2 Wild Forms and Species of Tuber-bearing- Solanums. 



in Uruguay. There is, however, reason to think that the white-flowered variety 

 was introduced into France from Uruguay by a Colonel Robido in the year 1895. 

 Many attempted pollinations were made with both varieties, but only one weak 

 seedling from each has been obtained. 



In 1901 M. Labergerie, of Verrieres, Vienne, stated that some of the tubers 

 of Solanum Commersonii (white-flowering type), which had been given him in 

 the spring of that year by Professor Heckel of Marseilles, had given rise to a new 

 variety by " sporting " or bud variation. The supposed new plant was named 

 by M. Labergerie "Solanum Commersonii 'Violet.'' (Plate 3. " Solan >u 

 Commersonii ' Violet,' " Labergerie, foliage, flowers, &c.). 



Much controversy has arisen in regard to it, since it differs entirely from Solanum 

 Commersonii in the character of its tuber, foliage, flower, and habit of growth, 

 as well as in the form and size of its pollen-grains. On account of the very close 

 resemblance in all its morphological features to the variety of the cultivated potato 

 known on the Continent as Paulsen's " Blue Giant " (Plate 4. Paulsen's " Blue 

 Giant " Potato, foliage, flowers, &c.), it has been concluded by most investigators 

 who have grown the so-called " sport " and the latter variety side by side in the 

 same soil, that a stray tuber of the " Blue Giant " must have found its way 

 accidentally into the plantations of Solanum Commersonii in M. Labergerie's 

 garden. 



(Plate 5. Solanum Commersonii, Dun., flowers, tubers, &c. Plate 6. 

 " Solanum Commersonii ' Violet,' " Labergerie, flowers, tubers, &c. Plate 7. 

 Paulsen's " Blue Giant " Potato, flowers, tubers, &c.) On reference to Plate 2 

 it will be noticed that the seed-berries are distinctly cordiform in shape, much more 

 so than is seen in any other tuber-bearing Solanum, the usual form of berry in the 

 wild species being round or slightly oval, and in almost all the cultivated potatoes 

 distinctly round. The pollen-grains shown on Plate 2 are entirely regular and 

 elliptical in form. In both these respects true Solanum Commersonii differs greatly 

 from the " sport " supposed to have been derived from it, as will be seen on reference 

 to Plate 3. 



A comparison between Plates 5 and 6 will show not only the relative form and 

 size of the tubers in Solanum Commersonii and in the presumed sport, but also 

 the fact that the tubers of the former (see Plate 5), as in the case of nearly all other 

 wild species, are borne at the extremity of long underground stolons, whereas the 

 tubers of the " sport," like all cultivated potatoes, are produced close to the base 

 of the stem. A further comparison between Plates 3 and 4 will show the complete 

 similarity which exists between the pollen-grains of the supposed sport and 

 Paulsen's " Blue Giant," and also between the seed-berries of these two. A 

 comparison of the hairs on the tips of the petals on Plates 5,6 and 7 is also suggestive. 

 It will also be seen on comparing Plates 6 and 7 that the tubers of the supposed 

 sport and Paulsen's " Blue Giant " correspond in all respects. 



Besides Solanum Maglia and Solanum Commersonii, I have had the following 

 wild species under observation and experiment at Reading : 



1. Two distinct forms of Solanum tuberosum sent me by Mr. Stuart, of the 

 Vermont Experiment Station, U.S.A. One of them, collected in Mexico, Mr. 

 Stuart considered to be a practically unaltered ancestral form of Solanum tuberosum. 



