No. 587] SHORTER ARTICLES AND DISCUSSION 



703 



Cultures of pratincola and. nummularia should be grown from 

 germinations established experimentally to be complete, with 

 records of the residue of sterile seed-like structures, and the two 

 forms should be crossed with the purest CEnothera known to 

 determine whether or not the F t hybrid generations are uniform. 

 Should F x hybrid generations consist of distinct classes we would 

 be justly suspicious of the purity of the stock. 



A second paper of Bartlett 2 describes a series of cultures of 

 CEnothera stenomeres, a cruciate-flowered species from Mont- 

 gomery County, Maryland. Two sharply marked new types were 

 produced by the typical form of the species, gigas represented by 

 one specimen with 28 chromosomes, and lasiopetala with hairy 

 petals. The gigas plant appeared in the F 4 generation of a line of 

 stenomeres. The peculiarities separating it from stenomeres are 

 similar to the distinctions between Lamarckiana and its deriva- 

 tive gigas. Thus both gigas forms are more persistently biennial 

 in habit than their parents, both have thicker, broader leaves, 

 stouter stems, larger buds, thicker fruits, 4-lobed pollen grains, 

 and twice as many chromosomes. A progeny of 63 individuals 

 from the original gigas plant consisted of 54 typical gigas, 6 

 narrow-leaved variants, and 3 "secondary mutations"; the form 

 thus, as with the gigas from Lamarckiana, produces a varied off- 

 spring. Two of the "secondary mutations" were dwarfs and one 

 had the characters of lasiopetala, hairy petals, and in addition 

 certain of the stamens were also hairy. 



Lasiopetala was noted in an F 3 generation and also in two cul- 

 tures of an F 4 ; it is of infrequent occurrence, only 5 plants in all 

 being observed. The plants formed persistent rosettes (steno- 

 meres being annual) and only one branch produced flowers, these 

 with hairy petals. The pollen of lasiopetala is 40-50 per cent, 

 perfect ; that of stenomeres 60-80 per cent. An F 1 progeny of 

 116 plants from selfed lasiopetala gave 60 per cent, typical 

 stenomeres and 40 per cent, lasiopetala, thus behaving like 

 CEnothera lata and O. scintillans in throwing their parent form 

 Lamarckiana. 



Of these two new types derived from O. stenomeres the gigas 

 plant is remarkable as being another of the very few Oenotheras 

 discovered with the quadruploid number of chromosomes (28) ; 

 triploid forms usually named semigigas have been described from 

 a number of lines. The hairiness of the petals in lasiopetala is 



2 Bartlett, H. H., "The Mutations of CEnothera stenomeres," Amer. 

 Jour. Bet., Vol. II, p. 100, 1915. 



