Marchantia berteroana
Lehm. & Lindenb.

Family : Marchantiaceae
Common name
: umbrella liverwort (Eng.)

M. berteroana male plant with antheridia and gemmae cups Photo: S. Perold
M. berteroana male plant with antheridia and gemmae cups Photo© S. Perold

Marchantia berteroana is of one the most attractive and relatively large liverworts in South Africa. It thrives in constantly damp, shaded areas.

Description
What is a liverwort? A liverwort is a small leafless, flowerless, spore-producing plant. Liverworts were the first of the early green land plants to evolve (after algae and before the ferns), about 500 million years ago, making them the oldest living land plants! Liverworts are grouped into three main groups according to their structure: the simple thalloid, complex thalloid and leafy liverworts.

Marchantia belongs to the complex thalloid group.The Marchantia thallus (plant body) is a flattened strap-like structure, 325 –925 µm thick, divided into three layers: the upper layer with pores (under a lens it can be seen to be dotted with closely crowded, whitish pores) with smooth, somewhat glossy surface, the middle layer with air pockets and chloroplast-containing cells, and the lower layer that stores carbohydrates. The thallus of Marchantia berteroana is yellow-green to green or reddish-brown, 600–900 µm thick, with branches up to 20 mm long and about 12 mm wide with wavy margins. The thallus has scales on the lower surface (ventral scales) that extend nearly to the margins, and rhizoids (hair-like structures that act as roots) with which it attaches to its substrate.

The life cycle is divided into two phases alternating with each other: the haploid (with a single set of unpaired chromosomes) gametophyte phase and the diploid (with paired chromosomes and therefore with twice the haploid number) sporophyte phase. The gametophyte phase is the dominant phase which is actually the green flat plant that you see. The gametophyte is responsible for all the metabolic functions, e.g. photosynthesis, gas exchange and water absorption. During the sporophyte phase sexual reproduction takes place.

M. berteroana is dioicous, which means that the male and female gametangia (sex organs) are formed on separate plants. The male and female plants can be easily identified by their gametangia which are very distinct structurally and these are produced from the apex of the terminal segment of the main or short lateral branch. The male gametangia, called antheridia, are stalked disk-like structures that produce sperms. The antheridiophore (stalk of antheridium) is about 30 mm long and arises in August. The antheridial disk, on top of the stalk, is up to 10 mm wide and shallowly dissected into 8 or 9 symmetrical lobes which have brownish or colourless margins. The female gametangia, called archegonia, are stalked umbrella-like structures that produce eggs. The archegoniophore (stalk of archegonium) is about 80 mm long and it appears in September. The archegonial umbrella, on top of the stalk, is called carpocephalum and is up to 10 mm wide, dorsally (above) with small round median projections, and deeply divided into 9 linear rays. This sporophytic phase begins in the spring and continues through the summer months.

Marchantia berteroana antheridia Marchantia berteroana female plant
Marchantia berteroana antheridia
(male gametangia) © Bluetier.org
Marchantia berteroana female plant
with archegonia © Bluetier.org

M. berteroana can reproduce sexually or asexually. In sexual reproduction water is required for fertilization to take place. The sperm cell has multiple flagella (long whip-like outgrowths) that propel it forward to reach the archegonium. When it reaches the archegonium it swims through the neck and fertilizes the egg at the base of the archegonium, and a zygote is formed, the first cell of the diploid sporophyte. The sporophyte is formed and is attached to the mother gametophyte by a foot through which the nutrients are passed between the sporophyte and the gametophyte. The sporophyte is completely dependent on a gametophyte for survival. The sporophyte also has a stalk, called seta, that connects the foot to the sporangium (capsule). Inside the sporangium the spores are produced and among them are yellow-brown, bispiral (in a double spiral) structures, called elaters, whose function is to help in the release of the spores. The stalk is fragile and remains short until the sporangium has fully matured and the spores are ready for release.

Marchantia berteroana female plant Marchantia berteroana female plant
with archegonia © Bluetier.org

Once the sporangium has matured, the stalk elongates by absorbing water, stretching its cells, growing taller so that it reaches high above the mother gametophyte. The sporangium then breaks open exposing the spores and the elaters. The elaters wiggle, stretch and bend according to the humidity in the surrounding air, thus aiding the spores to disperse. After spore dispersal the fragile stalk disintegrates. This is a very short process. A magnifying glass might come handy if you are lucky enough to see this fascinating process happening right before your eyes.

