2. Floral Diversity

2. Floral Diversity (30 Hours)

2.1 Introduction

• Three Domains of Life:
  • Bacteria: Prokaryotic, unicellular organisms with a simple cell structure.
  • Archaea: Prokaryotic organisms similar to bacteria but with distinct biochemistry and genetics, often found in extreme environments.
  • Eukarya: Organisms with complex cells containing membrane-bound organelles, including plants, animals, fungi, and protists.
• Binomial Nomenclature:
  • A standardized naming system developed by Carl Linnaeus, where each species is given a two-part name: genus and species (e.g., Homo sapiens).
• Five Kingdom Classification System:
  • Monera: Unicellular organisms, primarily bacteria and cyanobacteria.
  • Protista: Diverse group including unicellular and simple multicellular organisms (e.g., protozoa and algae).
  • Fungi: Eukaryotic organisms that obtain nutrients through absorption, characterized by chitin in their cell walls.
  • Plantae: Multicellular organisms capable of photosynthesis, characterized by cell walls made of cellulose.
  • Animalia: Multicellular, heterotrophic organisms that lack cell walls.
• Status of Flora in Nepal:
  • Overview of the diversity of plant species in Nepal, including endemic species and conservation efforts.
• World Representation: Discussion on global flora, including biodiversity hotspots and conservation issues.

2.2 Fungi

• General Introduction:
  • Fungi are a separate kingdom of eukaryotic organisms that play vital roles in ecosystems as decomposers.
• Characteristic Features:
  • Eukaryotic, heterotrophic, with a cell wall made of chitin; reproduce through spores.
• Major Groups:
  • Phycomycetes: Aquatic and terrestrial fungi, characterized by non-septate hyphae (e.g., Mucor).
  • Ascomycetes: Known as sac fungi, reproduce sexually through ascospores (e.g., yeast).
  • Basidiomycetes: Club fungi, produce basidiospores (e.g., mushrooms).
  • Deuteromycetes: Imperfect fungi, primarily reproduce asexually (e.g., penicillin-producing molds).
• Structure and Reproduction:
  • Mucor: A common mold with a coenocytic structure, reproducing through both asexual and sexual spores.
  • Yeast: Unicellular fungi primarily reproducing asexually by budding.
• Mushrooms:
  • Poisonous and Non-Poisonous Mushrooms: Discussion on identification and significance of various types.
• Economic Importance:
  • Role in food production (e.g., bread, beer), medicine (e.g., antibiotics), and environmental sustainability (e.g., decomposers).

2.3 Lichen

• General Introduction:
  • Lichens are symbiotic associations between fungi and photosynthetic organisms (e.g., algae or cyanobacteria).
• Characteristic Features:
  • Resilient organisms found in various habitats; can survive extreme conditions.
  • Often used as bioindicators of environmental health.
• Economic Importance:
  • Sources of dyes, perfumes, and medicinal compounds; play a role in soil formation.

2.4 Algae

• General Introduction:
  • Simple, photosynthetic organisms that can be unicellular or multicellular; important primary producers in aquatic ecosystems.
• Characteristic Features:
  • Contain chlorophyll and other pigments; vary in size and shape.
• Major Groups:
  • Green Algae: Contain chlorophyll a and b; examples include Chlorella and Spirogyra.
  • Brown Algae: Include larger forms like kelp; important for marine ecosystems.
  • Red Algae: Found in deeper waters, contain phycoerythrin; examples include Porphyra.
• Structure and Reproduction:
  • Spirogyra: Filamentous green algae with spiral chloroplasts; reproduces sexually through conjugation and asexually via fragmentation.
• Economic Importance:
  • Used in food (e.g., seaweeds), fertilizers, and as a source of biofuels.

2.5 Bryophyta

General Introduction

• Definition: Bryophytes are non-vascular land plants, often referred to as "mosses, liverworts, and hornworts." They are key players in terrestrial ecosystems and are known for their ability to colonize land.
• Habitat: Typically found in moist environments, they can also inhabit drier areas where they are often resilient to desiccation.

