Bryophytes

BRYOPHYTES

Classification of Bryophytes into 3 phyla:                                                               

i) Phylum Bryophyta (Polytrichum sp.)                                           

ii) Phylum Hepatophyta (Marchantia sp.)                                       

iii) Phylum Anthocerophyta (Anthocerous sp.)                             

UNIQUE CHARACTERISTICS

• Most primitive terrestrial plants 
• Habitat : damp, shady places (highland area) 
• Non-vascular plants
• No true stems, leaves & root 
• Have rhizoids (attach to the soil) 
• Gametophyte generation is dominant

• Gametes develop within gametangia. 
• Male gametangium:   antheridium produces antherozoid
• Female gametangium: archegonium produces oosphere 
• Sporophytes are smaller & shorter lived and depend on the gametophytes for the water and nutrients. 

i)Phylum Bryophyta (eg: Polytrichum sp.)

• The most familiar Bryophytes are mosses. 
• Upright gametophyte with “stem” and “leaves”
• Simple vascular tissue
• Sexual reproduction – need water
• Sporophyte (larger than liverworts) is attached to the gametophyte provides water & nutrients.

ii) Phylum Hepatophyta (eg: Marchantia sp.)

 

 

•  main plant body = thallus (flattened dark green) 
•  no true roots, stems and leaves (no vascular tissue).
•  rhizoids which anchor the thallus = absorb water and minerals. 

 

iii) Phylum Anthocerophyta (eg: Anthoceros sp.)

 

 

• Smallest group of Bryophytes
• Hornworts  tall narrow sporophytes embedded in the gametophyte tissues
• Similar to liverworts
• Presence of a single large chloroplast in each cell
• Sporophytes attached to gametophyte but sporophyte continue

 

 

   TERRESTIAL ADAPTIONS

 

Following are adaptations in Bryophytes to adapt land habitat:

 

• It has a compact multicellular plant body which helped in the conservation of water by reducing cell surface that exposed to dry land condition

 

• Modification of photosynthetic tissues for the absorption of CO2 without losing much water and exposure to light 

 

 **have flat, broad tissues that function somewhat like leaves 

 

 **very small plants, usually 1-2cm in height  

 

 **Special structures like rhizoids were developed for absorption of water and attach the plant to the soil

 

 • For sexual reproduction, Bryophytes need water. The motile sperm is dependent on water to swim to fertilize the egg.

 

 • Multicellular embryo was formed which was retained inside the female reproductive body during its development

 

 

 

 

1. Alternation of generation is clear in the life cycle of Polytrichum sp.
2. It starts from spores haploid develop into protonemata
3. The haploid protonemata grow into male and female gametophytes
4. Male and female gametophytes, with antheridia and archegonia respectively are found in different plants
5. Antheridium produces antherozoids while archegonium produces oospheres 
6. Antherozoid swims through a film of moisture to an archegonium and fertilizes the oosphere
7. The diploid zygote develops into a sporophyte
8. The sporophyte grows a long stalk or seta, that emerges from the archegonium
9. Attached by its foot, the sporophyte remains nutritionally dependent on the gametophyte
10. Meiosis occurs and haploid spores develop in the sporangium of the sporophyte
11. When sporangium lids pop, the spores released