The plant life found along the beach follows zonation and exposure patterns like those that govern the distribution of animals. Although there are many species of marine plants, a few of the most common are described here. Algae, or seaweeds, are classified on the basis of the photosynthetic pigments they use. Green algae use chlorophyll like terrestrial plants. The red and brown algae also use chlorophyll, but its color is masked by other photosynthetic pigments.
The most common brown seaweed is rockweed (Fucus), which is found attached to rocks throughout the middle intertidal zone. Gas-filled bladders at the tip of each branch help keep the plant floating near the surface when the tide is in, and thus increases the amount of light available for its energy needs. Light is filtered out rapidly as it passes through water. Rockweed also secretes a mucus-like substance which helps keep it moist during low tide.
In the lowest reaches of the intertidal zone, you’ll find a few large brown algae which belong to the group referred to as kelp (Alaria, Costaria and Laminaria). These are perhaps best observed attached to the floats at the main dock. At the entrance to Bartlett Cove, at the south tip of Lester Island, and just off Halibut point there are large beds of these kelps. One of the kelps seen in these beds is the bull or bulb kelp (Nereocystis luetkeana). One of the fastest growing plants on earth, this kelp may grow as much as six inches in length a day.