AMERICAN 
JOURNAL OF BOTANY 
Vol. IV March, 191 7 No. 3 
MATROCLINIC INHERITANCE IN MUTATION CROSSES OF 
OENOTHERA REYNOLDSIP 
Carl D, La Rue and H. H. Bartlett 
Introduction 
This paper is concerned primarily with the pecuHar type of in- 
heritance exempHfied among the mutations of Oenothera Reynoldsii, 
a species elsewhere described as showing the phenomenon of "mutation 
en masse,'' or mass mutation. It has been found that the mutations 
characteristic of mass mutation in this species, when crossed among 
one another, or with the parent form, give crosses which in general 
conform exactly to the t^^pe of the pistillate parent, quite regardless 
of which way the cross may have been made. 
De Vries^ has shown that in Oenothera Lamarckiana, the most 
thoroughly studied of the evening-primroses, the total number of 
mutations lies in the neighborhood of 2.2 percent. Certain mutations 
from Oe. Larmackiana are themselves more mutable than their parent. 
Thus Oe. lata produces twice, and Oe. scintillans three times as many 
mutations as Oe. Lamarckiana itself. Before the discovery of mass 
mutation in Oe. Reynoldsii and Oe. pratincola, a form was considered 
highly mutable if its progeny contained as many as five or six percent 
of mutations. Aside from Oe. Lamarckiana, however, only one species, 
Oe. biennis, had been extensively grown for the detection of mutability, 
1 Prior to 1915 the work upon which this paper is based was carried on by the Office 
of Physiological and Fermentation Investigations, Bureau of Plant Industry, U. S. 
Department of Agriculture, and since then by the University of Michigan. Pub- 
lished by permission of the Secretary of Agriculture. 
Papers from the Department of Botany of the University of Michigan, no. 155. 
2 De Vries, Gruppenweise Artbildung, p. 329 et seq. 
[The Journal for February (4: 53-118) was issued Feb. 17, 191 7.] 
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