MICHIGAN ACADEMY OF SCIENCE. 
49 
THE ASSOCIATIONS IN UN BURNT AREAS. 
The Plankton Association. 
The free swimming and floating algae and protozoans which constitute 
the plankton were not investigated. 
The Ohara Association. 
This association of submerged rooted aquatics is the first in the lake 
series of genetic succession. It occurs normally in the deeper water 
of the various lakes in the region. It may be obtained by dredging 
or by collecting the plants which are uprooted and washt ashore dur- 
ing storms. 
On account of the extreme openness of the aquatic vegetation in these 
lakes, Ohara also grows in shallow water — almost up to the shore line in 
certain bays where there is no higher vegetation to prevent its develop- 
ment. For this reason, also, Ohara exists as a relic in every aquatic 
association. With the Ohara , MyriophyUum spicatum and Eloclea cana- 
densis may be frequently associated as secondary species. 
The Potamogeton Association. 
This association of submerged, rooted aquatics develops in shallower 
water than Ohara normally does, but it can not grow in as shallow 
water as Oluira will under favorable conditions. As this association is 
usually developt in Douglas Lake, fairly dense patches of vegetation are 
strung along the drop-off, extending shoreward until the water is some- 
what over a foot in depth, unless stopt by other vegetation. This asso- 
ciation is partial to the sheltered bays and exists only in small isolated 
patches in the open lake, where it is subject to severe wave action. 
This is shown in Plate 6b. On account of the openness of the aquatic 
vegetation that is prevalent in this region, the species of this association 
readily remain as relics in the succeeding associations. 
List of the Species of the Potamogeton Association : 
DOMINANT SPECIES. 
Potamogeton natans. 
Po 1 a in o get on rich ardsonianus. 
Pot a mogeton zosterifo li us. 
Pot a mogeton pectina Pus. 
Potamogeton lieteroplryll us. 
forms myriophyllus and 
Po tam ogeton fil i formis. 
Potamogeton luce ns. 
Potamogeton strict ifoli us. 
Xaias ffexilis. 
demcrsum. 
Ceratophyllnm 
maxim us. 
SECONDARY SPE( TES. 
Elodca canadensis. 
Va ll i sner i a spi ra Us. 
Myrioph ylluni spicatum. 
