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234 NOTE ON A PECULIAR TUSSOCK-FORMATION. [Sess. uxxt. 
NOTE ON A PECULIAR TUSSOCK-FORMATION. 
By W. W. Sirs, M.A. 
During a visit to the Isles of Scilly in August 1906, I 
came across a somewhat unusual formation in one of the 
marshes of the main island of St. Mary’s. 
There is a deep depression one mile north cf Hugh Town, 
forming an extensive tract of marsh. This marsh is well 
sheltered from the prevailing winds, and even in dry 
weather remains moist. At the upper end of this marsh 
is a sluggish watercourse—practically the only stream to 
be seen in the group, if we except the large “ drain-cuttings ” 
in the Town Marshes. The area around this watercourse 
is moist and muddy even in the height of summer. In one 
corner of this area I found that Carex paniculata was 
plentiful—a Carex tending to form small tussocks. 
Combined with the Carex, there occurs a quantity of 
Arundo Phragmites and Pteris aquilina, and when these are 
found together the tussock-formation is very considerably 
enlarged. The largest forms recall at once in outline the 
salient features of a tree-fern—there is a stumpy base, 
rising in some cases to four or five feet, and the leaves of 
the above three plants form a large crown at the apex. 
I quote the measurements of two individuals :— 
No. 1. Height of stump 5} feet ; total height 10 feet, cir- 
cumference of stump at thickest 832 feet. 
No. 2. Height of stump 4 feet; girth at 3 feet, 7 feet; 
circumference of crown 12 feet. 
The three plants mentioned are present in varying pro- 
portions—sometimes the Arundo is awanting. But it is 
the presence of the Arundo and the VPteris in the mass 
which, in my opinion, gives the extra size to the clump (for 
several pure Carex paniculaia tussocks are aiso present, and 
these are less than one foot high). The peculiar tree-fern-like 
aspect is also due to the admixture; the bases of the leaves 
of the Pleris and Arundo persist, and clothe the surface of 
the stump as in a Cyathea. The character of the ground” 
must also have its influence, as I did not observe any 
similar growths in the remainder of the marsh-land; the 
conditions at this one spot served to prevent the levelling- 
