| Lettuce liverwort | |
|---|---|
 | |
Scientific classification  | |
| Kingdom: | Plantae |
| Division: | Marchantiophyta |
| Class: | Jungermanniopsida |
| Order: | Fossombroniales |
| Family: | Petalophyllaceae |
| Genus: | Petalophyllum |
| Species: | P. preissii |
| Binomial name | |
| Petalophyllum preissii Lehm. | |
Petalophyllum preissii, the lettuce liverwort, is a species of liverwort that is the type species of the family Petalophyllaceae. It is found in Australia and New Zealand, and is at risk of extinction in both countries.
Petalophyllum preissii is a species that forms a rosette with radiating ruffles of tissue on the upper side of the thallus that gives it a scale-like appearance. [2] [3] The thallus is roughly as long as it is wide, and the rhizoids of the species are clear or brown. [3] In its original description, the similarity of P. preissii to Fossombronia pusilla was noted, especially among male and young specimens. [4] It can be told apart from species in Fossombronia because they have much more narrow thalli, and lack a scaly upper side. [3] The elater cells in the sporophyte are thinner than those of its sister species Petalophyllum ralfsii . [5]
Petalophyllum preissii was described alongside P. ralfsii as founding members of the genus Petalophyllum by Johann Georg Christian Lehmann in 1844. [6] However, it was never clear which species was the type species of the genus. In 1972, P. preissii was explicitly selected as the type for the first time, and has been used as such since then. [7]
A 2014 report rejected Petalophyllum australe and treated it as a synonym of P. preissii. [8]
Lettuce liverwort is one of only a few hornwort and liverwort species in New Zealand that have been comprehensively surveyed. [9] In 2014, it was assessed as having fewer than 250 individuals in the country. The following year, only 36 plants were found in one population near the town of Kaikōura. [10] As such, the species is at a high risk of becoming extinct in New Zealand, and was assessed as Nationally Critical in the New Zealand Threat Classification System in 2014 and 2020 [11] due to the extremely low surviving population in the country. [12]
In recent years, the species has been found on Tasmania in Australia. It is the only Petalophyllum species on the island, [2] and in 2020 the Australian population's status was assessed as Threatened. [11]
The precise causes for the decline of Petalophyllum preissii are unknown, but invasive grasses like Festuca rubra may be forcing it out of some habitats. [10] Petalophyllum preissii is found on moist sandy ground alongside Riccia liverworts. [4]
The Marchantiophyta are a division of non-vascular land plants commonly referred to as hepatics or liverworts. Like mosses and hornworts, they have a gametophyte-dominant life cycle, in which cells of the plant carry only a single set of genetic information.
Metzgeriales is an order of liverworts. The group is sometimes called the simple thalloid liverworts: "thalloid" because the members lack structures resembling stems or leaves, and "simple" because their tissues are thin and relatively undifferentiated. All species in the order have a small gametophyte stage and a smaller, relatively short-lived, spore-bearing stage. Although these plants are almost entirely restricted to regions with high humidity or readily available moisture, the group as a whole is widely distributed, and occurs on every continent except Antarctica.
Jungermanniopsida is the largest of three classes within the division Marchantiophyta (liverworts).
Lepidoziaceae is a family of leafy liverworts. It is a group of small plants that are widely distributed.
Aneuraceae is a family of thallose liverworts in the order Metzgeriales. Most species are very small with narrow, branching thalli.
Schistochila vitreocincta is a species of liverwort in the family Schistochilaceae. Under its synonym Perssoniella vitreocincta it was the only species in the monotypic genus Perssoniella and family Perssoniellaceae. It is endemic to New Caledonia. Its natural habitat is subtropical or tropical dry forests.
Kymatocalyx rhizomaticus, synonym Stenorrhipis rhizomatica, is a species of liverwort in the Cephaloziellaceae family. According to the 2000 IUCN Red List, where it was assessed under the synonym Stenorrhipis rhizomatica, it is endemic to Sarawak. Other sources give its distribution as Central America and northern South America.
Herbertaceae is a family of liverworts. The family consists of the genera Herbertus, Schisma and Triandrophyllum. The genus HerpocladiumMitten, 1873 was later merged into the genus Herbertus.
Cryptothallus is a previously recognized genus of liverworts in the family Aneuraceae. The plants are small, and are white to pale green as a result of lacking chlorophyll. This feature led to the creation of a separate genus. The morphology of species assigned to Cryptothallus is very similar to that of Aneura. As a result, Karen Renzaglia in 1982 suggested that the only species then placed in the genus, Cryptothallus mirabilis, may be considered "merely as an achlorophyllous species of Aneura." Wickett and Goffinet argued the same position on the basis of sequences of nuclear, mitochondrial, and plastid DNA, and moved Cryptothallus mirabilis to Aneura. A 2010 molecular phylogenetic study confirmed the position of Cryptothallus within Aneura. This was accepted in the 2016 world checklist of hornworts and liverworts.
Phycolepidozia is a genus of liverwort in the family Cephaloziellaceae. It contains two species:
Solenostomataceae is a family of liverworts in the order Jungermanniales.
Acrobolbus epiphytus is a liverwort species in the genus Acrobolbus. It occurs in New Zealand.
Petalophyllum ralfsii, the petalwort, is a liverwort of the order Fossombroniales. It is a small green bryophyte that occurs in the Mediterranean region as far east as Turkey, and along the Atlantic coast of Europe as far as northwest Scotland. It grows primarily on moist sand dunes.
Cephaloziaceae is a family of liverworts.
Haplomitrium is a genus of liverworts.
Calypogeiaceae is a family of liverworts. This type of plant is a calcifuge.
Petalophyllum, or petalwort, is a genus of liverworts in the order Fossombroniales.
Petalophyllum americanum, common name petalwort, is a species of liverwort in the order Fossombroniales. It is endemic to the Gulf Coast of the United States in Arkansas, Louisiana, Mississippi, and Texas. It was first described as the European species Petalophyllum ralfsii in 1919, but a detailed study later showed that the North American form is a distinct species.
Cephaloziellaceae is a family of liverworts belonging to the order Jungermanniales.
John E. Braggins is a New Zealand botanist and bryologist, known for his research into ferns and liverworts. Braggins lectured at the University of Auckland from 1969 until 2000, during which time he supervised and mentored a significant number of New Zealand botanists. During Braggins' career, he has taken part in the identification of 12 species and one suborder, many of which are endemic New Zealand liverworts.
