Roijal Botanical Society of Edinburgh. 157 



ROYAL BOTANICAL SOCIETY OF EDINBURGH. 



The Society met on Thursday evening (March 11th) in the 

 Royal Institution, Dr. Greville in the chair. 



Mr. Edward Forbes read a communication on the specific value 

 of the appendages of the anthers in the genus Viola. 



Mr. Forbes commenced by stating, that in some plants a particu- 

 lar form of the leaf or other appendage might be the same in all the 

 species, while in other plants this form might only be similar in a 

 few species. In the case of the genus Viola, the antherine append- 

 ages or nectaries have generally been regarded as of generic im- 

 portance only. By comparing the nectary of a Pansey with that of 

 a Dog-violet, a difference will be observed of specific, or at least 

 sectional importance. In order to ascertain the value of this cha- 

 racter, he had examined above seventy species of Violets, chiefly 

 from the herbarium of Dr. Greville. He found three diflferent forms 

 of nectaries. The most common is lancet-shaped, which prevails 

 among the allies of Viola canina and Viola odorata. The next is of 

 a linear form, and prevails chiefly amongst the Pansies, V. lutea, 

 etc. The third is rotund, a rare form, but which may be seen in 

 the Viola palustris. These nectaries are to be found in the spur of the 

 flower, which varies in form according to the shape of the nectary. 

 When the nectary is lancet-shaped, the spur is generally thick in 

 proportion to its length, and very blunt, being shortest in those 

 species which have the nectaries broadest. The rotund nectary is 

 generally associated with a short round spur, and the linear with a 

 slender spur, often of great comparative length. The colours of 

 Violets have also some relation to the forms of the nectaries. In 

 this genus, blue, yellow, purple and white are the colours seen. 

 The blue may again be divided into purple-blue and sky-blue, each 

 passing into white. The purple may also pass into white, but the 

 sky-blue never does. These distinctions are of importance in the 

 investigation of nearly allied species, such as Viola canina and Viola 

 montana. In the one case the yellow passes into pink, and in the 

 other into purple. White is rarely the normal colour of a Violet. 

 The lancet-shaped nectary is chiefly associated with blue flowers, 

 sometimes with the yellow passing into white ; but never with the 

 yellow passing into purple, they having always linear nectaries. 

 The Violets which are normally white derived from blue have always 

 lanceolate or rounded appendages. Mr. Forbes also pointed out the 

 relation of the nectary to the leaf, to the bractea or stipula, and 

 also to the stem. By considering these, along with the colour and 

 geographical distribution, he thought a very natural arrangement of 

 this extensive genus might be made, and which would greatly facili- 

 tate the distinction of species. 



The next paper was upon the botanical characters of the British 

 Oaks, by Dr. Greville. The author stated that he had paid great 

 attention to the distinctive characters of the oaks for the last three 

 years, and his investigations had led him to believe that the usual 

 specific distinctions were not correct. Thus he found that the 

 Quercus sessilifiora in one situation might have a very short flower- 

 stalk, and in another a very long one ; and the same was the case 



