1. Systematic Position (Classification)
Kingdom: Fungi
Division: Ascomycota
Class: Lecanoromycetes
Order: Lecanorales
Family: Parmeliaceae
Genus: Parmelia
2. General Introduction
Parmelia is a foliose lichen, commonly found growing on tree bark, rocks, and walls.
It shows a leaf-like thallus and is one of the most commonly studied lichens in botany courses.
It is a symbiotic association between:
Mycobiont: Ascomycete fungus
Phycobiont: Green alga (Trebouxia)
3. Habitat
Corticolous (on tree bark)
Saxicolous (on rocks)
Widely distributed in tropical, temperate, and subtropical regions
Grows well in clean air, sensitive to pollution
4. Thallus Structure
Type: Foliose
Colour: Grey, greenish-grey, or brown
Form: Flat, lobed, leaf-like
Attachment: Loosely attached to substratum by rhizines
External Features
Upper surface: Smooth, may bear soredia or isidia
Lower surface: Dark coloured with rhizines
Internal Structure
Upper Cortex
Compact fungal hyphae
Protective layer
Algal Layer
Green algal cells (Trebouxia)
Photosynthetic zone
Medulla
Loosely arranged fungal hyphae
Storage and gas exchange
Lower Cortex
Well developed
Gives rise to rhizines
5. Reproduction
A. Vegetative Reproduction
Fragmentation
Soredia: Powdery reproductive bodies
Isidia: Finger-like outgrowths on thallus
B. Asexual Reproduction
By conidia formed in pycnidia (rare)
C. Sexual Reproduction
Occurs through the fungal partner
Fruiting body is apothecium
Apothecium
Disc-shaped, brown to black
Usually lecanorine (thallus margin present)
Asci
Club-shaped
Produce 8 ascospores
6. Nutrition
Algal partner: Manufactures carbohydrates by photosynthesis
Fungal partner: Absorbs water, minerals and provides protection
Relationship is mutualistic
7. Economic Importance
Source of dyes
Medicinal uses (antibiotic properties)
Indicator of air pollution
Used in perfume industry (lichen acids)
8. Ecological Importance
Pioneer in soil formation
Helps in nutrient cycling
Provides shelter to small organisms
9. Diagnostic Features (Exam Points)
Foliose lichen
Rhizines present
Algal partner → Trebouxia
Reproduction by soredia & isidia
Fruiting body → apothecium
