Donatia novae-zelandiae | |
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Scientific classification | |
Kingdom: | Plantae |
Clade: | Tracheophytes |
Clade: | Angiosperms |
Clade: | Eudicots |
Clade: | Asterids |
Order: | Asterales |
Family: | Stylidiaceae |
Genus: | Donatia |
Species: | D. novae-zelandiae |
Binomial name | |
Donatia novae-zelandiae | |
Donatia novae-zelandiae is a species of mat-forming cushion plant, found only in New Zealand and Tasmania. [1] Common names can include New Zealand Cushion or Snow Cushion, [2] however Snow Cushion also refers to Iberis sempervirens . Donatia novae-zelandiae forms dense spirals of thick, leathery leaves, creating a hardy plant that typically exists in alpine and subalpine bioclimatic zones. [3] [4]
Donatia novae-zelandiae is one of two species in the genus Donatia, which is the only genus in the family Donatiaceae. [3]
The perennial plant forms a mat capable of reaching over a meter in diameter, made up of densely packed tufts tipped with imbricated spirals of leaves, all connected by one root system. [3] [5] [6] [7] Leaves are sessile, base widened, 5-6mm long and erect. Upper leaves are bright green, while lower leaves are brown, but still long persisting. In the leaf axils are 2-3mm long, tufts of dense white hairs. [3] [5] [6] [7] Stomata are apparent, running parallel along the main axis on both leaf surfaces, with their guard cells being surrounded by a distinctive circular ridge. [7] Flowers are white, 5-6mm wide, solitary and scattered across the surface of the mat. [5] [6] [7] Flowers feature 5 triangular sepals, 2 stamens and 5 pointed, oblong, 5mm long petals. [5] [6] Flowering occurs from January to March. [5] Fruit are turbinate shaped, with fruiting occurring from February to March. [5]
Classification of Donatia novae-zelandiae is somewhat controversial. [8] In 1908, Johannes Mildbraed described Donatiaceae as a subfamily of Stylidiaceae due to uncertainty if the two were significantly different. [9] Due to ecological, habitual and geographic similarities to Stylidiaceae, Donatiaceae was often not recognised as a family in many publications. [8] More recent studies find Donatiaceae to be sufficiently different from Stylidiaceae, based on unique anatomical, morphological, and embryological characteristics. [10] [8] These include an absence of floral column, free stamens and petals, smooth pollen and paracytic stomata. [8] [10] Donatiacae is therefore sister group to Stylidiaceae, with Donatiacae being considered an outgroup, sharing a common ancestor. [3] [8] [10] [11]
Although there is much merit for separate families, many classification systems still class Donatia within the Stylidiaceae family, such as APG III and the Dahlgren system. [12] The earlier APG II system did the same but allowed for optional recognition of Donatiacae. [12]
The species likely originated in Tasmania during the Pliocene and Pleistocene eras, when major Australian and New Zealand mountain ranges formed. This created subsequent glaciation and cooling temperatures, leading to the creation of modern alpine and sub-alpine environments. A long-distance dispersal event, likely aided by Antarctica brought Donatia novae-zelandiae, along with Stylidiaceae species to New Zealand, where they were pre-adapted for alpine and sub-alpine growth. [10]
Donatia novae-zelandiae is most prevalent in cushion moorland, which generally form in areas of high-rainfall with poor drainage, above 800m. The water logging, peat substrate and harsh conditions prevent trees from growing, so these areas become entirely dominated by cushion plants. Donatia novae-zelandiae can be found solitary, or in a mosaic of other cushions and micro shrubbery. [2]
The dense interlocking tufts of cushion plants allow them to survive harsh winds and resist freezing temperatures. In a mosaic, cushion plants are known to facilitate other species through this added protection. When tested on Donatia novae-zelandiae though, a 2012 study [13] by Brittany Cranston found that they were poor facilitators. When added to an open alpine area, species richness of the site was decreased. In contrast, another cushion species, Silene acaulis increased the species richness. It was also found that removing the neighbours of Donatia novae-zelandiae, resulted in notable heat stress. It was therefore concluded that there is great variation in the facilitative effects of cushion plants based on species. Donatia novae-zelandiae is seemingly more adapted to thrive in competition for moorland, gaining more benefit from its neighbours than it provides. It does not play the same role of growing on and stabilising skeletal substrates like other species do. [13]
