142 A NEW EVENING PRIMROSE. GATE8. 



Oe. biennis^. It is certain that a great many more clearly- 

 defined species remain to be described from the North Ameri- 

 can continent. But the characters of these plants are so 

 numerous and they are so often imperfectly expressed in 

 the wild condition, that adequate studies and descriptions 

 can only be made from the plants by cultivating them, in 

 which condition their characters are fully expressed. Many 

 studies of this kind are now being made, with the result that 

 our knowledge of the genus Oenothera, the distribution, 

 variability and characters of the species, is rapidly becoming 

 more accurate and detailed. 



The majority of the forms occupying the middle and 

 eastern part of the continent agree with Oe. biennis L. in 

 having petals about 20-25 mm. in length, though forms 

 with larger and smaller flowers also occur. North of this 

 area, in a zone extending in a general sense from Maine and 

 Nova Scotia to Manitoba and passing through northern 

 Ontario, occur forms having smaller flowers. Certain of these 

 forms, related to Oe. muricaia L., have been briefly charac- 

 terized elsewhere.- Here I wish to describe a species from 

 No-va Scotia having small flowers as in Oe. muricata but 

 clearlj'^ requiring delimitation as a distinct form. The descrip- 

 tion is as follows: 



Oenothera Norae-Scrdiae sp. nov. 



Diameter of mature rosette (maximum) 48 cm., leaves 

 smooth or slight!}^ crinkled, elliptical or oblanceolate to 

 nearly spatulate, relatively broad and rather broad pointed, 

 about 25 cm, long and 56 mm. greatest width, margin ol)- 

 scurely repand-denticulate, narrowed below to petiole, midrib 

 usually pink above and more or less pink beneath, leaf finely 

 puberulent on both faces (Fig. 1). 



1 For a resume of these forms and their taxononiic history, see Gates. The Mutation 

 Factor in Evolution, with particular reference to Oenothera, chap. ii. MacMillan, 1915. 



1 Op. cit.. pp. 2.3-26. 



