In botany , an evergreen is a plant which has foliage that remains green and functional throughout the year. This contrasts with deciduous plants, which lose their foliage completely during the winter or dry season. Consisting of many different species, the unique feature of evergreen plants lends itself to various environments and purposes.
22-630: Metrosideros excelsa , commonly known as the pōhutukawa , New Zealand Christmas tree , or iron tree , is a coastal evergreen tree in the myrtle family, Myrtaceae , that produces a brilliant display of red (or occasionally orange, yellow or white) flowers, each consisting of a mass of stamens . The pōhutukawa is one of twelve Metrosideros species endemic to New Zealand. Renowned for its vibrant colour and its ability to survive even perched on rocky, precarious cliffs, it has found an important place in New Zealand culture for its strength and beauty, and
44-463: A coastal shrub with white berries, Sophora tomentosa . The -hutu- part of the word comes from * futu , the Polynesian name for the fish-poison tree ( Barringtonia asiatica ; compare with Fijian : vutu and Tongan : futu ), which has flowers similar to those of the pōhutukawa. Pōhutukawa grow up to 25 metres (82 ft) high, with a spreading, dome-like form. They usually grow as
66-497: A cold or dry/wet season. Evergreen trees also lose leaves, but each tree loses its leaves gradually and not all at once. Most tropical rainforest plants are considered to be evergreens, replacing their leaves gradually throughout the year as the leaves age and fall, whereas species growing in seasonally arid climates may be either evergreen or deciduous. Most warm temperate climate plants are also evergreen. In cool temperate climates, fewer plants are evergreen. In such climates, there
88-652: A height of 20 metres and a spread of 38 metres (125 ft). A pōhutukawa tree with an estimated age of 180 years known as 'Te Hā' is fully established at an Auckland City park. 'Te Hā' is the largest urban specimen in the country. Plans to build a monument in honour of victims of the Erebus Disaster in proximity to the tree activated significant local opposition in 2021. Evergreen There are many different kinds of evergreen plants, including trees , shrubs , and vines. Evergreens include: The Latin binomial term sempervirens , meaning "always green", refers to
110-731: A higher soil acidity and lower soil nitrogen content. This is the case with Mediterranean evergreen seedlings, which have unique C and N storages that allow stored resources to determine fast growth within the species, limiting competition and bolstering survival. These conditions favor the growth of more evergreens and make it more difficult for deciduous plants to persist. In addition, the shelter provided by existing evergreen plants can make it easier for younger evergreen plants to survive cold and/or drought. Evergreen plants can have decorative as well as functional uses. In months where most other plants are dormant, evergreens with their sturdy structure, and vibrant foliage are popular choices to beautify
132-544: A landscape. Additionally, evergreens can serve as a windbreak , stopping heat loss from buildings during cold months when placed on the northwest side of a structure. Traditional M%C4%81ori healing Rongoā (or Rongoā Māori ) refers to the traditional Māori medicinal practices in New Zealand. Rongoā was one of the Māori cultural practices targeted by the Tohunga Suppression Act 1907 , until lifted by
154-420: A larger volume of parenchyma and air spaces per unit leaf area. They have larger leaf biomass per unit leaf area, and hence a lower specific leaf area . Construction costs do not differ between the groups. Evergreens have generally a larger fraction of total plant biomass present as leaves (LMF), but they often have a lower rate of photosynthesis. Deciduous trees shed their leaves usually as an adaptation to
176-431: A multi-trunked spreading tree. Their trunks and branches are sometimes festooned with matted, fibrous aerial roots . The oblong, leathery leaves are covered in dense white hairs underneath. The tree flowers from November to January with a peak in early summer (mid to late December), with brilliant crimson flowers covering the tree, hence the nickname New Zealand Christmas tree. There is variation between individual trees in
198-438: Is a predominance of conifers because few evergreen broadleaf plants can tolerate severe cold below about −26 °C (−15 °F). In addition, evergreen foliage experiences significant leaf damage in these cold, dry climates. Root systems are the most vulnerable aspect of many plants. Even though roots are insulated by soil, which tends to be warmer than average air temperatures, soil temperatures that drop too low can kill
220-543: Is regarded as a chiefly tree ( rākau rangatira ) by Māori . The generic name Metrosideros derives from the Ancient Greek mētra or " heartwood " and sideron or "iron". The species name excelsa is from Latin excelsus , "highest, sublime". Pōhutukawa is a Māori word . Its closest equivalent in other Polynesian languages is the Cook Island Māori word po'utukava , referring to
