Tag: introduction to pteridophytes

Tracheophytes are plants having dignified and developed vascular tissue for conducting water and minerals. Spermatophytes are plants that produce seeds. All tracheophytes are not spermatophytes (pteridophytes aren't spermatophytes). Phanerogams is however, an alternative them for spermatophytes.

Cryptogams are plant or plant-like orgnaisms which reproduce by spores. Examples include algae, lichens, liverworts, mosses ferns. They do not have true flowers or seeds. They include thallophyta, bryophyta and pteridophyta. In these, reproductive organs are hidden.

Vascular tissues are also known as conductive tissue, they help to conduct water and other substances from one part of the plant body to another. For example, ferns contain two types of vascular tissue, xylem and phloem, which move nutrients throughout the plant and allow them to grow tall. 

Marsilea is a water fern that produces specialized, hard, bean-shaped reproductive structures known as sporocarps. These structures contain the sporangia.

• Homosporous plants are those which produce spores of one kind only that are not differentiated by sex. The spores of homosporous plants grow into bisexual gametophytes, producing both male and female gametes.
• Lycopodium is a genus of clubmosses, belonging to the family Lycopodiaceae. It contains kidney-shaped or reniform sporangia which contain spores of one kind only (homosporous) and are borne on the upper surface of the leaf blade of specialized leaves (sporophylls).
• Equisetum is the only living genus belonging to the family Equisetaceae. They are mostly homosporous, in which spores are borne under sporangiophores.

The sporocarp is a characteristic reproductive structure found in the genus Marsilea, which is a heterosporous aquatic fern.

• A thallus is composed of filaments or plates of cells and ranges in size from a unicellular structure to a complex tree-like form.
  
• Thallophyta is a division of the plant kingdom including primitive forms of plant life showing a simple plant body i.e thallus like plant body. For example, unicellular to large algae, fungi, lichens.
• The Thallophyta have been divided into two subdivisions. They are  Myxothallophyta (myxomycetes) and Euthallophyta (bacteria, fungi, lichens, algae).
• Hence Plants having thallus bodies are known as 'Thallophyta'.