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# BIOL 108 Introduction to Biological Diversity
## Topic 14: Non-vascular Plants
> Lecture A2
> Yan-yin Wang
Phylogenetic Framework of Bryophytes
Bryophytes : An informal name of mosses, liverworts, or hornworts; non-vascular plants that live on land but lacks some of the terrestrial adaptations of vascular plants .
Phylogenetically, bryophytes diverged earliest from the common ancestor of land plants.
Bryophytes form a paraphyletic group with three phyla of small non-vascular plants.
They are also called herbaceous plants.
> Campbell, N. A., Reece, J. B., Urry, L. A., Cain, M. L., Wasserman, S. A., Minorsky, P. V., & Jackson, R. B. (2024). Campbell biology (4th Canadian ed.). Pearson.
> Phylogeny of Embryophyta.
Characteristics of Bryophytes
Absence of true vascular tissue and lignin.
The size of bryophytes is limited due to:
Lack of structural support
Lack of a complex system for nutrient transportation
Absence of true roots.
Water is absorbed through the surfaces of the plant body, which are anchored by filaments of cells called
rhizoids .
Bryophytes need to live in habitats rich in water.
Absence of true leaves.
Rhizoid in the liverwort Marchantia polymorpha (top) and leaves in the moss Physcomitrium patens (bottom). .
Lin, W., Wang, Y., Coudert, Y., & Kierzkowski, D. (2021). Leaf morphogenesis: insights from the moss Physcomitrium patens. Frontiers in Plant Science , 12 , 736212.
Graham, L. E., Wilcox, L. W., Cook, M. E., & Gensel, P. G. (2004). Resistant tissues of modern marchantioid liverworts resemble enigmatic Early Paleozoic microfossils. Proceedings of the National Academy of Sciences , 101 (30), 11025-11029. Characteristics of Bryophytes
Sporophytes (multicellular, 2n) are unbranched.
Stoma is absent in liverworts and present in mosses and hornworts.
Gametophytes (multicellular, 1n) are larger and longer-living than sporophytes.
The free-living haploid stage is the most dominant phase of the life cycle.
The survival of sporophytes depends on gametophytes.
Sporophytes remains physically attached to gametophytes.
Gametophytes supply necessary nutrients for sporophytes.
# Life cycle of the hornwort Anthoceros agrestis .
> Szvnyi, P., Frangedakis, E., Ricca, M., Quandt, D., Wicke, S., & Langdale, J. A. (2015). Establishment of Anthoceros agrestis as a model species for studying the biology of hornworts. BMC plant biology ,15 , 1-7.
> 2 mm 2 mm 200 m
> 40 m100 m
Typical Life Cycle of a Moss
Gametophytes (multicellular, 1n) stage:
Haploid spores (1n) are released.
Spores germinate into gametophytes (1n) composed of protonema and gametophore.
Protonemata : Thread-like or filamentous network of cells rich in chloroplasts.
Protonemata develop into gametophyte
composed of leave-like appendages.
Gametophytes become matured, often as separate male and female plants, each of which produce gametangia (i.e., sperms and eggs).
Gametes are produced by mitosis.
Sperms from an antheridium fertalise eggs in an archegonium.
Water is necessary for the sperms to swim into the archegonium of the female. Gametophyte.
> Life cycle of a moss (required!).
> Campbell, N. A., Reece, J. B., Urry, L. A., Cain, M. L., Wasserman, S. A., Minorsky, P. V., & Jackson, R. B. (2024). Campbell biology (4th Canadian ed.). Pearson.
Typical Life Cycle of a Moss
Sporophytes (multicellular, 2n) stage:
Diploid zygote (2n) is formed from fertalisation.
Under the nourishment of the female gametophyte, the zygote develops into a diploid embryo (2n )and the diploid sporophyte (2n) is retained.
The retained sporophyte (2n) grows out of the archegonium of the female gametophyte.
Bryophytes have the smallest sporophytes of all land plants.
Sporophyte matures and develops a sporangium.
Spores are developed by meiosis within the sporangia.
Spores are released and dispersed in the air.
The stage from a spore to a gametophyte is considered a process of asexual reproduction.
> Life cycle of a moss (required!).
> Campbell, N. A., Reece, J. B., Urry, L. A., Cain, M. L., Wasserman, S. A., Minorsky, P. V., & Jackson, R. B. (2024). Campbell biology (4th Canadian ed.). Pearson.
Major Groups of Bryophytes
Liverworts (phylum Hepatophyta) : A division of non-vascular plants with approximately 9,000 extant species.
The name Hepatophyta is derived from hepato for liver and phyt for plants.
Characteristics:
Absence of xylem and phloem
Absence of stoma
Presence of a unique organelle called oil bodies
Ecological significance:
Liverworts stabilise soils in moist habitats.
Liverworts show antimicrobial and antifungal properties.
# The common liverwort Marchantia polymorpha surround by mosses (top), and oil bodies within cells (bottom).
> https://earthlingnature.wordpress.com/tag/liverworts/
> Singh, D., Dey, M., & Singh, D. K. (2012). Studies on Oil-odies in Some Liverworts from Sikkim, Eastern Himalaya, India.
Major Groups of Bryophytes
Mosses (phylum Bryophyta) : A division of
non-vascular plants with approximately 15,000 extant species.
The name Bryophyta is derived from bryo for moss and phyt for plants.
Bryophyta contains only the moss phylum, but bryophytes include all non-vascular plants.
Characteristics:
Absence of xylem and phloem
Presence of stoma
Ecological significance:
Mosses facilitate water retention.
The peat moss Sphagnum can be used to condition soil, and they may be used as materials for biofuel.
# The moss Polytrichastrum formosum (top left), the stomata in mosses (top right), and the moss fuel cell (bottom).
> Ligrone, R., Duckett, J. G., & Renzaglia, K. S. (2012). Major transitions in the evolution of early land plants: a bryological perspective. Annals of botany ,109 (5), 851-871.
> https://hackaday.io/project/185108/gallery#bab12be82ac1a7347fdabcfb95eefa0d
Major Groups of Bryophytes
Hornworts (phylum Anthocerophyta) : A smaller division of non-vascular plants with approximately 100 extant species.
The name Anthocerophyta is derived from antho for flower and phyt for plants.
Characteristics:
Absence of xylem and phloem
Presence of stoma
Presence of a single, large chloroplast
Absence of seta to support sporangium
Ecological significance:
Hornworts form symbiotic relationship with cyanobacteria.
# Sporophyte in the hornwort Anthoceros (top left), the sporophyte in the moss Polytrichum commune (top right), and the large chloroplast in the hornwort Anthoceros agrestis (bottom).
> Campbell, N. A., Reece, J. B., Urry, L. A., Cain, M. L., Wasserman, S. A., Minorsky, P. V., & Jackson, R. B. (2024).
> Campbell biology (4th Canadian ed.). Pearson.
> Frangedakis, E., Shimamura, M., Villarreal, J. C., Li, F. W., Tomaselli, M., Waller, M., ... & Szvnyi, P. (2021). The hornworts: morphology, evolution and development. New Phytologist ,229 (2), 735-754.
Some Reflective Questions (Not an Exhaustive List for Exam!)
How shared characteristics position bryophytes on a phylogeny leading to vascular plants?
Can you describe a typical life cycle of bryophytes?
How may we distinguish the main groups of bryophytes?