CASUARINA: CHARACTERISTICS, HABITAT, CULTIVATION, USES, SPECIES - BIOLOGY - 2025

The genus Casuarina is a group of evergreen trees or shrubs similar to conifers that, however, belong to the family Casuarinaceae. Native to the islands of the Pacific and southeastern Australia, they are very common in subtropical, tropical and temperate regions around the world.

They are plants that reach up to 30 m in height, with an erect trunk and rapid growth with the bark split as it develops. Its acicular, thin, elongated and pendulous leaves are light green or deep green, depending on the species.

Casuarina. Source: Adityamadhav83

Most are perennial species for ornamental and forest use, highly appreciated for their easy adaptation to different soils and climates. They become accustomed to saline soils and withstand low rainfall well, even thriving in coastal environments withstanding strong winds.

The genus Casuarina is made up of approximately fifty species of various sizes and morphological characteristics. Some of the best known are Casuarina cristata, Casuarina cunninghamiana, Casuarina equisetifolia and Casuarina glauca.

General characteristics

Root

Its root system is deep pivoting with an extensive secondary root system. In fact, it has numerous laterally extended rootlets at the surface level that gives it firm support.

Trunk

Evergreen and evergreen trees are made up of a straight and thick trunk, sometimes branched, with cracked bark and brown or greyish in color. Generally reaches more than 20-30 m in height, with thin branches and needles similar to pine trees, thin, green and articulated

Leaves

The leaves are made up of small scales arranged in foliar whorls from the joints. Its foliage, pyramidal in shape with fine leaves, resembles conifers, but they differ in that their needles are divided into septa.

Detail of the septate needles. Source: John Tann from Sydney, Australia

Inflorescences

The most common species are monoecious with female and male flowers on the same plant, but there are also dioecious species. The robust-looking 2-3 mm female inflorescences turn into a 6-15 mm spherical pineapple when fruiting.

The 2-4 cm male inflorescences are formed by hanging spikes or brown catkins with green twigs at their ends. Pollination is generally anemophilic and occurs with the intervention of the wind.

Fruit

The fruit is a woody-looking fruit of 1.5-2 cm in diameter formed by several fruits of just 3 mm. Initially they are gray-greenish in color and then turn reddish-brown when ripe, when they open, they release the winged seeds or samaras that the wind disperses.

Taxonomy

- Kingdom: Plantae.

- Division: Magnoliophyta.

- Class: Magnoliopsida.

- Order: Fagales.

- Family: Casuarinaceae.

- Genus: Casuarina L.

Etymology

The name of the genus comes from the Malay "kasuari" which means cassowary, alluding to the similarity of its foliage with the feathers of this bird native to Australia and New Guinea.

Detail of the fruitlessness. Source: John Tann from Sydney, Australia

Habitat and distribution

In its natural habitat it is located on sandy soils of low salinity, clay-silty soils of medium fertility or on soils of limestone origin. The Casuarina is a genus that has a wide adaptation to various types of terrain, being little tolerant to flooded lands.

Likewise, it adapts to a wide pH range (ranging from 5.0 to 9.5) and to terrains with deep water tables. In fact, it grows and develops effectively on loose, porous soils with good drainage.

In general, they are species that live in symbiosis with soil microorganisms. Therefore, nutritional deficiencies that inhibit the development of mycorrhiza or soil microbiota will influence the nutritional quality of the plant.

These species are associated with low growth vegetation such as grasses or herbs, as well as understory and open forests. In addition, its litter is of low decomposition and contributes certain toxicity to the land, preventing the development of other plants around it.

Native to Australia it is distributed by Queensland, New South Wales, Victoria, South Australia and Western Australia. As well as in Malaysia and certain islands in the South Pacific (Polynesia, New Zealand, New Guinea or Samoa).

Culture

Casuarina are species typical of warm environments that have a certain tolerance to occasional cold and little rainfall. They are typical plants of coastal regions that develop under full sun exposure and are not very susceptible to salinity.

They are successfully grown in coastal areas on sandy soils where their strong root system contributes to soil stability. Likewise, they are species used for the reforestation of intervened land or as windbreaks in crop fields.

Spread

The propagation of Casuarina can be done by means of seeds or by vegetative multiplication through cuttings. The use of viable seeds is essential to obtain healthy plants. However, this technique is slow to obtain productive plants.

Propagation by cuttings is ideal to achieve robust plants with similar characteristics to the mother plant in less time. Cuttings are selected during the summer from semi-woody branches free from physical damage, pests or diseases.

Casuarina Forest. Source: pixabay.com

With the use of a sharp knife, an oblique cut is made at the end to be rooted. This type of cut allows to obtain a greater rooting surface and avoids the accumulation of water on the cut area.

The cuttings, 20-25 cm long, are placed in a substrate in equal parts of peat and seedling sand. The containers are placed under greenhouse conditions maintaining continuous irrigation and constant humidity until the beginning of rooting.

In this way, the cuttings emit the first shoots after 30-45 days, which indicates that roots have formed. When the new seedlings have acquired sufficient robustness, they are transplanted into semi-shaded polyethylene bags until they are sown in the final field.

