Kingdom Plantae: Producers and Classification

Kingdom Plantae

• Classified into two sub-kingdoms: Cryptogamae (spore-producing plants) and Phanerogamae (seed-producing plants)

Sub-kingdom Cryptogamae

• Divided into three divisions: Thallophyta, Bryophyta, and Pteridophyta
• Thallophyta (algal division):
  • Examples: Chlorella, Chlamydomonas, Spirogyra, Chara, and Sargassum
  • Characteristics: unicellular or multicellular, aquatic, and thalloid (undifferentiated plant body)
• Bryophyta (mosses):
  • Examples: Riccia, Marchantia, and Funaria
  • Characteristics: terrestrial, thalloid or leafy, and amphibious (need water for fertilization and completion of life cycle)
  • Divided into two groups: liverworts and mosses
• Pteridophyta (fern-like plants):
  • Examples: Ferns, Horsetail, and Lycopodium
  • Characteristics: vascular, heteromorphic alternation of generations, and terrestrial
  • Divided into four classes: Psilopsida, Lycopsida, Sphenopsida, and Pteropsida

Sub-kingdom Phanerogamae

• Divided into two classes: Gymnospermae and Angiospermae

• Gymnospermae:

  • Examples: Cycas, Pinus, and Ginkgo biloba
  • Characteristics: vascular, naked seeds, and evergreen shrubs or trees
  • Plant body is sporophyte, with Xylem and Phloem
  • Stem is erect, solid, and cylindrical, with secondary growth
  • Leaves are dimorphic (foliage leaves and scale leaves)

• Angiospermae:

  • Examples: Hibiscus, Peepal, Canna, and Tulsi
  • Characteristics: vascular, seeds enclosed within the fruit, and heteromorphic alternation of generations
  • Divided into two classes: Monocotyledonae and Dicotyledonae
  • Monocotyledonae:
    • Characteristics: single cotyledon in embryo, adventitious root system, and rarely branched stem
  • Dicotyledonae:
    • Characteristics: two cotyledons in embryo, tap root system, and branched stem### Angiosperms

• Angiosperms are flowering plants with seeds formed in megasporangia (or ovules) borne on highly specialized megasporophylls called carpels.

• They have conjoint, collateral, and closed vascular bundles in their stems.

• Flowers are generally trimerous, with essential whorls of microsporophylls (Androecium) and megasporophylls (Gynoecium), and accessory whorls of calyx (sepals) and corolla (petals).

• Angiosperms are subdivided into two classes: Dicotyledonae (Dicots) and Monocotyledonae (Monocots).

Dicotyledonae (Dicots)

• Characterized by two cotyledons in their embryo.
• Tap root system and branched stem.
• Leaves show reticulate venation and flowers have tetra- or pentamerous symmetry.
• Vascular bundles are conjoint, collateral, and open, with cambium present for secondary growth.
• Examples: Helianthus annuus (sunflower), Hibiscus rosa-sinensis (China rose).

Monocotyledonae (Monocots)

• Characterized by one cotyledon in their embryo.
• Fibrous root system and unbranched stem.
• Leaves show parallel venation and flowers have trimerous symmetry.
• Vascular bundles are conjoint, collateral, and closed, with no cambium for secondary growth.
• Examples: Zea mays (maize), Sorghum vulgare (jowar).

Gymnosperms and Angiosperms

• Gymnosperms and Angiosperms differ in that Angiosperms have enclosed seeds, whereas Gymnosperms have naked seeds.
• Angiosperms have a more complex reproductive structure with carpels and stamens, whereas Gymnosperms have simpler reproductive structures with cones.

Plant Life Cycle and Alternation of Generations

• A plant's life cycle includes two phases: sporophyte (diploid) and gametophyte (haploid).
• The sporophytic and gametophytic generations alternate in the life cycle of a plant.
• In Bryophytes and Pteridophytes, the gametophyte is dominant, whereas in Gymnosperms and Angiosperms, the sporophyte is dominant.
• The life cycle can be haplontic, diplontic, or haplo-diplontic, depending on the dominant phase.

Life Cycle Types

• Haplontic: Haploid multicellular organism, mitosis occurs in haploid cells, and zygote is formed after fertilization.
• Diplontic: Diploid multicellular organism, mitosis occurs in diploid cells, and gametes are formed through meiosis.
• Haplo-diplontic: Both haploid and diploid multicellular organisms, mitosis occurs in both haploid and diploid cells.

Test your knowledge about Kingdom Plantae, including why plants are called producers and the differences between sub-kingdoms Cryptogamae and Phanerogamae.