

THE SPECIES AND VARIETIES OF IVY. 



57 



separate species. A farther and frequent consideration of the subject favours the 

 conclusion that the differences between them, both structural and morphological^ 

 are not sufficient to establish a specific distinction. Very many examples of stellate 

 hairs from the pedicels of both plants have been examined under the microscope, 

 and in not a few instances have they been found to vary in construction to such an 

 extent as virtually to destroy this character as determining a boundary line between 

 them as species. The stellate hairs of H. helix have occasionally more than eight 

 rays, and those of H. canariensis have occasionally fewer than fifteen. Veritable 

 hairs from the Irish ivy have actually been found with only eight rays, and the 

 hairs on the sharp-leaved Irish ivy (V. Hodgensii) appear to be uniformly fifteen 

 rayed, and are more decidedly scaly than those of the plant we regard as the type 

 of this section of H. hedera. The inquirer who can forget for a time this reputed 

 distinction and will observe the more obvious characters of garden ivies, and will 

 next proceed to investigate the characters of ivies in the woods, will soon be 

 shaken in any faith he may hold in the theory that the plants are specifically 

 distinct. In the woods of the Vale of Conway, and especially in Gwydir, almost every 

 form of ivy ever imagined, figured, or described (save and except the variegated 

 forms, of which there are probably none), may be found, that is to say, if we judge 

 them by the shape and size of the leaves only. Here may be seen the smallest 

 forms of helix and the longest-lobed triangular forms of helix, and a regular 

 gradation through the whole series of green-leaved varieties, the largest leaved 

 of which come so near to canariensis as to be indistinguishable from it by any 

 observer of ordinary carefulness, though one well used to ivies may be able to say 

 that they lean more to helix and are but highly -developed forms of that type. The 

 " Lucida" and " Lobata major" of the enumeration that follows may be instanced 

 as approaching nearest to canariensis of any of the permanent garden forms of 

 helix. If the distinction we may suppose established by the stellate hairs is 

 reduced to a hair's breadth, and the distinction afforded by the most typical forms 

 of each is also reduced, where the departures from types tend towards each other, 

 to a hair's breadth, what are we to say after all about the value of that distinction 

 in the determination of species ? The so-called Irish ivy is found in Portugal, 

 the Canary Islands, Madeira, and the Iberian Peninsula ; in Ireland, it is found on 

 walls near Merrion, in the district of Killarney, and on thorn trees in the western 

 part of the Phoenix Park, near Dublin. 1 The sharp-leaved variety ( V, Hodgensii) 

 was originally found in Wicklow, but has been noted as occurring on walls near 



1 "Journal of Botany," 1864, pp. 202, 381. 



