GLOEOTRICHIA

CLASSIFICATION OF GLOEOTRICHIA

Sub-division :- Algae

Class :- Myxophyceae

Order :- Nostocales

Family :- Rivulariaceae

Genus :- Gloeotrichia

Gloeotrichia occurs as mucilaginous balls or mass floating on the surface of the stagnant waters. Colonies are also found as epiphytes on aquatic weeds growing near the margins of ponds and pools

EXTERNAL FEATURES OF THALLUS AND HETEROCYST​ OF GLOEOTRICHIA

• The thallus is colonial. It is surrounded by a large mucilage. The shape appears to be spherical or hemispherical. The old colony becomes inflated and hollow.
• The colour of the colony ranges from dull brown to blackish green and is seldom blue green. The filaments in a colony are loosely arranged in radial fashion. These are more or less parallel with false branches.
• Colourless sheath is present at the base where it is firm and gradually gelatinizes outwards.
• Trichomes may be unbranched or more or less false branched. These are broad at the base and gradually taper into a hair toward the apex.
• The trichomes show a typical and distinct trichothallic growth.
• A single spherical heterocyst with a single polar granule is present at the base of the trichome.
• Each cell shows a typical cyanophycean structure. The central region does not have a nucleus, the genetic material in the form of DNA being dispersed. The pigments occur scattered in the peripheral region. A few cyanophycean granules-the major reserve food material are also present in this region

THE HORMOGONIA AND THE SPORES​ OF GLOEOTRICHIA

• Reproduction takes place by hormogones and spores or akinetes.
• Sexual reproduction is not known.
• Hormogone formation is common. These occur either singly or in series.
• Spores are also of common occurrence. These occur at the base of the trichome, generally singly, sometimes more.
• Each spore is long, cylindrical, smooth or ornamented and thick walled. 6. It is rich in reserve food material in the form of cyanophycean granules.
• Akinetes are the major organs of perennation.

IDENTIFICATION OF GLOEOTRICHIA​

• Sub-division – Algae
  1. Thallus simple,
  2. Chlorophyll present.
  3. Cell walls of cellulose.
• Class – Myxophyceae
  1. Chromatophore not organised, pigments diffused, blue-green.
  2. Photosynthetic reserve cyanophycean starch.
  3. True nucleus absent.
  4. Sexual reproduction absent.
• Order – Nostocales
  1. Thallus with trichomes, unbranched, or with false branching.
  2. Hormogones, heterocysts, exospores and endospores generally present.
• Family – Rivulariaceae
  1. Trichomes markedly attenuated from base to apex, or from middle to both extremities.
  2. Growth trichothallic, terminal hair.
  3. Trichomescommonly false branched.
• Genus– Gloeotrichia
  1. Spores large, formed singly.
  2. Filaments in spherical thallus.