SPECIES OF TUBER-BEARING SOLANUMS. 449 
other species. Seedlings, however, of the commonly cultivated potatoes 
differ very widely from each other, those raised from the seed-berry or fruit 
generally exhibiting extensive variation in foliage, colour of tuber, and in 
habit of growth. 
I find that the pollen-grains of all these wild species are of one particular 
shape, namely oval or elliptical, whereas the pollen-grains of all the cultivated 
potatoes which I have examined are very irregular in form and size, and 
possibly degenerate. This fact is clearly illustrated on Plate 49. 
One of the forms or species which has proved of great interest, and which 
on account of its remarkable exemption from disease may become of economic 
value, is Solanum etuberosum, Lindley. This name was given by Lindley in 
1834 to a tuberless Solanum, which he states was obtained from Chile some years 
previously by the Horticultural Society. He described it as exceedingly like 
the ordinary potato, Solanum tuberosum, Linn., in all its characters, except 
that it possesses thickened rhizomes devoid of definite tubers, and the calyx 
and flower-stalks are smooth instead of hairy. 
It may be remarked here that if Lindley’s plant of Solanum etuberosum 
produced no tubers, it would have been difficult to propagate it except from seed; 
and judging by the behaviour of the plants I have experimented with, it is 
not likely that Lindley’s plants reproduced themselves from seed, for two 
reasons: Ist, that seed-berries are very rarely formed, and 2nd, when formed 
the seedlings resulting therefrom differ so markedly from the parent stock. 
It may be suggested that the Solanum etuberosum when growing in the wild 
“state, the tubers, of course, not being lifted from year to year and replanted, 
might produce tubers so small as to be mistaken for “thickened rhizomes 
devoid of definite tubers,’—or that possibly the plants which Lindley 
examined may not have been fully developed, in which case the tubers would 
not yet have been formed. 
The examples of Solanum etuberosum which 1 possess came originally from 
the Botanic Gardens, Edinburgh, in March 1887, through Mr. Lindsay, aud 
again from the same stock in 1897 from Dr. Bayley Balfour. They produced 
at first small tubers about the size of walnuts, and the calyces are hispid ; in 
other respects the plants are similar to the type specimen described by Lindley. 
Solanum etuberosum has been grown continuously for more than twenty years 
in the Trial Grounds at Reading. During that time no variation has occurred 
in the characters of the foliage or flowers of the plants. The tubers have 
also retained their original form and colour with the exception of an increase 
in size. 
Up to 1906 the plants had never been seen to bear fruits, but in that year 
a single berry was found in the centre of the plantation and allowed to ripen. 
Whether this was the product of self-fertilization or the result of a cross with 
some other Solanum growing near, it is impossible to say. 
