216 MASS MUTATIONS AND TWIN HYBRIDS OF 



of the two reciprocal crosses were the same and constituted one 

 uniform lot. In June the absence of velutina was clear; the hybrids 

 of ochracea x Cockerelli had broad leaves (6—7 cm.) and were stout 

 green plants, whereas those of the reciprocal cross were still pale. 

 I compared them with the hybrids of 0. grandiflora x Cockerelli 

 and with those of 0. grandiflora lorea x Cockerelli which grew quite 

 near to them. In the beginning of August they began to flower 

 and almost all of the plants of both cultures reached this phase 

 before the end of the month, reaching a height of 1.50 m. They 

 were uniform groups and in all respects like the laeta of the corres- 

 ponding crosses, with the exception of the paleness of one of the 

 two sets; but this diminished gradually as the summer advanced. 

 The leaves and bracts of the inflorescence were still very broad 

 and flat. There were no specimens like the velutina of the crosses 

 with 0. grandiflora and 0. lorea. 



C. Uniform hybrids 



0. grandiflora x 0. syrticola. — The hybrids derived from the 

 pollen of 0. syrticola (0. muricata) have often the type described 

 as gracilis in my Gruppenweise Artbildung, This is especially the 

 case with those of 0. Lamarckiana, and the hybrids to be described 

 here simply duplicate these latter. I made the cross twice, in 1913 

 and 1914, and had the first generations of 80 and 30 plants in 1914 

 and 1915. From the latter I derived a second generation from two 

 self-fertilized individuals of the first. They were uniform lots when 

 they flowered, embracing 7 and 44 specimens with the slender 

 stature and characteristic foliage and stature of gracilis, but many 

 seedlings had been yellow and died before making their leaves, 

 exactly as in the first generation. In this the uniformity of the type 

 was already evident in the beginning of June, before the full develop- 

 ment of the stems, by the brownish color of the stems and foliage 

 and the narrow, almost linear, leaves. The resemblance to 0. biennis 

 x syrticola increased during the growth of the stems and the develop- 

 ment of the spikes. At the time of flowering the plants measured 

 only 80—120 cm.; their top was curved sideward as in 0. syrticola, 

 the flowers were small and 3—5 of them opened every evening; 

 lobes of the stigma short and thick; leaves narrow, slightly kennel- 

 shaped, and bluish green. It is easily seen that the characters of the 

 father prevailed in the hybrid. 



0. grandiflora x 0. biennis. — This combination corresponds to 



