1^1"] Goodspeed-Claiisen : F^ Species Hybrids in Nicotiana 303 



H33— N. sylvestris (U. C. B. G. 69/07 and 107/01; ef. Setchell, 

 1912, p. 29) X N. Tabaeiim var. macrophylla purpurea 

 (U. C. B. G. 25/06. ibid., p. 10). 



H36— N. (Tabacuin) angustifolia (U. C. B. G. 68/07, ibid., p. 

 9) X N. sylvestris. 



H38— N. Tabaeum var. macrophylla (U. C. B. G. 22/07, ibid., p. 

 8) X N. sylvestris. 



H40— N. Tabacmn var. ealycina (U. C. B. G. 110/05, ibid., p. 

 6) X N. sylvestris. 



H142— N. Tabaeum "Maryland" (U. C. B. G. 78/05, ibid., p. 

 5) X N. sylvestris. 



H179— N. Tabaeum ''Cuba" (U. C. B. G. 200/14, Goodspeed, 

 1915) X N. sylvestris. 



With the exception of the last, these hybrids and their reciprocals 

 have been remade on numerous occasions during the past tive years 

 with entirely corresponding results in every case. 



A few general statements might be made concerning the above 

 hybrids and their parents before taking up the more detailed individ- 

 ual descriptions. In the first place, sylvestris is characterized by a 

 limited perennial habit, and plants in the garden have come up a 

 number of years in succession from what appear to be adventitious 

 buds produced at the base of the stem. In other words, the parts 

 above ground die down during the winter and entirely new shoots 

 come up from the surface of the ground in the spring. Such a limited 

 perennial habit is unusual in the case of an herbaceous tobacco and 

 is in general peculiar to such arborescent species as N. tnmentosa 

 and N. glauca. The sylvestris parent is also distinguished from the 

 Tabaeum varieties by its very slow rate of early growth, as a conse- 

 quence of which the rosette stage of development is so long maintained 

 that when sown late the plants in our cultures pass the entire season 

 in rosette and do not flower until the following growing season. 

 Finally we may note, as a character distinctly peculiar to sylvestris, 

 the strikingly pendent habit of the flowers on the dense inflorescences, 

 a habit maintained from the late bud stage up to or slightly after 

 anthesis. This sylvestris character is well shown in plate 40, figure 2, 

 and perhaps more than any other superficial character sets this species 

 apart from all other species and from the F^ hybrids under consider- 

 ation liere. 



With reference to these more general characters peculiar to syl- 

 vestris it is to be noted that the Fj hybrids are alike in exhibiting. 



