11th Class

In higher forms the mycelium gets organised into loosely or compactly woven structure which looks like a tissue called plectenchyma. It is of two types : Prosenchyma : It comprises loosely woven hyphae lying almost parallel to each other. Pseudoparenchyma : If the hyphae are closely interwoven, looking like parenchyma in a cross-section, it is called as pseudoparenchyma. In addition to above, the fungal mycelium may form some specialized structures as under : Rhizomorphs : It is a 'root or string-like' elongated structure of closely packed and interwoven hyphae. The rhizomorphs may have a compact growing point. Sclerotia : Here the hyphae gets interwoven forming pseudoparenchyma with external hyphae becoming thickened to save the inner ones from desiccation. They persist for several years. Stroma : It is thick mattress of compact hyphae associated with the fruiting bodies.

The plant body of true fungi (Eumycota) is thallus. It may be non-mycelial or mycelial. The non-mycelial forms are unicellular, however, they may form a pseudomycelium by budding. In mycelial forms, the plant body is made up of thread like structures called hyphae (sing. hypha). The mycelium may be aseptate (non-septate) or septate. When non-septate and multinucleate, the mycelium is described as coenocytic. In lower fungi the mycelium is non-septate e.g., Phycomycetes. In higher forms it is septate e.g., Ascomycetes, Basidiomycetes and Deuteromycetes. In some forms the plant body is unicelled at one stage and mycelial at the other. Their organization is sometimes described as dimorphic. When the entire mycelium is converted into reproductive structure, the thallus is described as holocarpic. However, if only a part of it becomes reproductive, the thallus is called as eucarpic.

(Gk. Phycos = alga or sea weed) The branch of botany dealing with the study of algae is called as phycology or algology. They are simple, thallose, autotrophic non-vascular plants having unicelled sex organs and no embryo formation. In Whittaker's classification, algae are grouped in three kingdom – Monera (blue green algae), Protista (dinoflagellates, diatoms, euglenoids) and Plantae (green algae, red algae and brown algae). According to Fritsch, (1935) the designation alga must include all holophytic organisms, as well as their numerous colourless derivatives, that fail to reach the level of differentiation characteristic of archegoniatae plants. Occurrence : The algae occur in a variety of habitats which are summarised here under : Fresh water forms : They occurs in rivers, ponds, pools, lakes and ditches. Those forms which remain attached to bottom soil are called as epipelic. Several forms remain attached to bottom or at the bank or to submerged more...

(Gk. Bryon = moss; phyton = plants) Bryophyta includes the simplest and primitive land plants. Which are characterised by the persence of independent gametophyte and parasitic sporophyte. The term bryophyta was coined by Braun (1864) but bryophytes were delimited in its present form by Schimper (1879). It occupies a position intermediate between algae and pteridophyta. Due to peculiar type of their habitats, they are regarded as 'the amphibians of the plant kingdom'. The science connected with the study of bryophytes called bryology. Habitats Bryophytes usually grow in moist and shady places. The plants grow densely together and form green carpets or mats on damp soil, rock, walls, barks of trees and on decaying logs in forests, especially during the rainy season. Specialized habitats : Some bryophytes grow in diverse habitats such as – aquatic (e.g., Riccia fluitans, Ricciocarpus natans, Riella), epiphytes (e.g., Dendroceros, Radula protensa and many mosses), saprophytes (e.g., more...

(Gk. Pteron = father/fern; phyton = plants) The term pteridophyta was first introduced by Haeckel in (1866). The pteridophytes are flowerless, seedless, spore producing vascular plant which have successfully invaded the land. Pteridophytes represent an intermediate position between bryophytes and spermatophytes (Gymnosperm and Angiosperm). They are also called vascular cryptogams. (The term cryptogams was coined by Linnaeus (1737) which means plants without seeds). The group has a long fossil history. Pteridophytes flourished well during devonian, mississipian and pensylvanian periods of late paleozoic age. This period can be well recognised as "age of pteridophyta". Habitat The plants of pteridophytes are mostly terrestrial. They prefer shady habitats. Some species of Selaginella and Adiantum are xerophytes. A fern, Acrostichum aureum is a halophyte. Some species e.g., Selaginella oregana, Psilotum flacidum, Lycopodium squarrosum and ferns like Asplenium nidus, Pleopeltis sp. are epiphytes. Marsilea occurs as a terrestrial, amphibious as well as an aquatic plant. more...