Ecosystem engineering by cushion plants can also occur along natural waterways of moorland. Here, cushions can grow in height to create dam like walls that prevent water flow. The resulting effect is a series of stepped ponds of water, dammed by cushions such as Donatia novae-zelandiae, promoting further cushion growth in a positive feedback system. [2]
Donatia novae-zelandiae is currently classed as "Not Threatened" by the New Zealand Threat Classification System. [14] The narrow niche and clear threats do make them vulnerable in future. As a result of poor nutrient availability and growth focused on density, cushion plants grow slowly, making them vulnerable to disturbance. Trampling by humans has been recorded to cause significantly reduced coverage and lower species diversity than undisturbed areas. Degradation was more severe in water logged areas, creating greater threat to Donatia novae-zelandiae. [15]
Donatia novae-zelandiae is adapted to the cold. A 2015 study [16] showed that artificially warming a site by 1.8 degrees Celsius for two seasons resulted in decreased leaf length, leaf width, seed production and specific leaf area. [16] The most pronounced population decreases in Donatia novae-zelandiae have been a result of fire, of which the alpine species is rarely subjected to. When subject to fires, alpine moorland species take decades to regenerate if they do at all. [2] Climate change is therefore forecast to cause issues in both of these areas. [17]
Bolster heath or cushion moorland is a type of vegetation community that features a patchwork of very low growing, tightly packed plants found at the limits of some alpine environments. The cushion plants form a smooth surfaced 'cushions' from several different plants, hence the common name of cushion heath. The cushion growth habit provides protection against the desiccating wind and help keep the cluster warm.
The family Stylidiaceae is a taxon of dicotyledonous flowering plants. It consists of five genera with over 240 species, most of which are endemic to Australia and New Zealand. Members of Stylidiaceae are typically grass-like herbs or small shrubs and can be perennials or annuals. Most species are free standing or self-supporting, though a few can be climbing or scrambling.
Donatia is a genus of two cushion plant species in the family Stylidiaceae. The name commemorates Vitaliano Donati, an Italian botanist.
Forstera is a genus of small perennial plants in the Stylidiaceae family named in honour of the German naturalists Johann Reinhold Forster and his son, Georg Forster, who had previously described Forstera's sister genus, Phyllachne just five years earlier. It comprises five species that are endemic to New Zealand with the exception of F. bellidifolia, which is endemic to Tasmania. The species in this genus resemble those in a subgenus of the related genus Stylidium called Forsteropsis, but they are more closely related to the genus Phyllachne. Proposals to merge the two genera based on information from cladistic analysis have emerged because of these genera's morphological similarities and evidence that they are paraphyletic.
Forstera bellidifolia, the Tasmanian forstera, is a species in the family Stylidiaceae that is endemic to Tasmania, Australia. It was described by William Jackson Hooker in an 1851 volume of Icones Plantarum. It is notably different from other members of the genus in that it is not native to New Zealand nor does it possess the epigynous nectaries that are present in the other species.
A cushion plant is a compact, low-growing, mat-forming plant that is found in alpine, subalpine, arctic, or subarctic environments around the world. The term "cushion" is usually applied to woody plants that grow as spreading mats, are limited in height above the ground, have relatively large and deep tap roots, and have life histories adapted to slow growth in a nutrient-poor environment with delayed reproductivity and reproductive cycle adaptations. The plant form is an example of parallel or convergent evolution with species from many different plant families on different continents converging on the same evolutionary adaptations to endure the harsh environmental conditions.
Ewartia planchonii, commonly known as creeping cushionherb, is an endemic herb to alpine areas of Tasmania. E. planchonii is commonly found in the western highlands of Tasmania. The Ewartia genus is described as cushion plants/herbs due to the characteristic growth habits of low growing, highly compact mats which are made up of highly packed stems. These mats are slow-growing and are often located in soils that contain low nutrients.
Pterygopappus is a genus of flowering plants in the tribe Gnaphalieae within the family Asteraceae. There is only one known species, Pterygopappus lawrencii, which is endemic to alpine Tasmania. It forms thick, light blue/green mats with densely packed leaves. It is most common in the mountains of the northeastern part of the island. It is a slow grower and prefers cool, moist environments.