Marchantia berteroana gemmae cups

Marchantia berteroana gemmae cups
© Bluetier.org

For asexual reproduction to take place M. berteroana produces special, fun-to-look-at, cup-like structures, called gemmae cups, located on the upper surface of the gametophyte, 4 mm wide and 3 mm high. Minute, multicellular, disc-shaped structures called gemmae are produced on the floor of the gemma cups, each attached by a minute stalk and showing two lateral growing-points. When mature, the gemmae break away from their stalks. When water or rain droplets hit inside the gemmae cups, they splash out the gemmae which, when landed in favourable substrate (e.g. damp soil), develop directly into a new plant.

Conservation status
Marchantia is not listed among the threatened liverworts according to the IUCN SSC Bryophyte Specialist Group.

Distribution and habitat
M. berteroana is prevalent in the winter rainfall region of South Africa, in the Western Cape province and the western part of the Eastern Cape. It also grows in KwaZulu-Natal, Mpumalanga and Limpopo provinces which receive summer rain. It grows in constantly moist environments, in fresh water, waterfall splash zones, forest floor and stream banks. Liverworts do not grow in salty aquatic habitats and few grow on water-limited microhabitats, e.g. rock surface.

Derivation of name and historical aspects
The word ‘wort' refers to a plant and ‘liver' refers to the fact that the early herbalists believed that the structure of this plant resembles a liver and presumed that it could be used to cure liver ailments. Liverworts are also referred to as hepatics, from the Latin word hepaticus for ‘belonging to the liver'. The family name, Marchantiaceae refers to the liverworts with prostrate and usually dichotomously (into two) branched thalli. The genus name was first used by the French botanist Marchant in 1713 in memory of his father (Campbell 1965). The specific name, berteroana was named after Carlo Giuseppe Bertero, a 19th century Italian physician and botanist. There are five species of Marchantia in southern Africa.

Ecology
Spore and gemmae dispersal is by means of water. The low-lying, flattened stature gives this plant an advantage as it is closer to water source. Like most bryophytes, the liverworts play a very significant role in various ecological systems. They play a main role in nutrient cycles as effective rainfall receptors and in prevention of soil erosion by binding and stabilising soil. They form a major component of humus. The liverworts are in close association with climatically sensitive habitats, and thus serve as potential indicators of climate change in the ecosystem.

Uses and cultural aspects
Liverworts are of little known economic value. Ancient herbalists believed that the liver-like shape of this plant denotes that it can be used to cure liver ailments according to a philosophy called Doctrine of Signatures. This belief has not been scientifically proven.

Growing Marchantia berteroana

Liverworts are best used in rock or shade gardens, in frequently moist, humus-rich soil and in partial to preferably full shade. Some people see the liverworts as weeds and pests but they are in fact a wonderful ground cover.

Growing this liverwort should not be difficult. There is no need for fertilizers. The first step is to loosen the soil with a garden tiller to a depth of 200 mm in the early summer. Place the liverwort spores on the bare soil, spacing them 150 to 300 mm apart. Rake about 6 mm layer of soil over the spores. Water until the soil settles. Use leaves as mulch in autumn. Covering your patch or pots with net keeps the birds away, at least until your plants are well established.

High humidity suppresses gemmae cup production in M. berteroana and high temperaturez (ca. 15°C) promotes production of more gemma cups (Chopra & Kumra 1988). In her experience with growing Marchantia plants, Martin (pers comm. 2012) states that if exposed to direct sun on a hot day, the trays of her Marchantia plants turn brown in an afternoon and do not recover. She therefore supplements rainfall with 2–5 minutes of three different watering sessions each day during spring, summer and autumn. Her supplemental watering is sporadic in the winter due to freezing conditions as it seems that liverworts tolerate freezing conditions well. She is always happy to share her joy of gardening with bryophytes and is writing a book on moss gardening which will include mention of liverworts as well.

References and further reading

 

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Nonkululo Phephu
Pretoria National Herbarium
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