1902] VEGETATION AT WOODS HOLE 441 
shore where the danger of burial was greatest. Explanation of 
this fact was found by digging, for the plant possessed running 
stems, penetrating the sand in all directions in a manner similar 
to sand binders, and like them was able to grow out as fast as 
buried. Limnanthemum and Lobelia have no runners, and so 
are driven to the zone beyond. 
At the south end of Long pond, the slopes surrounding are of 
Fic. 2.—West end lake. 
@ such acontour that washings would be swept toward a certain 
Portion of the shore line. Moreover, the suf 
Portion has been broken by cutting a road, and silt is brought in 
Seat quantities. Where this material reaches the shore line a 
‘andy beach is formed, and from the beach it has advanced into 
the pond some 30 meters as a submerged delta. The peers 
(fg. 3) may aid in making the case clear. 2 ee 
y elta is shaded ; the sandy beach represen 
ae ‘ow the Limnanthemum- Lobelia zone (indi _ aS ad 
- les) follows closely the outline of the submerge 
‘he Euthamnia zone on the shore (outlined by the one s 
Nettup ted by the sandy beach. The fa ct 15 is that the oo 
icated by the sma 
face near this a 
