The algae comprise of a large heterogeneous assemblage of plants which are diverse in habitat, size, organisation, physiology, biochemistry, and reproduction. The algae are ubiquitous (present every¬where) in distribution, i.e., they are found in fresh water as well as marine water, on soil, on rock, as epiphytes or parasites on plants and animals, in hot springs, in desert, on permanent snow-fields etc. But they mainly dwell in aquatic environments

1. ALGAE
Dr. Shital V. Surve
Assistant Professor
Department of Botany
G s gawande mahavidyalay,
umarkhed dist yavatmal (m.s.)

2.  INTRODUCTION
 Term first introduced by Linnaeus (1753)
 Important group of Thallophyta (Thallos - a sprout; phyton - a plant).
 Systematic study of algae - Phycology
 The primitive and simplest division of the plant kingdom.

3.  DEFINATIONS
1. Fritsch, F. (1935) - The holophytic organisms (as well
as their numerous colourless derivatives) that fail to
reach the higher level of differentiation characteristic of
the higher plants.
2. Smith, G. M. (1955) - Simple plants with an
autotrophic mode of nutrition.
3. Chapman, V. J. (1962) - (seaweeds of the seashore
and green skeins in stagnant fresh water, ponds and
pools) as among the simplest in the plant kingdom.

4. 4. Prescott, G. W. (1969) - Chlorophyll-bearing organisms
(and their colourless relatives) which are thalloid.
5. Singh, R. N. (1974) - Large simple plants which display
a spectrum of photosynthetic pigments and evolve
oxygen during the process of photosynthesis.
6. Sharma (1987) – Chlorophyll bearing autotropic
thallophytes bounded by a cell wall made up of pure or
mixed carbohydrates.

5.  CHARACTERISTICS OF ALGAE:
 Algae are chlorophyll-bearing autotrophic thalloid plant body.
 Almost all are aquatic.
 Unicellular to multicellular structure.
 Lack vascular tissue.
 Sex organs are generally unicellular but, when multicellular,
all cells are fertile and the entire structure does not have any
protection jacket.
 Zygote undergoes development by mitosis or meiosis, no
embryo formation.
 Plants having distinct alternation of generations.
 Both gametophyte and sporophyte generations — when
present in the life cycle are independent.

6.  GENERAL CHARACTERS WITH
REFERENCE TO HABITAT
1. Aquatic algae.
2. Terrestrial algae.
3. Aerophytes
4. Cryophytes
5. Thermophytes
6. Algae of unusual habitats.

7.  Completely submerged or free floating.
 Fresh water (ponds, lakes, tanks, ditches, streams or in
slow running rivers) or Marine (sea, salinity is 33-40%)
 Fresh water algae Chlamydomonas, Volvox, Ulothrix,
Chara, Oedogonium, Spirogyra, Nostoc, Oscillatoria
 Marine algae are Sargassum, Laminaria, Ectocarpus,
Polysiphonia, Caulerpa, Bangia, Padina etc
1. AQUATIC ALGAE

8.  Fresh Water Algae

9.  Marine Algae

10. 2.TERRESTRIAL ALGAE
 Grow in terrestrial habitats like soils, rocks, logs etc.
 Grow on the surface of the soil are known as saprophytes.
 Grow under the surface of the soil (subterranean), and are called
cryptophytes.
 Vaucheria geminata, Fritschiella sp., Oscillatoria sancta, Chlorella
lichina, Euglena sp., and Phormidium sp.

11.  Saprophytes
 Cryptophytes

12. 3. AEROPHYTES
 Algal form adapted for aerial mode of life
 Occur on tree trunks, moist walls, flower pots, rocks
Scytonema Trentepohlia

13. 4. CRYOPYTES
 Group of algae growing on ice or snow
 Found on mountain peaks and impart attractive colors to it.
Hematococcus Ancyclonema

14. 5. THERMOPHYTES
 Occurs in hot water springs (50- 80°C)
 Many blue-greens (e.g., Synechococcus elongates,
Heterohormogonium sp.)
 Oscillatoria brevis

15.  ALGAE OF UNUSUAL HABITATS
1. Halophytic Algae (or Eurhaline):
 Grow in saline water the highly concentrated salt.
Ex - Chlamydomonas ehrenbergli, Dunaliella and Stephanoptera sp.
2. Lithophytic Algae:
 Grow on the moist surface of stones and rocks.
Ex - Nostoc, Gloeocapsa, Rivularia.
3. Epiphytic Algae:
 Algae grow on other aquatic plant.
Ex - Oedogonium, Chaeotophora.

16. 4. Epizoic Algae :
 Algae grow on shell of molluscs, turtles and fins of fishes.
Ex - Cladophora, Protoderma.
5. Endozoic Algae
 Algae found inside the body of aquatic animals.
Ex - Zoochorella, Zooxanthella.
6. Parasitic Algae
 Some algae grow parasitically on different plants and animals.
Ex - Cephaleuros, Chlorochytrium.

17. 7. Symbiotic Algae:
 They grow in association with fungi, bryophytes, gymnosperms or
angiosperms.
 Association with fungi - Nostoc, Gloeocapsa, Rivularia.
 Association of algae and fungi – Lichen,
 Nostoc with Anthoceros, Anabaena with Cycas roots (coralloid roots)
8. Psammon:
 The algae which grow in sandy beaches are called psammon,
Ex - Vaucheria, Phormidium etc.