Characteristic Features

• Liverworts:
  • Flat, leaf-like structures; some have thalloid forms.
  • Lack true roots, stems, and leaves but may have structures resembling them.
• Hornworts:
  • Recognizable by their elongated sporophyte that resembles a horn.
  • Contain chloroplasts in their sporophyte, allowing them to perform photosynthesis.
• Mosses:
  • Have leafy stems and a distinct structure with a gametophyte dominant life cycle.
  • Form dense mats in moist environments.

Morphological Structure and Reproduction of Marchantia

• Structure:
  • Thallus: Flattened and lobed structure; the main body of the plant.
  • Rhizoids: Hair-like structures anchoring the thallus to the substrate.
  • Gemmae Cups: Structures for asexual reproduction.
• Reproduction:
  • Asexual Reproduction: Through gemmae cups.
  • Sexual Reproduction: Involves antheridia (male) and archegonia (female) for gamete production, leading to fertilization and sporophyte development.

Economic Importance

• Serve as indicators of environmental health.
• Used in soil conservation and as components in gardening (e.g., peat moss).
• Some have medicinal uses.

2.6 Pteridophyta

General Introduction

• Definition: Pteridophytes, commonly known as ferns, are vascular plants that reproduce via spores.
• Habitat: Found in diverse environments, from tropical forests to temperate regions.

Characteristic Features

• Possess vascular tissues (xylem and phloem).
• Do not produce seeds; reproduce through spores produced in sporangia on the underside of leaves (fronds).
• Have a dominant sporophyte generation.

Morphological Structure and Reproduction of Dryopteris

• Structure:
  • Fronds: Large, divided leaves that are characteristic of ferns.
  • Rhizome: Horizontal underground stem from which fronds arise.
• Reproduction:
  • Sporangia: Located on the underside of fronds in clusters called sori.
  • Spores are released and germinate into gametophytes, leading to the production of gametes.

Economic Importance

• Used as ornamental plants in landscaping.
• Some ferns are edible (e.g., fiddleheads).
• Serve ecological roles in stabilizing soil and providing habitat.

2.7 Gymnosperm

General Introduction

• Definition: Gymnosperms are seed-producing plants that do not form flowers or fruits; their seeds are exposed on cones.
• Habitat: Mainly found in temperate and boreal regions.

Characteristic Features

• Produce seeds that are often exposed on cone scales.
• Have needle-like leaves adapted to conserve water in harsh conditions.

Morphology and Reproduction of Pinus

• Structure:
  • Needles: Long, slender leaves that reduce water loss.
  • Cones: Male cones produce pollen; female cones contain ovules that develop into seeds.
• Reproduction:
  • Pollination: Occurs via wind; pollen grains reach female cones.
  • Fertilization: After pollination, seeds develop within the female cone.

Economic Importance

• Source of timber, paper, and resin.
• Used in landscaping and reforestation efforts.

2.8 Angiosperm

Morphology

• Root: Anchors the plant and absorbs water and nutrients.
• Stem: Supports the plant and transports nutrients and water.
• Leaves: Primary sites for photosynthesis.
• Inflorescences and Flowers: Structures for reproduction, often attracting pollinators.
• Fruit: Develops from fertilized ovary and aids in seed dispersal.

Taxonomic Study

• Definition: The science of naming and classifying living organisms.
• Taxonomic Hierarchy: Domain > Kingdom > Phylum > Class > Order > Family > Genus > Species.
• Classification Systems:
  • Artificial Classification: Based on arbitrary criteria (e.g., flower color).
  • Natural Classification: Based on evolutionary relationships.
  • Phylogenetic Classification: Reflects evolutionary history and genetic relationships.

Taxonomic Description of Families

• Brassicaceae (Mustard family):
  • Known for cruciferous vegetables (e.g., cabbage, broccoli).
• Fabaceae (Legume family):
  • Includes peas and beans; important for nitrogen fixation.
• Solanaceae (Nightshade family):
  • Contains economically important plants like potatoes and tomatoes.
• Liliaceae (Lily family):
  • Includes ornamental plants and some edible species (e.g., onions, garlic).

Economic Importance

• Angiosperms provide food, medicine, textiles, and ornamental plants, playing a vital role in human life and ecosystems.