NOTES ON SOME WILD FORMS AND SPECIES 



OF 



TUBER-BEARING SOLANUMS. 



By ARTHUR W. SUTTON, F.L.S., V.M.H. 



IN 1883, Mr. J. G. Baker, F.R.S., F.L.S., at the suggestion of the late Lord Cath- 

 cart, made a study of the various species of tuber-bearing Solanums, the results 

 of which were embodied in a paper presented to the Society on January 17th, 1884.* 



Lord Cathcart was interested chiefly in the discovery of some wild species of 

 tuber-bearing Solanum which could be utilised for crossing with the commonly 

 cultivated potato, in the hope of obtaining new forms capable of resisting the 

 attacks of potato-disease fungus, Phytophthora infestans. 



It was concluded that Solanum Maglia of Schlechtendahl, generally known 

 as Darwin's potato, afforded the best prospect of success in the direction, since 

 this species does not appear to suffer from the disease in its indigenous habitat 

 in the low-lying swampy soil of the Chonos Archipelago, whereas the ordinary 

 potato is practically destroyed by the fungus on wet soils in damp seasons. 



On August 6th, 1886, I obtained tubers of Solanum Maglia from a plant 

 growing in the gardens at Kew, the tubers being dug up in the presence of Mr. 

 Baker and myself. 



(Plate 1. Flowers, foliage, &c., of Solanum Maglia, Schlecht., drawn from 

 living specimens grown at Reading.) This species, so far as my experience goes, 

 does not produce fertile seeds when pollinated with its own pollen : although 

 it blooms very freely, the flowers drop off prematurely. Many hundreds of attempts 

 were made to fertilize Maglia flowers with the pollen from cultivated potatoes, 

 but in one instance only was a hybrid seedling obtained, the latter being the 

 produce of a cross made in July, 1887. 



The hybrid, which has been cultivated continuously during the last 20 years, 

 has smooth tubers nearly white in skin (the tubers of Solanum Maglia are a dull, 

 dark purple colour), with leaflets more pointed than those of cultivated potatoes. 



In addition to experiments with Solanum Maglia, crosses were attempted with 

 Solanum Jamesii, but from none of these were seedlings obtained. 



Resembling Solanum Maglia in its general refusal to set " seed " either when 

 pollinated with its own pollen or with that from other species, is Solanum 

 Commersonii of Dunal. 



(Plate 2. Solanum Commersonii, Dun., white-flowered form, foliage, flowers, 

 &c.) Two forms of this species are known ; one bearing lilac flowers and 

 corresponding both in this and in all other respects with Dunal's description, and 

 the other very similar to it but bearing white flowers. In both forms the jessamine- 

 like scent of the flowers is very noticeable. Of the violet-flowered form I have had 

 very many tubers collected in a wild state in Uruguay, and Professor Archeavaleta 

 of Montevideo assures me that there is no other form to be found in a wild state 



* See Journ. Linn. Soc., Bot. vol. xx. (1886) pp. 489-507. 



