Conocephalum is a genus of complex thalloid liverworts in the order Marchantiales and is the only extant genus in the family Conocephalaceae.[AKIYAMA, H. (2022). Morphological and ecological diversification of Conocephalum conicum complex in Japan and Taiwan. Humans Nat, 32, 1-45.] Some species of Conocephalum are assigned to the Conocephalum conicum complex, which includes several cryptic species.
Species of Conocephalum are relatively common
Conocephalum has a relatively large thallus
Classification and taxonomy
Some species of
Conocephalum are placed in the
Conocephalum conicum complex, which includes several cryptic species.
Consequently, it has been challenging to identify the exact number of species in this genus.
Cryptic species refers to a species which demonstrates a genetic difference but lacks morphological differences. Within liverworts, cryptic species are suggested to be related to both geographical disjunction and to reproductive biology in combination with isolation and habitat differentiation.
Molecular research has indicated that Conocephalum comprises a complex of six cryptic species (A, C, F, J, L and S).
Species
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Conocephalum conicum complex – includes several cryptic species:
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Conocephalum conicum
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Conocephalum salebrosum
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Conocephalum orientalis
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Conocephalum purpureorubum
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Conocephalum toyotae
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Conocephalum supradecompositum
Distribution
Species of
Conocephalum are distributed throughout North America, Europe and East Asia.
displays the widest distribution and is found throughout North America,
Europe and Asia.
In North America,
C. salebrosum occurs throughout Canada and parts of the United States and has also been reported from Russia.
In contrast to
C. salebrosum, C. conicum is found throughout Europe
and has been recorded in Norway, Finland, Great Britain, Ireland, Belgium, France, Germany, Czech Republic, Austria, Hungary, Romania, Italy, Portugal, Spain, Croatia, Bulgaria, Greece, Ukraine, Poland and Russia.
The species C. supradecompositum is more restricted in its distribution and is mainly found in China and Japan.
Habitat
Species of
Conocephalum often occur in moist and shaded habitats.
species also grow in specialized micro-habitats near both running and standing water.
is often found in open woodlands, sandy banks, wet rocks and cliffs and moist soils.
Both
C. conicum and
C. salebrosum are strongly associated with
calcareous substrates.
It has also been suggested that
C. salebrosum is likely more tolerant of desiccation than
C. conicum.
[Cros, R. M., & Buczkowska, K. (2009). Conocephalum salebrosum (Marchantiopsida) new to Spain. Cryptogamie, 30(1), 203.]
Morphology
Conocephalum conicum and
C. salebrosum share some similarities in morphological characteristics, in addition to having their own unique traits which help distinguish the two species.
Gametophyte
The vegetative structure of
Conocephalum is a thallus which has the appearance of a flattened body of plant tissue.
The thallus is irregularly branched
and relatively large, reaching lengths of roughly 20-24 cm.
In contrast to
C. conicum and
C. salebrosum, the thallus of
C. supradecompositum is relatively small, measuring 2-3 cm long.
The thallus grows by developing lobes
which wither away as the plant matures.
Plants of
C. salebrosum often grow by overlapping lobes, sometimes creating large mats.
Species of Conocephalum have a thallus that is either dull in appearance, such as C. salebrosum, or distinctly shiny, such as C. conicum.
The underside of the thallus has both Rhizoid and scales.
Complex oil bodies
Liverworts cells often contain complex oil bodies.
The oil bodies are intracellular
Organelle bounded by a single membrane.
The oil bodies have been known to contain a variety of unique
Phytochemical, such as
Terpene and
Flavonoid.
The function of oil bodies is still poorly understood.
It has been suggested that oil bodies might function as a deterrent to
Herbivore or could protect from cold temperatures or harmful ultraviolet radiation.
Sporophyte
The
sporophyte consists of an unbranched stalk called a seta, which bears a terminal spore capsule called a
sporangium.
The sporangia of
Conocephalum are borne beneath stalked
Gametophyte structures called archegoniophores.
In contrast to mosses, the sporophyte matures before the seta elongates.
Unlike mosses, liverwort sporophytes lack stomata, a columella and
Peristome.
