Phylum Ochrophyta

The brown seaweeds have recently been grouped into a single large division (=phylum) with other unicellular golden or brown-pigmented algae (e.g. diatoms, chrysophytes). This is based on the fine structure of their flagella and chloroplasts, among other characteristics. Brown seaweeds possess an accessory photosynthetic pigment called fucoxanthin, which gives them their golden-brown color. These large, productive seaweeds are important components of nearshore marine communities, especially in temperate latitudes. The kelps (Order Laminariales, including Macrocystis) have a complex life history that alternates between a large spore-producing phase and a microscopic gamete-producing stage. 1500-2000 living species.

Class Phaeophyceae (Brown Seaweeds)

Class Phaeophyceae (Brown Seaweeds)

Order Fucales

Stephanocystis osmundacea (Turner) C. Agardh
Phylum Ochrophyta, Class Phaeophyceae, Order Fucales, Family Sargassaceae

Perennial thallus with short stipe; flat stiff blades with faint midrib; margins pinnately lobed. Bushy reproductive fronds grow seasonally from tips of perennial blades, buoyed by many small gas-filled pneumatocysts (floats). Reproductive fronds begin to grow in winter, reach water's surface in mid-spring, then senesce & slough off by late summer.

Abundant, on rocks in shallower areas of kelp forest, usually most abundant on shallower margins of forest.

Geogr. Range: Oregon to Baja
Synonyms: Cystoseira osmundacea
Similar species: other local fucoids such as Fucus and Silvetia are intertidal rather than subtidal.

Order Desmarestiales

Desmarestia ligulata (Lightfoot) Lamouroux
Phylum Ochrophyta, Class Phaeophyceae, Order Desmarestiales, Family Desmarestiaceae

Acid kelp; thin straplike blades with obvious midrib; main axes <1 cm wide with more than 2 orders of side branches proliferating from each main axis. Contains sulfuric acid in vacuoles as a deterrent to grazers.

Common but patchy & sporadic; on rocks, particularly in areas recently disturbed by winter storms.

Geogr. Range: Alaska to San Diego; widely distributed in N. hemisphere
Synonyms: Desmarestia ligulata var. ligulata in part
Similar species: Desmarestia munda has wider blades with only 1 or 2 orders of side branching.

Desmarestia munda Setchell & N.L. Gardner
Phylum Ochrophyta, Class Phaeophyceae, Order Desmarestiales, Family Desmarestiaceae

Acid kelp; straplike blades with conspicuous midrib; main axes >1 cm wide with only 1 or 2 orders of side branches proliferating from each main axis. Contains sulfuric acid in vacuoles as a deterrent to grazers.

Common but patchy & sporadic; on rocks, particularly in areas that are frequently or recently disturbed (e.g. by winter storms).

Geogr. Range: Alaska to San Diego; widely distributed in N. hemisphere
Synonyms: Desmarestia ligulata var. ligulata in part
Similar species: Desmarestia ligulata has narrower blades with >2 orders of side branching giving it a bushier appearance.

Desmarestia foliacea V.A. Pease
Phylum Ochrophyta, Class Phaeophyceae, Order Desmarestiales, Family Desmarestiaceae

Unbranched broad thallus thick & more substantial than other acid kelps; conspicuous axial midrib with lateral veins branching from it (specimen in photo is very tattered). Contains sulfuric acid in vacuoles.

Sporadic; on rocks, particularly in more wave-exposed or deeper sites or those recently disturbed by winter storms.

Geogr. Range: Monterey & Carmel Bays
Synonyms: Desmarestia ligulata var. firma
Similar species:

Order Laminariales

Macrocystis pyrifera (Linnaeus) C. Agardh
Phylum Ochrophyta, Class Phaeophyceae, Order Laminariales, Family Lessoniaceae

Giant kelp to 45 m; numerous fronds growing from conical holdfast; fronds composed of long cylindrical stipe to 10 mm diameter, with gas-filled floats attached along its length, each with a flattened corrugated blade growing from its apex. Forms a conspicuous floating surface canopy whose thickness varies greatly with season & location.

Abundant, on rocks at depths to 30 m, depending on water clarity, sedimentation, nutrient availability.

Geogr. Range: SE Alaska to northern Baja, temperate waters of S. hemisphere
Synonyms:
Similar species: Macrocystis integrifolia occurs in the low intertidal & its holdfast is straplike rather than conical.

Nereocystis luetkeana (Mertens) Postels & Ruprecht
Phylum Ochrophyta, Class Phaeophyceae, Order Laminariales, Family Lessoniaceae

Bull kelp, single stipe to 35 m with large terminal float from which grow 30-60 staplike blades, each ~4 m long.

Common, especially in wave exposed areas & on margins of Macrocystis forests.

Geogr. Range: Alaska to central California
Synonyms:
Similar species:

Dictyoneuropsis reticulata (D.A. Saunders) G.M. Smith
Phylum Ochrophyta, Class Phaeophyceae, Order Laminariales, Family Lessoniaceae

Thallus to 95 cm; clusters of many broad crisp blades with rectangular reticulations; blades golden brown, each with a flat wide midrib; new blades added by longitudinal splitting along midrib, so recently formed blades have rib displaced toward one edge.

Moderately common, on rocks in more sheltered areas within kelp forests.

