Liverworts (Phylum Marchantiophyta) are very primitive, non-vascular land plants, persisting in very moist (but not aquatic) environments. Liverworts are flattened, ribbon-like leaves with a waxy cuticle, and are held to their substrate with single-celled rhizoids, or root-like structures. Liverworts have a gametophyte-dominant life cycle, meaning the entire plant is typically haploid throughout their lives (unlike nearly all other plants). Due to this life cycle, liverworts must be fertilized in order to reproduce. Once fertilized, they reproduce via spores.

 

Thallose liverwort. The thallus is the ribbon-like leaves of the plant. Photo: Lairich Rig 2007. Source: Wikimedia Commons.  

Thallose liverwort. The thallus is the ribbon-like leaves of the plant. Photo: Lairich Rig 2007. Source: Wikimedia Commons.  

Thallose liverworts (Marchantia and Lunularia spp.) showing clonal plantlets in gemma cups. A gemma is a mass of cells, or a modified bud of tissue, that detaches from the parent and develops into a new individual. This type of asexual reproduction is referred to as fragmentation. It is a means of asexual propagation in plants. Photo: Avenue 2011. Source: Wikimedia Commons.  

Thallose liverworts (Marchantia and Lunularia spp.) showing clonal plantlets in gemma cups. A gemma is a mass of cells, or a modified bud of tissue, that detaches from the parent and develops into a new individual. This type of asexual reproduction is referred to as fragmentation. It is a means of asexual propagation in plants. Photo: Avenue 2011. Source: Wikimedia Commons.  

The star-shaped structures are the archaegonial heads of a thallose liverwort. The archaegonia hold  fertilized spores, whereas the antheridial head holds sperm.  Photo: J.F Gaffard 2004. Source: Wikimedia Commons.  

The star-shaped structures are the archaegonial heads of a thallose liverwort. The archaegonia hold  fertilized spores, whereas the antheridial head holds sperm. 

Photo: J.F Gaffard 2004. Source: Wikimedia Commons.  

Life cycle of a liverwort. Ilustration: LadyofHats 2005. Source: Wikimedia Commons.  

Life cycle of a liverwort. Ilustration: LadyofHats 2005. Source: Wikimedia Commons.