Habitat It is an unbranched filamentous green alga of stagnant fresh waters which forms floating masses (supported by bubbles of oxygen) called pond scum. A sheath of muscilage occurs on the outside. It gives a silky touch. Hence Spirogyra is also called water silk or mermaid's tresses. Structure The thallus is an unbranched and uniseriate filament where cells are arranged in a single row. In some species hold fast is present (e.g., S. fluviatilis). The cells are elongated and cylindrical. The cell wall is two layered the outer is of pectic substance and the inner of cellulose. The outer part (pectin) dissolves in water to form a muscilaginous sheath. Due to this reason Spirogyra filament's are slippery. Transverse or septum can be plane, colligate (with H-shaped piece), replicate (ring like ingrowths) and unduliseptate (undulate). The protoplast more...

Habitat Funaria is known as common moss or green moss or cord moss. There are 117 species of Funaria which are worldwide or cosmopolitan in distribution. 25 species have been reported from India. Most common species are Funaria hygrometrica, F.obtusa, F. attentua and F. fasicularis. Funaria grows well in recently burnt grounds rich in plant ashes (alkaline condition). Common places for its growth are moist rocks, moist walls and moist grounds. External structure (Gametophytic phase) : The main plant body of Funaria is gametophyte and is of two forms. (1) Juvenile form (creeping protonema). (2) Adult form  (leafy gametophore). Protonema is the branched filamentous portion which is produced by germination of spores. It is ephemeral or short lived. Leafy gametophore develop from buds produced on protonema and is made up of axis with spirally arranged leaves. more...

(Gk. Angeion = covered; sperma = seed) Introduction The angiosperms, or flowering plants, constitute the most dominant and ubiquitous vascular plants of present day flora which changed the green and yellow melancholy of the earth's vegetation by the colourful brightness and fragrance of their flower. The term angiosperm means 'enclosed seed' because the ovules or potential seeds are enclosed within a hollow ovary. In this respect they are considered most highly evolved and advanced as compared with the naked seeded gymnosperms. Characteristic features (1) Angiospermous plants grow in almost every kind of habitats. In the deserts, these plants grow, flower, shed seeds and complete their life cycle in a few weeks of rainy season. Some flowering plants like Zostera, occur in shallow seas. A small orchid even lives underground. It survives as a saprophyte on decaying organic matter because of the mycorrhizal association which helps to obtain nourishment. In rain more...

(Gk. Gymnos = naked; sperma = seed) The term gymnosperm was introduced by Theophrastus. Gymnosperm (Gk. Gymnos = naked ; sperma = seed) are the plants with exposed or naked seeds or ovules. These plants represent the most ancient group of seed plants. Gymnosperms are called fruitless phanerogames or flowering plants without ovary Robert Brown (1827) separated them from angiosperms and placed under a distinct group due to presence of unprotected ovules in them. The gymnosperms originated much earlier then angiosperms. However, most of the members of this group have now become extinct and only few living forms are known today. Distribution Plants of gymnosperms occur throughout the world. The group is presently represented by only 900 living species. Of these, about 500 species belong to 'Conifers' or cone bearing plants. Several species of conifer occur in north-west America and eastern and central China. In India several members are found more...

Habitat It is commonly known as pine with about 90 species among which six species are found in India. (N. East and N. West Himalayas) occurring in wild state. These are Pinus gerardiana (Chilgoza pine), P. Wallichiana (Blue pine or Kail), P.roxburghii (Chir pine), P.merkusii (Teenasserim pine), P.insularis (Khasi pine), and P.armandi (Armand's pine). In addition to these, 4 sps. of exotic pines, i.e., P.montana, P.laricia and P.sylvestris (Scotch pine) and P.strobus (white pine) have been introduced in India. P.excelsa are found at maximum height i.e., grow upto 3500 m above see level. Structure External structure : Pinus is an evergreen, perennial plant of xerophytic nature. Mostly the species are tall and straight. The whorled branching gives a typical conical or excurrent appearance to the plant (due to apical dominance). The plant body is sporophyte and more...