Wild Forms and Species of Tuber-bearing 1 Solanums. 



The pollen-grains of the white-flowered plants of 1908, like the one white- 

 flowering plant of 1907 already alluded to, are elliptical like those of the lilac- 

 flowered parent, while those of the lilac-flowered seedling are irregular and polygonal 

 in form, corresponding closely in these respects with pollen-grains of the cultivated 

 potatoes. These are illustrated in Plate 12, and on Plate 11 is figured one of the 

 lilac-flowered seedlings raised by selfing flowers of Solanum etuberosum in 1907, 

 with drawings of its irregular pollen-grains. 



From the uniform character and shape of its pollen-grains, it would appear 

 that Solanum etuberosum is a primitive specific form, since it agrees in this respect 

 with admittedly wild species of tuber-bearing Solanums. Moreover, in the great 

 variability of its seedlings it closely resembles the cultivated potato. These facts, 

 I think, point to the conclusion that Lindley's Solanum etuberosum may probably 

 be the parent form of the cultivated potato of to-day. 



EXPLANATION OF THE PLATES. 



The figures on the Plates were all drawn from specimens growing in the 

 Reading Trial Grounds. 



PLATE 1. 

 Solanum Mnglia, Schlecht. 



A. Inflorescence and upper leaves, . 



B. Flower showing anthers, x 2. 



C. Flower showing calyx, x 2. 



D. Flower, side view x 2, showing cleft 



stigma. 



E. Flower section, x 2, showing cleft 



stigma. 



F, G, H. Cymes with flowers removed, . 

 J. Largest leaf on examples examined, J. 

 K. Pollen, x 300. 



PLATE 2. 

 Solanum Commersonii, Dun. 



(White-flowered form.) 



A. Inflorescence and upper leaves, large 



lower leaf behind, . 



B. Cymes with flowers removed, . 



C. Flower-bud, x 2. 



D. Hairs from tips of petals, x 50. 



E. Hairs from limb of corolla, x 50. 



F. Pollen, x 300. 



G. Self-fertilized berries, 

 H. Seed, x 2. 



J. Cross-fertilized berries, 



K. Sections of do., }. 



L. Seed, x 2. 



PLATE 3. 



" Solanum Commersonii ' Violet,' " Labergerie. 



A. Inflorescence and upper leaves, large 



lower leaf behind, \. 



B. Cyme with flowers removed, \. 



C. Hairs from tips of petals, x 50. 



D. Hairs from limb of corolla, x 50. 



E. Pollen, x 300. 



F. Berry, . 



G. Section of berry, }. 

 H. Seed, x 2. 



PLATE 4. 

 Paulson's " Blue Giant " Potato. 



A. Inflorescence and upper leaves, large 



lower leaf behind, . 



B. Cyme with flowers removed, |. 



C. Hairs from tips of petals, x 50. 



D. Hairs from limb of corolla, x 50. 



E. Pollen, x 300. 



F. Berry, \. 



G. Section of berry, }. 

 H. Seed, x 2. 