Geogr. Range: British Columbia to north Channel Islands
Synonyms:
Similar species: Dictyoneurum californicumis very similar, but its blades are narrower, usually lack a midrib and occurs in sites with stronger water motion. Molecular data suggest these two species are eco-morphs of a single species.

Dictyoneurum californicum Ruprecht
Phylum Ochrophyta, Class Phaeophyceae, Order Laminariales, Family Lessoniaceae

Thallus 50-200 cm; clusters of brown, crisp, straplike blades with irregular reticulations but usually lacking distinct wide midrib.

Moderately common, on rocks in more exposed areas.

Geogr. Range: British Columbia to north Channel Islands
Synonyms:
Similar species: Dictyoneuropsis reticulata has broader blades with a distinct flat midrib, but otherwise is very similar. Molecular data suggest these are different habitat-induced morphs of the same species.

Costaria costata (C. Agardh) D.A. Saunders
Phylum Ochrophyta, Class Phaeophyceae, Order Laminariales, Family Laminariaceae

Thallus with single stipe giving rise to a single broad blade with 5 longitudinal ribs, to 35 cm wide & 50 cm long.

Moderately common, on rocks; low intertidal and shallow subtidal.

Geogr. Range: Alaska to southern California, also Japan
Synonyms:
Similar species: Dictyoneuropsis / Dictyoneurum have multiple straplike blades; neither's blades have 5 distinct longitudinal ribs.

Laminaria setchellii P.C. Silva
Phylum Ochrophyta, Class Phaeophyceae, Order Laminariales, Family Laminariaceae

Thallus with single stiff cylindrical stipe to 150 cm tall; stipe flattens at top and spreads into a single, deeply divided blade which is smooth and rubbery in texture.

Common on rocky substrate as an understory layer in wave-exposed kelp forests; also grows in very low intertidal and shallow subtidal zones.

Geogr. Range: Alaska to Baja
Synonyms: Laminaria dentigera
Similar species: Pterygophora californica has a longer flattened area at the top of its stipe from which numerous separate lateral blades grow. Eisenia arborea has a y-shaped bifurcation at the top of its stipe with numerous blades growing from each branch.

Pleurophycus gardneri Setchell & Saunders
Phylum Ochrophyta, Class Phaeophyceae, Order Laminariales, Family Laminariaceae

Thallus with single stipe to 50 cm tall & a single broad blade up to 150 cm long with wide midrib where spore- producing sorus forms seasonally; blade surface adjacent to midrib ruffled or puckered. Stipe perennial but blade is annual (grows from Feb until July, begins to slough in Aug & is excised by Dec).

A deep-water kelp (usually 20-40 m) in central California, but occurs in intertidal zone in Pacific NW.

Geogr. Range: Alaska to central California.
Synonyms:
Similar species: Pterygophora californica has a flattened area at the top of its stipe from which numerous lateral blades grow. Stipe of Eisenia arborea bifurcates at the top with numerous blades growing from each branch; Laminaria setchellii lacks a midrib & its blade is divided.

Pterygophora californica Ruprecht
Phylum Ochrophyta, Class Phaeophyceae, Order Laminariales, Family Alariaceae

Thallus with single stiff cylindrical stipe to 1.5 m tall; top quarter of stipe flattened with 5-10 lateral blades on opposite edges and a long terminal blade with a broad pale stripe (not midrib) running up the middle.

Abundant on rocky substrate in wave exposed sites, forming an understory layer beneath Macrocystis canopies.

Geogr. Range: British Columbia to Baja
Synonyms:
Similar species: Laminaria setchellii also has a single tall stipe, but lacks lateral blades on upper stipe. Eisenia arborea has a y-shaped bifurcation at the top of its stipe with numerous blades growing from each branch.

Eisenia arborea Areschoug
Phylum Ochrophyta, Class Phaeophyceae, Order Laminariales, Family Alariaceae

Thallus with single stiff cylindrical stipe to 1.5 m tall with y-shaped bifurcation at the top; numerous blades grow from each tip; blades corrugated & toothed in larger individuals. Plants change morphology drastically as they grow.

Common at certain wave-exposed sites in Monterey region; on rocks as understory beneath Macrocystis canopy.

Geogr. Range: disjunct pattern: British Columbia, Monterey Bay region, southern California to Baja
Synonyms:
Similar species: Pterygophora californica and Laminaria setchellii lack y-shaped bifurcation at top of stipe.

Egregia menziesii (Turner) Areschoug
Phylum Ochrophyta, Class Phaeophyceae, Order Laminariales, Family Alariaceae

Long straplike thallus 2 cm wide with numerous proliferous blades and small gas-filled floats along opposite edges.

Abundant on rocks in low intertidal and very shallow subtidal in Monterey region; occurs at kelp forest depths in southern California.

Geogr. Range: Alaska to Baja
Synonyms:
Similar species:

Order Ectocarpales

Coilodesme californica (Ruprecht) Kjellman
Phylum Ochrophyta, Class Phaeophyceae, Order Ectocarpales, Family Cordariaceae

Thallus fingerlike hollow sack 25-35 cm long; light olive tan.

Common, but seasonal as an epiphyte on reproductive fronds of Stephanocystis osmundacea.

Geogr. Range: British Columbia to Baja
Synonyms:
Similar species: