Xanthophyta PPT BY :- Dr.Pinky Diwedi

1. Xanthophyta
M.Sc.Isem.,paper-102,unit-II
Dr. Pinky Dwivedi

2. • 1.Most of the spp. are fresh water.
• 2.Plants are yellow green in colour.
• 3.Pigments are Chl.a,Chl.c & beta carotene.
Lutein & fucoxanthin are absent.
• 5.Carotenoids are excess over chlorophyll
pigments.
• 6.Chromatophores are discoid and many in each
cell.
• 7.Cell wall usually absent if present more of
pectin .
• 8.Pyrenoids are absent, reserved food material is
• fats , oil & leucosin or chrysolaminarin (glucose
polymer).

3. 9. Motile structures contain more than one chromoplast,
two unequal flagella at anterior
end,larger flagella is tinsel & shorter is whiplash type.
10. Sexual reproduction is rare if present isogamous,
Vaucheria it is oogamous.
11. Plant body is unicellular or multicellular.
12. Morhological diversity – motile
coccoid,palmelloid,filamentous and siphonous forms.
structural diversity parallels green alga but not
reached that elaboration parenchymatous and
heterotrichous forms absent.

4. It has one class- Xanthophyceae having 6
orders
Heterochloridales- motile forms
Heterococcales- coccoid forms
Hetero trichales-Tribonematales-filamentous
Heterosiphonales- siphoneous forms.
Heterocapsales- palmelloid forms.
Rhizochloridales- amoebiod forms.

5. Thallus organisation:
- unicellular-flagellated or amoebiod-
Heterochloris
-palmelloid forms – Gleochloris – vegetative
cellsin gelatinous matrix cells are in colonies.
-unicellular/multicellular nonfilamentous
vegetative cells- Mischococcus-dichotomously
branched gelatinous tubes
-branched or unbranched filamentous-
Tribonema
coenocytic in Botrydium, Vaucheria

6. Reproduction – vegetative- fragmentation.
In Botrydium vegetative reproduction is absent.
In Vaucheria it is by fragmentation.
Asexual – zoospores, aplanospores, resting spores, akinetes.
Zoospores- when plants are submerged in water.
In Botrydium a vesicle is formed its protoplast divides into
many biflagellated zoospores.
In Vaucheria –at the end of the side branch zoosporangium is
formed with a single large multinucleate and multi flagellated
zoospore- synzoospore.
Aplanospores – formed in terrestrial or wet soil. They are non
motile.
Under adverse conditions- hypnospores are formed.
akinetes in chains.
.

7. Sexual – rarely present
recorded only in Botrydium, Tribonema –
isogamous in homothallic spp(monoecious).
in heterothallic spp.-anisogamous.
Vaucheria- oogamous.
zygote-after a period of rest
In Botrychium- meiosis-4-8 biflagellated
meiospores each forms new haploid plant.
In Vaucheria-meiosis –haploid filament is
formed which develops into a new plant.