VEGETATION OF THE STRAND. 589 



divisions. Schimper divides the ocean strand into three parts: 

 ist, the fore-shore (Schorre), the area covered by the tide be- 

 tween ebb and flow, and in sandy shores devoid of vegetation; 

 2d, the mid-shore, above the flood line of the tide; 3d, the dunes y 

 the sand-hills toward the interior. A different division is made 

 of the strand formations of Lake of the Woods by MacMillan 

 as follows: 



i st. The front strand, being that part of the strand next the 

 water, upon which the surf washes during the ordinary winds of 

 the season. 2d. The mid-strand, an area parallel with this, but 

 farther up on the beach and acted upon by the surf at greater 

 intervals during very high winds. At Lake of the Woods these 

 high winds are believed by MacMillan to occur once in several 

 years. 3d. The back strand. This is developed by the activity 

 of the wind rather than by the ice or surf, and may represent in 

 some cases a higher level of the lake. 4th. Strand pools, hollows 

 where water accumulates either from surf or from rains. 5th. 

 Dimes, hills of sand formed by the wind driving the sand, which 

 is caught and held by plants. Some use a slightly different 

 terminology, as follows: 



i st. Lower beach ( = front strand); 2d, middle beach ( = mid- 

 strand); 3d, upper beach ( = back strand); and 4th, dunes. 



1081. The lower beach, or front strand. This being fre- 

 quently washed by the surf prevents the permanency of any 

 vegetation. Seeds of plants may germinate, but waves wash 

 the seedlings away. The only plants which develop here are 

 those which can pass through the period of growth and fruiting 

 in a short while. Thus lower algae, especially members of the 

 Cyanophycea (blue-green algae), are often found here in small 

 pools which' are fed by the surf. If the water remains quiet 

 for some time, the pool may dry, but the plants are tided over 

 the dry period by their spores (Nostoc, Anabaena, Oscillatoria, 

 Lyngbya, etc.). 



1082. Middle beach. This corresponds to mid-strand, and 

 represents the zone acted upon at longer intervals by the surf, 

 generally during the winter at the time of higher winds. The 



