Benson.—Root Parasitism in Exocarpus. 
677 
DESCRIPTION OF THE FIGURES IN PLATE LV. 
Illustrating Dr. Margaret Benson’s paper on Exocarpus. 
Figures A and 1-3. 
Fig. A. A seedling plant of Exocarpus cupressiformis , showing the form of the early leaves, 
which decrease in size on the lateral branches. The roots show many haustoria, which are 
indicated by the letter H. A 1 represents a foreign root to which the Exocarpus root is attached. To 
the right of the seedling are some twigs from an adult plant showing the switch-like habit and 
the ‘ Native Cherry ’ fruits. (Slightly reduced.) 
Fig. 1. A camera drawing of a Rhinanthaceous haustorium upon a Thesium root. Th = the 
Thesium root; H = the haustorium attached to the neck, N. No granules were present in the 
phloeotracheide head, Ph. Note the axile row of phloeotracheides continuous from the head to 
the surface of contact with the host, x 87. 
Fig. 2. A camera drawing of a Thesium haustorium, H , attached to a Thesium root, Th. The 
neck, N , shows continuity by means of short tracheides with the diarch Thesium root, R. The 
surface of contact is only faintly distinguishable owing to the almost complete fusion of the two 
structures. X 87. 
Fig. 2 a. An enlarged drawing of the left-hand phloeotracheide of the above figure, showing its 
insertion into a medullary ray of the host. M = the medullary ray cell containing starch grains ; 
Tr = a tracheide of the host root; Ph — the phloeotracheide with its non-striated tip inserted into 
the ray. x 345. 
Fig. 3. An enlarged drawing of an ordinary phloeotracheide from a haustorium of Thesium. 
Strands which are thought to be protoplasm are seen in continuity with the living matrix, which 
contains spherical granules, G, of amylodextrine. Two thin-walled, nucleated cells, N, abut on the 
phloeotracheide. x 345. 