Life cycle
The life cycles of liverworts involves alternating
haploid gametophyte and
diploid sporophyte generations. The
gametophyte generation is more dominant, while the sporophyte generation is relatively short-lived. The gametophyte produces haploid
Gamete,
egg and
sperm, which fuse to form a diploid
zygote. The zygote then develops into a sporophyte which ultimately produces haploid
Spore through
meiosis. The sporophyte requires nutrients supplied by the gametophyte to sustain growth and development.
The life cycle of Marchantia liverworts also applies to Conocephalum, with the exception that Conocephalum lacks a stalked Antheridiophone and instead has small flat antheridial heads on the surface of the thallus.
Reproduction
Liverworts reproduce through both sexual and asexual reproduction.
In natural populations, the high genetic variation observed suggests that sexual reproduction might dominate. Species of
Conocephalum are
Dioicy,
meaning that the male and female reproductive structures are produced on separate plants.
Sexual reproduction
In
Conocephalum the male and female reproductive parts are embedded in receptacles on separate plants. On male plants, the receptacle is slightly raised, lacking a stalk, and often circular or oval shaped.
Antheridium are embedded in the receptacle
and at maturity the sperm is released into the air.
In contrast, on female plants the receptacles are dome-shaped, with several drooping lobes at the end of an erect stalk. The receptacles are often described as a tiny umbrella, with the
Archegonium beneath.
Gametophytes produce eggs and sperm in the archegonia and antheridia, respectively.
Conocephalum elaters are unique and display a wide range of variability in shape, size and number. Often the abundance of elaters within a capsule are 2-3 times more abundant than spores.
Asexual reproduction
The production of gemmae is a common method of asexual reproduction in liverworts.
Gemmae are small packets of tissue consisting of haploid cells that are genetically identical with those of the parent plant. They are dispersed by rainfall and ultimately grow into new individuals.
In
C. conicum, gemmae are located on the lower layers of the thallus and are released as the thallus degrades.
In contrast,
C. salebrosum does not produce gemmae.
Vegetative reproduction can occur when a piece of the thallus breaks off and is transported away from the parent plant.
Conocephalum species are Perennial plant, meaning that they can overwinter and produce new growth in the spring. These new buds are covered and protected by small scales.
Biochemistry
Many liverworts produce different terpenes and aromatic compounds.
and aromatic compounds are often accumulated within the oil bodies of many liverworts, including
Conocephalum. Within
Conocephalum, considerable variation in species have been identified based on chemical composition and these compounds been used to identify different cryptic species.
Three different groups of Conocephalum were identified baed on their unique primary volatile compounds. For example, the compound cubebol, a sesquiterpene alcohol, is characteristic of C. salebrosum.
A unique sesquiterpene alcohol known as conocephalenol was identified and extracted from C. conicum.
Associations with other species
Fungal interactions
Conocephalum can form associations with
Fungus that are similar to the
Mycorrhiza associations observed
Vascular plant. Molecular analyses demonstrated that
Conocephalum contained fungal
Endophyte from the group of fungi known as the
Glomeromycota.
Conocephalum conicum often colonizes bare soils or rocky substrates, where mineral nutrients can often be limiting. The fungal endophyte establishes a complex relationship with C. conicum, which is characterized by the formation of arbuscules. These fungi form a highly branched mycelium outside of the plant which then colonize the outside of the rhizoids and pass into the gametophyte. The fungal infection induces grown of fungal hypha within the host cells of C. conicum. This association of the fungal hypha with the hosts Plastid suggests that photosynthates produced through photosynthesis in C. conicum are likely transferred to the fungus. A similar situation regarding this fungal association has also been identified in the thalloid liverwort Pellia epiphylla. Although these associations are common in vascular plants, they have rarely been described in non-vascular plants.