242-495: Is renowned as a cliff-dweller, able to maintain a hold in precarious, near-vertical situations. Like its Hawaiian relative the ʻōhiʻa lehua ( M. polymorpha ), the pōhutukawa has been shown to be efficient in the colonisation of lava plains – notably on Rangitoto , a volcanic island in the Hauraki Gulf. In New Zealand, pōhutukawa are under threat from browsing by the introduced common brushtail possum which strips
SECTION 10
#1732876095410264-506: The Maori Welfare Act 1962 . In the later part of the 20th century there was renewed interest in Rongoā as part of a broader Māori renaissance . Rongoā can involve spiritual, herbal and physical components. Herbal aspects used plants such as harakeke , kawakawa , rātā , koromiko , kōwhai , kūmarahou , mānuka , tētēaweka and rimu . The practice of Rongoā is only regulated by
286-572: The North Island of New Zealand, north of a line stretching from New Plymouth (39° S) to Gisborne (38° S), where it once formed a continuous coastal fringe. By the 1990s, pastoral farming and introduced pests had reduced pōhutukawa forests by over 90%. It also occurs naturally on the shores of lakes in the Rotorua area and in Abel Tasman National Park at the top of South Island. The tree
308-777: The Wellington area and in the north of the South Island . It has also naturalised on Norfolk Island to the north. Pōhutukawa have been introduced to other countries with mild-to-warm climates, including south-eastern Australia, where it is naturalising on coastal cliffs near Sydney . In coastal California , it is a popular street and lawn tree, but has caused concern in San Francisco where its root systems are blamed for destroying sewer lines and sidewalks. In parts of South Africa , pōhutukawa grow so well that they are regarded as an invasive species . The Spanish city of A Coruña has adopted
330-476: The area in which they reside. The excellent water economy within the evergreen species is due to high abundance when compared to deciduous species. Whereas deciduous trees lose nutrients whenever they lose their leaves. In warmer areas, species such as some pines and cypresses grow on poor soils and disturbed ground. In Rhododendron , a genus with many broadleaf evergreens, several species grow in mature forests but are usually found on highly acidic soil where
352-546: The evergreen nature of the plant, for instance: The longevity of individual leaves in evergreen plants varies from a few months to several decades (over 30 years in the Great Basin bristlecone pine ). Japanese umbrella pine is unique in that it has its own family of which it is the only species. Evergreen and deciduous species vary in a range of morphological and physiological characters. Generally, broad-leaved evergreen species have thicker leaves than deciduous species, with
374-423: The nutrients are less available to plants. In taiga or boreal forests , it is too cold for the organic matter in the soil to decay rapidly, so the nutrients in the soil are less easily available to plants, thus favoring evergreens. In temperate climates, evergreens can reinforce their own survival; evergreen leaf and needle litter has a higher carbon-nitrogen ratio than deciduous leaf litter , contributing to
396-448: The plant. The exact temperature which evergreen roots can handle depends on the species, for example, Picea Glauca (White Spruce) roots are killed at −10 °F (−23 °C). In areas where there is a reason for being deciduous, e.g. a cold season or dry season, evergreen plants are usually an adaptation of low nutrient levels. Additionally, they usually have hard leaves and have an excellent water economy due to scarce resources in
418-469: The pōhutukawa as a floral emblem. At least 39 cultivars of pōhutukawa have been released. Duncan & Davies nurseries were a leading force in the mid-20th century, while the late Graeme Platt has been responsible for 16 different cultivars so far, including a rare white-flowering tree. Cultivars include: A giant pōhutukawa at Te Araroa on the East Coast is reputed to be the largest in the country, with
440-505: The timing of flowering, and in the shade and brightness of the flowers. In isolated populations genetic drift has resulted in local variation: many of the trees growing around the Rotorua lakes produce pink-shaded flowers, and the yellow-flowered cultivar 'Aurea' descends from a pair discovered in 1940 on Mōtītī Island in the Bay of Plenty . The pōhutukawa's natural range is the coastal regions of
462-435: The tree of its leaves. A charitable conservation trust, Project Crimson , has the aim of reversing the decline of the pōhutukawa and other Metrosideros species – its mission statement is "to enable pōhutukawa and rata to flourish again in their natural habitat as icons in the hearts and minds of all New Zealanders". Pōhutukawa wood is dense, strong and highly figured. Māori used it for beaters and other small, heavy items. It
SECTION 20
#1732876095410484-417: Was frequently used in shipbuilding, since the naturally curvy shapes made strong knees . Extracts are used in traditional Māori healing for the treatment of diarrhoea, dysentery, sore throat and wounds. Pōhutukawa are popular in cultivation, and there are fine examples in most North Island coastal cities. Vigorous and easy to grow, the tree flourishes well south of its natural range, and has naturalised in
#409590