Conocephalum туқымдасы: түрлері мен таралуы

Genus of plants

Conocephalum is a genus of complex thalloid liverworts in the order Marchantiales and is the only extant genus in the family Conocephalaceae. Some species of Conocephalum are assigned to the Conocephalum conicum complex, which includes several cryptic species. The species Conocephalum conicum is named for its cone shaped reproductive structures, called archegoniophores. Common names include snakeskin liverwort, great scented liverwort and cat tongue liverwort. Species of Conocephalum are relatively common Conocephalum often occurs in moist and shaded habitats Species of Conocephalum produce different terpenes and aromatic compounds. Molecular research has indicated that Conocephalum comprises a complex of six cryptic species (A, C, F, J, L and S). In 2005 C. conicum cryptic species S was described as a separate species, C. salebrosum. Conocephalum salebrosum displays the widest distribution and is found throughout North America, In North America, C. salebrosum occurs throughout Canada and parts of the United States and has also been reported from Russia. The species C. supradecompositum is more restricted in its distribution and is mainly found in China and Japan. Regarding the most recently described species of Conocephalum, C. purpureorubum has been observed in Japan, China, Taiwan and South Korea and C. orientalis has been found in Japan and Taiwan. Conocephalum species also grow in specialized micro habitats near both running and standing water.

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. The thallus is irregularly branched Plants of C. salebrosum often grow by overlapping lobes, sometimes creating large mats. In the middle of each air chamber is a white ringed pore. The short rhizoids are thought to play a role in absorbing water and nutrients. In contrast, the longer rhizoids help anchor the thallus to the underlying substrate. The rhizoids are single celled, in contrast to the multicellular rhizoids found in mosses. The oil bodies are intracellular organelles bounded by a single membrane. The oil bodies have been known to contain a variety of unique phytochemicals, such as terpenes and flavonoids. Unlike mosses, liverwort sporophytes lack stomata, a columella and peristome teeth.

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. Antheridia are embedded in the receptacle 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 archegonia beneath. 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. Elaters form from an initial mother cell which develops into a diploid cell with spiral thickenings. In contrast, spores develop from an initial diploid mother cell that ultimately forms haploid spores by meiosis. In C. conicum, gemmae are located on the lower layers of the thallus and are released as the thallus degrades. Conocephalum species are perennial, meaning that they can overwinter and produce new growth in the spring. These new buds are covered and protected by small scales. Terpenoids 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.

Conocephalum can form associations with fungi that are similar to the mycorrhizal associations observed vascular plants. Molecular analyses demonstrated that Conocephalum contained fungal endophytes 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 plastids 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.

Approximately 25 species of moths which are endemic to East Asia associate exclusively with Conocephalum. In addition, the fungal species Loreleia marchantiae also feeds on C. conicum.

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 ions 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 biomarkers for cadmium pollution.

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 toxins, carcinogens, referred to as aflatoxins. Aflatoxins are harmful both plants and animals. Aspergillus can cause disease in many important crops, 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. Conocephalum species often exude an odour 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 odourant properties.