Phaeophyta

Outline

Introduction -- marine, complex thallus, mostly diplohaplontic

Thallus morphologies

unicellular

colonial (e.g., filamentous)

pseudoparenchymatous

parenchymatous

The last three occur in the phaeophytes

Cells

Like those of other heterokont algae

also have

characteristic pyrenoids

physodes -- tannin-filled vesicles

characteristic cell walls

• fibrillar component-- microfibrils of cellulose
• amorphous component -- a matrix of alginates & fucoidan

• plasmodesmata

Order: Ectocarpales -- e.g., Ectocarpus

Characteristics

filamentous thallus

diplohaplontic life cycle

isomorphic generations

isogamous reproduction

Life cycle

on sporophyte:

plurilocular sporangia -- mitosis makes diploid spores

unilocular sporangia -- meiosis makes haploid spores

on gametophyte:

plurilocular gametangia -- mitosis makes haploid gametes

pheromones

Order: Laminariales (kelps) -- e.g., Laminaria

Characteristics

parenchymatous thallus

diplohaplontic life cycle

heteromorphic generations

oogamous reproduction

Thallus

holdfast, stipe, (meristem,) blade, gas bladders (= pneumatocysts)

meristoderm, cortex, medulla (w/ sieve cells)

Life cycle -- tiny gametophyte, sporophyte dominant

Ecology -- kelp forests

Economic importance

food

alginates

Order: Fucales -- e.g., Fucus

Characteristics

parenchymatous thallus

diplontic life cycle

oogamous reproduction

Thallus -- apical meristem

Ecology -- intertidal zone

 

Vocabulary

click here to go to Phaeophyta vocabulary