''Tmesipteris horomaka'', commonly known as the Banks Peninsula fork fern, is a

fern ally Fern allies are a diverse group of seedless vascular plants that are not true ferns. Like ferns, a fern ally disperses by shedding spores to initiate an alternation of generations. Classification Originally, three or four groups of plants w ...

endemic Endemism is the state of a species being found only in a single defined geographic location, such as an island, state, nation, country or other defined zone; organisms that are indigenous to a place are not endemic to it if they are also foun ...

New Zealand New Zealand () is an island country in the southwestern Pacific Ocean. It consists of two main landmasses—the North Island () and the South Island ()—and List of islands of New Zealand, over 600 smaller islands. It is the List of isla ...

Description

''Tmesipteris horomaka'' is usually found on the stem of the tree ferns, i.e.,

epiphytic An epiphyte is a plant or plant-like organism that grows on the surface of another plant and derives its moisture and nutrients from the air, rain, water (in marine environments) or from debris accumulating around it. The plants on which epiphyt ...

fern or sometimes found on the ground, or soil from decomposing logs, i.e., terrestrial fern.Brownsey, P. J., & Perrie, L. R. (2014). Flora of New Zealand Ferns and Lycophytes. December. https://doi.org/10.7931/J2KW5CXJ Many stems of ''Tmesipteris horomaka'' can be found on a single fern tree, but it is hard to tell whether they belong to single individual fern, as Tmesipteris plants have creeping rootstock from which various shoots may arise.Perrie, L. R., Brownsey, P. J., & Lovis, J. D. (2010). ''Tmesipteris horomaka'', a new octoploid species from Banks Peninsula. New Zealand Journal of Botany. https://doi.org/10.1080/00288251003640010 It has continuous creeping rootstock with the aerial stem grows to a length that ranges between 60 and 510 mm and with a width of 15 to 35 mm. The leaves are rounded at the apex and have a small spike, known as mucron at the top of the leaves, which grows to the length of 10 to 25 mm and has a width that ranges between 2.5 and 6.5 mm. The structure of this species is somewhat in between of ''T. elongata'' and ''T. tannensis''. The difference between ''T. horomaka'' and ''T. tannensis'' is that of the placement of the spore-producing synangia, and it differs from ''T. elongata'' by having a truncate leaf with a notch at the apex of the leaves. The characteristics of ''Tmesipteris horomaka'' is further differentiated from that of its parent by its spore size both of which are tetraploid while ''T. horomaka'' is octoploid.

Habitat

''Tmesipteris horomaka'' is an epiphyte in nature; they are usually found of hanging from the trunk of tree ferns or other trees in the forest for infrastructure and support. The initial observation of ''T. horomaka'' was as an epiphyte around the stem of the tree fern; however, a sample which came from

Port Hills The Port Hills () are a range of hills in Canterbury Region of New Zealand, so named because they lie between the city of Christchurch and its port at Lyttelton, New Zealand, Lyttelton. They are an eroded remnant of the Banks Peninsula Volcano ...

registered it to be found on the decaying matter of Phormium (flax) which was on the southeast cliff face. The tree ferns that can host ''T. horomaka'' are ''Cyathea dealbata'', ''C. smithii'', and ''Dicksonia squarrosa'' are found in podocarp, broadleaved, and beech forest. So far it is only found in New Zealand with the population found in the area of

Banks Peninsula Banks Peninsula () is a rocky peninsula on the east coast of the South Island of New Zealand that was formed by two now-extinct volcanoes. It has an area of approximately . It includes two large deep-water harbours — Lyttelton Harbour a ...

and the Port Hills near

Christchurch Christchurch (; ) is the largest city in the South Island and the List of cities in New Zealand, second-largest city by urban area population in New Zealand. Christchurch has an urban population of , and a metropolitan population of over hal ...

Ecology

Life cycle/phenology

There are two distinct changes that take place during the life of a fern which belongs to a group of vascular plants, i.e., from the sporophytic phase to a gametophytic phase.Walker et al., 2019. Fern. Retrieved April 18, 2020, from https://www.britannica.com/plant/fern The spores of the fern are haploid and are produced in an organ called sporangia, which can be found on the leaves of the fern, also called fronds. A tiny portion of the spores gets dispersed into the atmosphere due to the current of the wind and falls inappropriate site to form a gametophyte. The fertilization takes place when the eggs and sperm are produced on the different gametophyte, and the results are placed in the tissue of prothallium until the embryo breaks its dormancy and cell division takes place, which finally leads to the development of gametophyte.

Threats

Bio Status: Endemic ''Tmesipteris horomaka'' was considered as a threatened species by the Department of Conservation and was receiving extra support for the management. The total population of ''Tmesipteris horomaka'' was found to be less than 250 of mature individuals, which brings them to the criteria of endangered species, this was also classified under lack of data and currently found in only one location. As this species is newly discovered, further survey is needed, and so far, through the preliminary population survey, the biggest threat to it is the safety and survival of its host plant.

Other information

''Tmesipteris horomaka'' was discovered when researchers Leon R Perrie, Patrick J Brownsey were on their survey researching the chromosome number in two species of the Tmesipteris, which ended by finding a new octoploid fern on the Bank Peninsula. This species was a cross between a locally occurring species ''T. elengata'' and ''T. tannensis'', and the characteristic of the new species was utterly different from that of its parents. The prothalli, also known as gametophytes, are hard to find. They are rarely found in the environment. This is due to the dense population of Tmesipteris, the location it grows, and the dormancy period before it grows as an individual plantBrown, J. (1918). Prothallia of Tmesipteris. The Plant World, 21(9), 241-243. Retrieved April 19, 2020, Retrieved from www.jstor.org/stable/43477715

References

{{Taxonbar, from=Q17249545 Psilotaceae Ferns of New Zealand Epiphytes Plants described in 2010