Phylum: Phaeophyta

Class: Phaeophyceae

Order: Laminariales

Family: Lessoniaceae

Macrocystis integrifolia (Bory)


Description: This plant is one of the largest brown algae, and is deep brown in colour.  It has a flattened, ligulate creeping rhizome, 2-4 cm. wide.  The rhizome is profusely and dichotomously branched, attached closely to the substrate by branched root-like structures that arise from the margins.  Numerous erect main stipes arise from the rhizome; they are slender, up to 1 cm. in diameter and up to 30 m. long.  Leaf-like branches arise at intervals along the stipe; they are flattened, 25-35 cm. long and up to 5 cm. wide with irregularly furrowed surfaces, tapering gradually to the end and abruptly rounded at the base to a spherical to oval float at the point of attachment on the stipe.  The blades are denticulate along the margins.  The terminal blade, located at the apex of the stipe, is split from the base with several new leaf-like branches in various stages of separation


Habitat:  On rocks in the lowermost intertidal and upper sub-tidal zones to a depth of about 4 fathoms; only in areas close to the open ocean, but not exposed directly to heavy surf.


Pacific Coast Distribution:  Alaska to California.

                                                                                      Robert Scagel, 1972


M. integrifolia blade-like branches showing dentate edges, corrugated surfaces and proximal floats

Habit of section of plant that washed ashore to Race Rocks in the summer of 2002 (this species is not native)