Animal interactions
Herbivory
Approximately 25 species of
moth which are
Endemism to East Asia associate exclusively with
Conocephalum. The larval stage of
Epimartyria pardella moths feed on
C. conicum.
In addition, the fungal species
Loreleia marchantiae also feeds on
C. conicum.
Pathogens
The fungal
pathogen belonging to the genus
Pythium has often been isolated from infected rhizoids and thallus of
Conocephalum. is another fungal pathogen that has been associated with
C. conicum.
Human applications
Conocephalum as a bioindicator for pollution
Conocephalum conicum has been identified as being tolerant of
heavy metals and has therefore been suggested to have a possible role as a
bioindicator for
pollution.
Conocephalum conicum takes up
from both the soil and the atmosphere. Therefore, heavy metals contamination of
C. conicum is related not only to air pollution, but environmental contamination from different sources.
Recent research has also examined
C. conicum as a bioindicator for
cadmium pollution. Cadmium a toxic
metal and considered the third highest contaminant, after mercury and
lead.
Conocephalum conicum was shown to respond to cadmium stress by changing its biological activity. These biological changes could be used as
Biomarker for cadmium pollution.
Anti-fungal activity
Conocephalum conicum has been suggested to have a possible role in the management of food borne disease caused by species of
Aspergillus fungi.
Aspergillus produces highly potent
Toxin,
Carcinogen, referred to as
Aflatoxin Aflatoxins are harmful both plants and animals.
Aspergillus can cause disease in many important
Crop, which can ultimately cause disease in humans.
Conocephalum has been shown to have a variety of bioactive compounds which promote anti-fungal property against
Aspergillus.
Ethnomedicine
Throughout North America, China and India, liverworts such as
Conocephalum have been used for
Ethnomedicine purposes.
Conocephalum is known to be important to Bhotia, Raji, Tharus and Boxas tribes in
Pithoragarh district of Kumaon Himalaya.
Conocephalum conicum is used to treat burns, and the extract of
C. conicum is also used in treating
Gallstone.
Conocephalum has also demonstrated
antidote activity against
Snake venom Snakebite. The role of
Conocephalum regarding modern medicine has yet to be investigated.
Cosmetic industry
Liverworts often contain highly
Pungency compounds.
species often exude an
Odor that is characteristic of
turpentine. The odour is thought to be related to the presence of monoterpenoids. The compound conocephalenol is widely used in the cosmetic industry for its
Odorant properties.
Photo gallery
File:Conocephalum conicum (g, 145025-474547) 6046.JPG| Conocephalum conicum, the thallus is distinctly shiny
File:Conocephalum salebrosum (a, 145855-475042) 7776.JPG| Conocephalum salebrosum, the thallus is dull in appearance
File:Conocephalum conicum (e, 144739-474742) 1022.jpg| Conocephalum conicum, thallus
File:Liverwort - Flickr - treegrow (1).jpg| Conocephalum conicum, air pores visible on the upper surface of the thallus
File:Conocephalum salebrosum (a, 145855-475042) 7808.JPG| Conocephalum salebrosum, thallus cross section showing photosynthetic cells
File:Conocephalum salebrosum (a, 145855-475042) 7810.JPG| Conocephalum salebrosum, thallus cross section showing photosynthetic cells
File:Conocephalum salebrosum (a, 145855-475042) 7806.JPG| Conocephalum conicum, air pore present in the upper surface of the thallus
File:Conocephalum conicum (c, 144707-474823) 1912.jpg| Conocephalum conicum, sporophytes (black) hanging beneath the umbrella-shaped, stalked archegoniophores
File:Conocephalum salebrosum (b, 142632-474029) 4442.JPG| Conocephalum salebrosum, sporophytes (black) hanging beneath the umbrella-shaped, stalked archegoniophores
File:Conocephalum conicum (f, 145046-474908) 3102.JPG| Conocephalum conicum, sporophytes (black) hanging beneath the archegoniophores
File:Conocephalum conicum jagoke03.jpg| Conocephalum conicum, antheridium
File:Conocephalum salebrosum (b, 142632-474029) 4502.JPG| Conocephalum salebrosum, spores and elaters
File:Conocephalum salebrosum (b, 142632-474029) 4504.JPG| Conocephalum salebrosum, spores and elaters
File:Conocephalum salebrosum (b, 142632-474029) 4496.JPG| Conocephalum salebrosum, ir pore present in the upper surface of the thallus