Dracophyllum milliganii is a species of angiosperm in the family Ericaceae and the sub-family Epacridoideae. It is a distinctive alpine shrub, endemic to western Tasmania.
Phyllachne colensoi, the yellow cushionplant, is a species of cushion plant in the Stylidiaceae family. It is native to both New Zealand and Tasmania, with colonisation of the latter being a somewhat recent dispersal. Phyllachne colensoi is frequently the dominant vegetation in upland bog habitats and is found throughout high mountain areas in New Zealand, but is only recorded from 12 sites in Tasmania in the west and south-west of the island.
Pomaderris paniculosa, commonly known as scurfy pomaderris, is a species of flowering plant in the family Rhamnaceae and is native to Australia and New Zealand. It is a shrub with hairy branchlets, round to elliptic or egg-shaped leaves with the narrower end towards the base and panicles of hairy, cream-coloured to greenish, sometimes crimson-tinged flowers.
Orites revolutus , also known as narrow-leaf orites, is a Tasmanian endemic plant species in the family Proteaceae. Scottish botanist Robert Brown formally described the species in Transactions of the Linnean Society of London in 1810 from a specimen collected at Lake St Clair. Abundant in alpine and subalpine heath, it is a small to medium shrub 0.5 to 1.5 m tall, with relatively small, blunt leaves with strongly revolute margins. The white flowers grow on terminal spikes during summer. Being proteaceaous, O. revolutus is likely to provide a substantial food source for nectivorous animal species within its range.
Tasmanian cushion plants are low growing, highly compact, woody, spreading mats that can grow up to 3 m in diameter, located mainly on the island of Tasmania. These mats are made up of tightly packed stems that grow at the same rate so that no apical rosettes protrude above the rest. The term cushion plant refers to a characteristic growth habit adopted by various species from a range of families to adapt to alpine and subalpine environments and areas of high latitude. They are adapted to grow in low nutrient areas and typically have deep taproots. Cushion plants are very slow growing and do not grow high above ground; mounds typically remain under 30 cm high. Underneath the living surface of the cushion, the plants either allow dead leaves to persist or produce non-photosynthetic material, resulting in an insulating effect.
Astelia alpina called pineapple grass, silver astelia, or perching lily is a commonly found species in alpine and subalpine areas of Tasmania and the Australian Alps. It is a perennial herb that typically dominates its environment by growing in dense clusters, called mats, in alpine bogs. There are two subspecies: Astelia alpina var. novae hollandiae from New South Wales and Victoria and Astelia alpina var. alpina endemic to Tasmania. Both subspecies appear very similar to each other. The species was originally described by Robert Brown.
Pimelea sericea is a species of flowering plant in the family Thymelaeaceae and is endemic to Tasmania. It is a shrub with densely hairy young stems, elliptic leaves arranged in opposite pairs, and compact clusters of white, pink or pinkish-white flowers.
Actinotus novae-zelandiae is a plant in the Apiaceae family, native to the South Island of New Zealand.
Helichrysum pumilum, commonly known as dwarf everlasting, is a rosette herb from the family Asteraceae. It is endemic to Tasmania, where it is commonly found in the West and Southwest of the island state. It is distinctive by its inflorescence, with the flower stalk being densely matted in fine white hairs and the daisy-like flower head having numerous pink or white ray floret-like bracts.
Abrotanella forsteroides, commonly known as the Tasmanian cushion plant, is an endemic angiosperm of Tasmania, Australia. The plant is a dicot species of the daisy family Asteraceae and can be identified by its bright green and compact cushion like appearance.
Dracophyllum minimum, commonly known as heath cushionplant or claspleaf heath, is a species of bolster cushion plant endemic to Tasmania, Australia. It is a low growing, highly compacted plant with white flowers, commonly found in alpine areas of the south, centre and west of Tasmania.
Sprengelia minima is a species of flowering plant of the family Ericaceae, and is endemic to Tasmania. It is a small shrub usually growing in alpine cushion plants and has many branches, overlapping, stem-clasping, sharply-pointed leaves, and white, tube-shaped flowers arranged singly on the ends of branches.