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Nonvascular Plants: Mosses, Liverworts, and Hornworts (Division Bryophyta:…
Nonvascular Plants: Mosses, Liverworts, and Hornworts
Concepts
Nonvascular plants
Have neither vascular tissues nor seeds
Vascular cryptogams
Have vascular tissue but not seeds
Spermatophytes
Have both vascular tissue and seeds
Characters of non vascular plants
Have multicellular sporangia and gametangia
Bodies are composed of true parenchyma
Almost exclusively terrestrial
Classification of nonvascular plants
Three distinct divisions
Liverworts
Mosses
Hornworts
Division Bryophyta: mosses
The gametophyte generation
Gametophores
Leafy stems
Hydroids
Cells that compose the innermost cortex
Leptoids
Cells that resemble sieve cells
Rhizoids
At the base of the stem
Small, multicellular trichome-like structures
Penetrate the surface of the substrate
Protonema
A branched system of similar cells
Antheridia
Microgametangia where sperm are produced
Archegonia
Megagametangia where eggs occur
The sporophyte generation
Foot
Small bulbous tissue at bottom of the archegonium
Capsule
Simple apical sporangium
Operculum
Apex of the sporangium differentiates as a caplike lid
Peristome teeth
Results from elaborate and precise cell breakage
Calyptra
Covers the apex of the sporangium
Metabolism and ecology
It is hard for mosses to retain water
They live is constantly moist habitats
Division Anthocerophyta: hornworts
The gametophyte generation
Antheridial initials are not surface cells
Cells lining a special mucilage chamber grow into it and become antheridia
The sporophyte generation
Just above the foot is a meristem that continuously produces new sporangium tissues
Division Hepatophyta: liverworts
The gametophyte generation
Two basic groups
Leafy liverworts
Thallose liverworts
Body is referred to as the thallus
Large air pores
Antheridiophore
Umbrella-shaped outgrowth produced by male gametophores
Archegoniophores
Apex is a set of radiating fingers that project outward and droop downward
The sporophyte generation
Elaters
Single, elongate cells with spring-shaped walls