Transplant

During the first phase of growth, the Casuarina requires soils with a high content of organic matter and sand that facilitate drainage. It is recommended to transplant at the end of winter, in order to maintain the nursery conditions and ensure that the following year it is ready to transplant on firm ground.

Irrigation

The Casuarina is a plant that resists the lack of humidity, but during its growth phase it requires watering in the summer-spring seasons. However, during autumn-winter the waterings should be sporadic unless the plant has marked deficiencies.

Fertilization

During spring and summer it is advisable to apply an average monthly dose of liquid fertilizer with the irrigation water. This fertilizer must contain all the necessary elements for the proper growth and development of the plant, from macroelements to microelements.

Pruning

Generally, the Casuarina does not require pruning during the growth phase. Only during the winter outing is it recommended to remove damaged or dry branches to prevent the incidence of pests or fungal diseases.

Plagues and diseases

Most of these species are resistant to attack by pests and diseases. However, certain larvae of Lepidoptera of the Hepialidae family use Casuarina as a food source without causing economic damage.

Casuarina seeds. Source: Philmarin

Applications

Ornamental

Due to their rapid growth and similarity to conifers, casuarinas are used as ornamental plants in parks and gardens. However, due to its large size, its planting should be limited only in open spaces.

Wood

The strong and firm wood of Cauarina is used in the lumber industry for the manufacture of fences, fences and plates. In turn, wood has a high degree of ignition, which is why it is highly valued for obtaining charcoal.

Medicinal

Most Casuarina species contain tannins as active components that are used for medicinal purposes. In fact, infusions of the bark are used as astringents or to alleviate discomforts related to gastroenteritis.

Protection

In some coastal towns, casuarinas are used as windbreaks in order to avoid the action of strong winds. In fact, the presence of double rows is common along trails and roads.

Representative species

Casuarina equisetifolia

Known as Philippine agoho, sadness tree, horsetail casuarina, or Australian pine, it is a semi-evergreen species native to tropical coasts. Native to Australia and Southeast Asia in Malaysia and Polynesia, it is commonly used as a forester or windbreaker.

Casuarina equisetifolia. Source: Forest & Kim Starr

This tree can reach 25-30 m in height and has a very cracked bark in longitudinal bands. It is a species used to reforest urban spaces due to its rapid growth and its ability to fix nitrogen in symbiosis with soil mycorrhizae.

Casuarina cristata

Tree 10-20 m tall and 1 m in diameter with hanging branches and small scale-shaped leaves. Known as bela and Australian belah it is native to Australia, from New South Wales to southern Queensland.

Casuarina cristata. Source: Mark Marathon

It is a species that adapts to sandy, loamy or clay soils, but well drained as it does not tolerate waterlogging. It generally grows in sclerophyllous forests and open forests, but is also found in scrublands and dry forests.

Casuarina glauca

Known as swamp oak, it is a native species of the littoral regions of South Australia, Western Australia, New South Wales, Queensland and Victoria. It is a tree with hanging branches, a straight stem and a slightly ribbed grayish or brown bark, which reaches 15-25 m in height.

Casuarina glauca. Source: Forest & Kim Starr

Its wood is heavy and hard, of a reddish-brown color difficult to saw, being used for making furniture and carpentry in general. It is a species used in reforestation as it protects very sandy soils and slopes in danger of wind erosion.

Obese casuarina

The swamp oak or marsh oak is a 15 m tall evergreen tree branching from the base. Highly tolerant to salinity and damp soils, it can be used to reforest saline and seasonally flooded soils.

Infrutescence of Obese Casuarina. Kevin Thiele from Perth, Australia

It is a moderate to fast growing perennial tree that can be used as a windbreak for control of wind erosion. Native to Western Australia, its natural habitat is located along the Murchison River to the south through the Coastal Plain and the Robinson Ranges.

Casuarina teres

A medium-height species endemic to northwestern New Caledonia, between the Pouembout and Voh regions, which is in danger of extinction. It is located on the coastal maquis and degraded or intervened environments at an altitude of 30 to 200 meters above sea level.

Characteristic trunk of Casuarina. John Tann from Sydney, Australia

The great mining activity in the Koniambo mines has indirectly affected the survival of this species. However, its main threat is related to the degradation of its natural environment caused by forest fires.

References

1. Casuarina. (2017). Wikipedia, The Free Encyclopedia. Recovered at: es.wikipedia.org
2. Casuarina. (2018) Elicriso: Magazine about the environment and nature. Recovered in: elicriso.it
3. Casuarina (2018) Botanical Consultation Guide II. Faculty of Exact and Natural Sciences and Surveying (UNNE).
4. Rojas-Rodríguez, F. and Torres-Córdoba, G. (2013) Casuarina. Mesoamerican Kurú Forestry Magazine (Costa Rica) Volume 10, No. 25, ISSN: 2215-2504.
5. Sánchez de Lorenzo-Cáceres, JM (2014) Casuarina. Ornamental Trees. Spanish Ornamental Flora.
6. Vibrans Heike (2009) Casuarinaceae. Casuarina equisetifolia L. Casuarina. Mexican weeds. Recovered at: conabio.gob.mx