BIS 2C Lecture Notes - Lecture 15: Marchantiophyta, Sporophyte, Gametophyte
27 Apr 2018
School
Department
Course
Adaptations of First Plants on Land (Embryophytes)
Appeared on land 400-500 mya
•
Difficulties: drying out/losing water, spreading spores, performing gas exchange for CO2
•
Adaptations
Cuticle - waxy coating to prevent water loss
○
Stomata - regulates gas exchange
○
Gametangia: organs with gametes (vessel = angia-)
○
Embryophytes (land plants) have protection on embryos
○
Pigments that protect against UV
○
Thick spore walls that prevent desiccation
○
Mutualisms with fungi that promote nutrient uptake (mycorrhizae) u
○
•
Nonvascular Land Plants (Bryophytes)
Not a monophyletic group; includes liverworts, mosses and hornworts
•
Most similar to earliest land plants
•
Characteristics
No vascular transport system so can't grow tall and have no rigidity to support large growth
○
Must live in moist habitat because have a thin cuticle anyways
○
Lack true leaves and stems and roots but sometimes have analogous structures
○
Water transport through diffusion and capillary actions, very slow so can't grow too large
○
•
Have gametophyte(multi haploid) which is the familiar photosynthetic form and sporophyte(multi diploid)
•
In non vascular gametophyte is larger and longer lived than sporophyte but other plants have it much different
•
Reproduction
Haploid gametophyte produces the gametes in archegonia and antheridia
○
Sperm must swim or be splashed by rain into an archegonium to fertilize eggs and then zygotes develops
into diploid sporophyte
○
•
Types of Nonvascular Land Plants
Liverworts
Have root like cells called rhizoids with small thin cuticles
○
Can have both asexual and sexual reproductions
○
Sperm are released during rain by shooting out to fertilize eggs in atmosphere
○
•
Mosses
Filamentous, gametophyte is leafy dominant, sporophyte only grows apically at the tip
○
•
Hornworts
Hornlike sporophytes that can reach 20 cm in height
○
Gametophytes are flat plats that are just a few cells thick
○
Sporophyte and gametophyte both independent
○
•
Non-Vascular Plants (15)
Friday, February 2, 2018
12:05 PM
Document Summary
Difficulties: drying out/losing water, spreading spores, performing gas exchange for co2. Cuticle - waxy coating to prevent water loss. Mutualisms with fungi that promote nutrient uptake (mycorrhizae) u. Not a monophyletic group; includes liverworts, mosses and hornworts. No vascular transport system so can"t grow tall and have no rigidity to support large g. Must live in moist habitat because have a thin cuticle anyways. Lack true leaves and stems and roots but sometimes have analogous structures. Water transport through diffusion and capillary actions, very slow so can"t grow too l. Have gametophyte(multi haploid) which is the familiar photosynthetic form and sporophyt. In non vascular gametophyte is larger and longer lived than sporophyte but other plants ha. Haploid gametophyte produces the gametes in archegonia and antheridia. Sperm must swim or be splashed by rain into an archegonium to fertilize eggs and th into diploid sporophyte. Have root like cells called rhizoids with small thin cuticles.
