COMMENTS ON FUCUS
Habit
Marine algae:- Fucus is a cold water marine algae found attached to rocks in Sea by a narrow holdfast.
Vegetative Structure
Thalloid body:
The plant is dichotomously branched thalloid consisting of holdfast, stipe and frond or laminia.
Air bladders:
The frond bean spherical swollen vesicles-like air bladders embedded within the ribbon-like branches. These bladders give buoyancy to the plant.
Crypto Blasts:
There are many small dot-like bodies all over the frond. They are flasks, like sterile conceptacles called Crypto Blasts. They open outside in a cryptostomata containing numerous paraphyses.
Receptacle:
The fertile reproductive branches bear a number of Swollen conical receptacles at their tips. This reproductive region is occupied with minute wart-like projections known as conceptacles embedded in the superficial part of medullary Zone.
Internal Structure Of Thallus
i) Epidermis:
The frond is externally bounded by a thin walled palisode-like layer containing numerous chromatophores. The wall on the upper layer of thallus is called upper epidermis and on the lower layer of thallus as lower epidermis. Both the layers are externally ensheathed by thick cuticles like hard layers.
ii) Cortex:
Below the upper and lower epidermal layers lie a few layers of compactly arranged parenchymatous tissue known as outer epidermal cortex for the upper one and inner epidermal cortex for the lower portion.
iii) Medullo:
The central region between the upper and lower cortex is occupied by central elongated loosely interwoven incompletely septate filaments called medulla.
Sexual Reproductive Structure
The reproduction is oogamous types:
i) Antheridium:
It is a small stalked, spherical body borne on the tip of much branch paraphysis near the base and side of Conceptacle. It is enclosed by antherozoids of sperms. The antherozoids are one pyriform, uninucleated with two flagella inserted laterally. The anterior flagellum is shorter than the posterior one.
ii) Oogonium:
It is a small stalked three layered globose or oval organ. The outer wall is termed as exochuite, middle one Masochuite and inner on endochuite. It is borne directly from the conceptacle and remains intermingled with the unbranded uniseriate hair, like paraphyses. Each oogonium contains uninucleate non-motile, rounded eggs or cospheres.
