Observations on Asarum europaeum and its 
Mycorhiza. 
BY 
E. J. SCHWARTZ, M.A., B.Sc., F.L.S. 
King's College , London. 
With Plate LXXII. 
SARUM europaeum , the Asarabacca, is said to form our sole native 
jTl representative of the Natural Order Aristolochiaceae ; it is, however, 
questionable as to whether its claims to be indigenous are justifiable. The 
plant was formerly cultivated for medicinal purposes, a volatile oil, asarol, 
being extracted from it, and it is probable that the few plants found wild in 
this country are either ‘ escapes or the descendants of ‘ escapes ’, from 
plants so cultivated. The plant, which in its wild state grows in woods and 
damp, shady places, consists of a branched rhizome which creeps along or 
near to the surface of the ground, each branch bearing annually two kidney- 
shaped green leaves with long petioles. These leaves are protected in the 
bud by a few scale leaves also borne by the rhizome. From the under surface 
of the rhizome spring a number of adventitious roots, which with their 
branch roots form the root-system of the plant. The roots penetrate the 
soil to a depth of from six to eight inches. The flowers resemble those of 
other members of the Aristolochiaceae in having a three-lobed calyx and 
twelve stamens, the latter being united to the style to form a gynostemium, 
thus showing some similarity to a monocotyledon, the similarity being 
heightened by the existence in the roots of an endotrophic mycorhiza, of 
a character somewhat resembling that described by Groom (.2) as being 
found in the roots of Thismia Aseroe. The plant, however, is an undoubted 
dicotyledon, as is evident from the anatomy of its rhizome, and from the 
possession of two cotyledons by the seedling plant. The affinities of the 
order are, however, very obscure ; it has been placed with the Santalaceae, 
Loranthaceae, and Rafflesiaceae to form the class Hysterophyta. 
The material used in this investigation was obtained from a small 
group of plants growing in the garden of my home at Sevenoaks.- These 
plants were uprooted in the early autumn of 1911, and portions of the roots 
[Annals of Botany, Vol. XXVI. No. CIII. July, 1912.] 
3 E 
