PRELIMS

Botany: Phanerogams and Plant Families

Phanerogams are well-developed flowering plants that produce seeds. They are divided into Gymnosperms and Angiosperms.

I. Gymnosperms (Naked Seeds)

Woody, perennial, and often tall trees/bushes.

• Longest Plant: Sequoia gigantea (Redwood of California); can reach 120 meters.
• Smallest Plant: Zamia pygmaea.
• Living Fossils: Cycas, Ginkgo biloba (Maidenhair tree), Metasequoia.
• Economic Importance:
  • Food: Sago is extracted from the stem of Cycas (Sago-palm).
  • Timber: Pine, Deodar, Spruce used for furniture.
  • Oils: Tarpin oil (Pine), Cedrus oil (Deodar), Cedcast oil (Juniper).
  • Resin: Used for varnish, polish, and paint.

II. Angiosperms (Enclosed Seeds)

Found inside fruits. Classified based on the number of Cotyledons.

A. Monocotyledons (Single Cotyledon)

• Liliaceae: Garlic, Onion.
• Palmae: Coconut, Palm, Date, Nut.
• Gramineae: Wheat, Rice, Maize, Sugarcane, Bamboo, Bajra, Oat.

B. Dicotyledons (Two Cotyledons)

• Cruciferae: Radish, Turnip, Mustard.
• Malvaceae: Jute, Lady's finger (Okra).
• Leguminosae: Pulses, Tamarind, Babool, Ashok.
• Solanaceae: Potato, Tomato, Brinjal, Chilly, Tobacco.
• Rutaceae: Lemon, Orange, Citrus fruits.
• Cucurbitaceae: Melon, Watermelon, Gourd, Bitter gourd.
• Compositae: Sunflower, Marigold.
• Rosaceae: Apple, Strawberry, Almond.

Confused Pair: Monocot vs Dicot

Monocotyledons

• Cotyledons: One
• Root: Fibrous root system
• Leaf Venation: Parallel
• Floral Parts: Multiples of 3
• Stem Vascular Bundles: Scattered

Dicotyledons

• Cotyledons: Two
• Root: Tap root system
• Leaf Venation: Reticulate (net-like)
• Floral Parts: Multiples of 4 or 5
• Stem Vascular Bundles: Arranged in a ring

UPSC Relevance

Plant families and their economic uses are direct links to Geography and Agriculture.

• Monocot/Dicot: Identifying major crops like Wheat/Rice as Gramineae (Monocot) versus Pulses as Leguminosae (Dicot).
• Gymnosperms: The biological uniqueness of "Living Fossils" and the industrial use of Coniferous resins/oils.
• Horticulture: Categorizing fruits like Apple/Strawberry into the Rosaceae family.