p. 580 . CHAP. II. HYBRID VERBASGUMS. 77 left unc~ver.ed near plants of V. thapsus and lychnitis ; but again It did not produce a single seed. Four flowers, however, which were repeatedly fertilised with pollen of V. lychnitis, whilst the plant was temporarily kept under a net, produced four capsules which contained five, one, two, and two seeds ; at th~ same ti1ne three flowers were fertilised with pollen of V. thapsus, and these produced two, two, and three seeds. To show how unproductive these seven capsules were, I may state. that a fine capsule from a plant of V. thapsus, grow1ng close by contained ove 700 seeds. rrhese facts led me to search the IUOderately-sized fie]d whence n1y plant had been re1noved, and I found in it many plants of V. thaps~~s and lychnitis as well as thirty-three plants intermediate in character between these two species. These thirty-three plants differed much from one another. In the branching of the stem they. mor~ closely rese1n bled V. lychnitis than V. thapsus, but In height the latter species. In the shape of their leaves they often closely approached V. lychnitis, but some had leaves extremely woolly on the upper surface and decurrent like those of V. thapsus; yet the deO'ree of woolliness and of decurrency did not al wa ys 0 go together. . In the petals being flat and remaining open, and In the manner in which the anthers of the longer stamens were attached to the fila1nents, these plants all took more after V. lychnitis than V. thaps~~s. In the yellow colour of the corolla they all reseinbled the latter species. On the whole, these plants appeared to take rathe1~ ~ore after V. lychnitis than V. thapwus. On the supposition that they were hybrids, it is not an anomalous circumstance that they should all have produced yellow flowers ; for Gartner crossed white and yel!ow-flowered varieties of V erbascum, and the offspnng thus produced never bore flowers of an inter- |