1919- Praeger. — Asplenium Adianttmi-nigrmn. 19 



the lamina), which is usually quoted as a character of the 

 variety ; and the development of another characteristic 

 feature, the beautiful satiny lustre, is probably helped by 

 the same cause. Planted in the open, so far as my experience 

 goes, acuUim produces fronds less divided, and showing by 

 their reflexed pinnules and small size dislike of the excess of 

 light. On the contrary var. ohtusum is mostly found in 

 exposed situations, and planted in shade becomes larger 

 and more divided, and may revert for all practical purposes 

 to the type ; but so far as I have had an opportunity of 

 .observing, no change of conditions will induce acutum to 

 abandon its tripinnate character, though its fronds may 

 become congested and their caudate character lost, jwhen 

 grown in sunlight. 



I should like to add that owing to the exigencies of war- 

 time, I have been unable to check some of my references, 

 and to verify some quotations, where the works from which 

 they are taken were not obtainable in Dublin. The same 

 cause prevents my referring at present to the distribution 

 and characters of var. acutiim as found outside Ireland. 

 I have to thank Dr. Scully and Mr. R. A. Phillips for kindly 

 supplementing the material available to me by sending the 

 series of A. A diantum- nigrum and its varieties preserved in 

 their herbaria. 



DESCRIPTION OF PLATE 2. 



1. A. Adiantum-nigrmn var. acutum f. lineare. Coll. Isaac Carroll (without 



locality). National Herbarium. 



2. A. Adiantum-nigyum var. acutum f. ovatum. Snowhill, Co. Kilkenii)^, 



1899. R. LI. Praeger. 



3. A. Adiantum-nigrum var. ohtusum. Foynes, 1902. Miss O'Brien. 



National Herbarium. 



4. A. Adiantum-nigrum type. Graiguenamanagh, Co. Kilkenny, 1898. 



R. LI. Praeger. 



All natural size. 



National Library, Dublin. 



