Lab #5: Phaeophyceae Flashcards
Phaeophyceae Characters
Cell: Eukaryotic
Cell covering: Cell wall composed of cellulose with an outer mucilage layer.
Economically: important mucilages include the alginic acids
Flagella: Spores and gametes flagellated (two flagella: one tinsel and one
whiplash) (heterokont)
Chloroplast: Double membrane with two layers of chloroplast ER, thylakoids in
stacks of two to six, primary pigment is chlorophyll a, accessory
pigments include chlorophyll c, ß-carotene, xanthophylls
(especially fucoxanthin)
Food storage: Laminarin
Level of organisation: All multicellular, ranging from branched filaments to a
parenchymatous thallus with tissue differentiation
Reproduction: Asexual reproduction usually by spores. Life cycle is usually an
alternation of heteromorphic generations (some are isomorphic
and some have gametic meiosis)
Habitat: Almost entirely marine
Ectocarpus (order Ectocarpales)
Morphologically similar to brown algar
Single row of filaments (filamentous)
Often branched
Asexual or sexual
Unilocular or pleurilocular sporangia
Order Fucales Characters
diplontic life cycles
growth in length localized in an apical meristem
complex parenchymatous morphologies
Fucus distichus
Discoid holdfast
dichotomous branching
Diplontic life cycle
Monoecious
Sargassum muticum
Localized apical growth
highly invasive
Order Desmerestiales Characters
heteromorphic alternation of generations with a microscopic gametophyte
trichothallic meristem
large pseudoparenchymatous sporophytes
Genus Desmerestia
Sporophytes may have cylindrical or leafy branches
Growth from a
trichothallic meristem produces a pseudoparenchymatous, uniaxial thallus
Some
species have vacuoles containing sulfuric acid
Desmerestia herbacea
Sulfuric acid in vacuoles
Brown in color
Desmerestia aculeata
No sulfuric acid
Alternate branching
Fine branches
Order Laminariales Characters
a heteromorphic alternation of generations
growth in length localized in an intercalary meristem
complex parenchymatous morphologies
Nereocystis luetkeana
Bull kelp
Float with CO
Outer pigemented meristoderm
Pale long cells is cortex
inner filamentous cells are medulla
Dark patches on thallus are sori
Each sorus has club shaped sporangia stacked between sterile tissues (paraphyses)
Hedophyllum sessile
lacks stipe
important intertidal understory kelp
Alaria marginata
Moderately protected waters with strong currents
Well developed holdfast
Sporophylls at base and long negative blade
Egregia menziesii
Olive green or dark brown
large holdfast
centrally flattened rachis extends from stipe and has many small blades
Many small air bladders
