Casuarina
( kaz - yoo - uh - REE - nuh )
At-A-Glance InformationThis genus of fast-growing evergreen trees is commonly referred to as Beefwood, Native Pine, Australian Pine, or She-Oak, and needs full sun and little to regular water for best performance. These trees look a little like those in the Pinus genus; their jointed branches mimic the look of Pine needles, though their true leaves are inconspicuous. These trees can handle dry or wet soil, salinity, heat and wind, and are hardy down to a temperature of 15 degrees Fahrenheit. Fruits are similar to cones, and range in size from 1/4 inch to 1 inch long depending on the species grown. These trees are useful as shade trees, specimens or street trees, or as groundcovers. Take care when planting these trees in the landscape, as many species' pollen is a source of respiratory irritation and allergies.
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Casuarina Species and Varietals
Casuarina is the type genus in the plant family Casuarinaceae and includes 14 species. The genus name is derived from the Malay word for the Cassowary bird 'kasuari', referring to the similarities between foliage and the birds' feathers. She-Oak trees do best in zones 8, 9, 12-24, H1 and H2. To find your zone, click here: Zone Map.
Casuarina cristata (Belah, Muurrgu, Scaly-Barked Casuarina, Scrub She-Oak, Billa, Ngaree, Bulloak, Swamp Oak) Endemic to eastern Australia's inland regions, this species has fissured or scaly dark greyish-brown bark. Scale needles are dark green and trees typically reach between 33 and 66 feet tall at maturity. |
Casuarina cunninghamiana (River She-Oak, Creek Oak, River Sheoak) This species is the tallest and overall largest species in the genus, and reaches 70 feet tall and 30 feet wide. Branches are dark green, and the tree has a fine texture. Creek Oak is native to Australia and New Guinea, and the species is named for English botanist and plant collector Allan Cunningham. |
Casuarina equisetifolia (Horse-Tail Tree, Coastal She-Oak, Iron Wood, Beach Casuarina, Whistling Tree) This species reaches 40-60 feet tall and 20 feet wide with a fast growth rate. It has greyish green, pendulous branches. These trees are native to India, Australia, New Guinea, and Southeast Asia. Bark is scaly to furrowed. |
Casuarina glauca (Swamp She-Oak, Swamp Buloke, Marsh Sheoak, Grey She-Oak, Native Pine, Guman) Endemic to eastern Australia, this species has fissured, scaly greyish brown bark and often forms root suckers. This species is used as a street tree, windbreak, and harvested for timber in its native range. Roots will invade underground water and sewage pipes within 50 feet of the base of the tree. Variety 'Cousin It' (also called 'Kattang Karpet', pictured) is a prostrate form of the species, and is widely cultivated as a groundcover plant in gardens. |
Casuarina obesa (Swamp She-Oak, Swamp Oak, Western Swamp Oak, Goolee, Kweela, Kwerl, Quilinock) These trees are endemic to southern continental Australia, and forms a small tree or shrubby plant. This species suckers freely, and has drooping to spreading branches. Western Swamp Oak reaches 10-50 feet tall when mature. |
Caring for and pruning casuarina Trees
Casuarina trees should be planted in full sunlight, requiring at least 6-8 hours of sun each day. The ideal soil for these trees is variable, they can do well in sandy, loamy and even poor soils. They do prefer soil to be well-draining, and can tolerate slightly acidic to alkaline pH. These trees are tolerant of salty soils and coastal conditions, making them ideal for planting in areas with salt spray or poor soil quality. Water newly planted trees regularly to help them establish a good root system. Mature trees are drought-tolerant, and can get by with only occasional deep waterings in the driest times of the year. Casuarina can tolerate cold temperatures down to 20 degrees Fahrenheit, and then will need some protection to avoid damage. They do not need to be fertilized, and have the ability to fix nitrogen in soil, making them great candidates for rehabilitating poor soils. These trees also require very little pruning, and can reach their full height potential in as little as 10 years. If these trees are being used as a windbreak, lower branches should be kept on the tree to keep it dense.
Propagation
Casuarina can be propagated either by using cuttings or from seed. To ensure that your propagated plant will have the exact same qualities and characteristics as the parent plant, use the cutting method. If you would like to experiment and see what plant you can grow from seed, just keep in mind that it will not necessarily be the same as the parent plant. To propagate your tree, follow the instructions below:
Propagating Casuarina by Cutting
Propagating Casuarina by Seed
Propagating Casuarina by Cutting
- Gather your materials. You'll need a clean, sanitized, sharp pair of garden shears, rooting hormone, a pencil, and a 3-inch pot filled with well-draining compost or other organic material. If you don't have any potting medium on hand, you can make some. Just mix together equal parts (by volume) moss peat and horticultural-grade sand or grit sand.
- In spring or early summertime, choose the plant that you'd like to propagate. Ensure that this plant has had a good watering the night before, as this will improve the chances your cutting will take root. Cut one or more 6 inch portion(s) of the end of a non-blooming branch and strip the leaves off of the lower half. Make a hole in your planting medium by pushing your pencil into the soil. Dip the end of the stem in rooting hormone, and plant it in your pot. Fill in soil around the cutting to support it, but do not pack it down too much.
- Moisten with water, and ensure that the pot has good drainage. Your pot should be kept in warm, sunny conditions indoors (and not in direct sunlight). Water whenever your soil is dry under the top layer. After about four to six weeks have passed, your cutting should be rooted. When you notice new growth, you'll know you have roots.
- Keep your new plant in an area with bright light (though not direct sunlight) and temperatures between 55 and 70 degrees Fahrenheit. Ensure that the soil stays moist, but not wet, until the next spring, when you can transplant it to its new home. Ensure that the last frost of the year has occurred before doing this, as it can seriously damage your new shrub.
Propagating Casuarina by Seed
- Keep in mind that the plant you get from seed will not necessarily mimic all of the characteristics of the parent plant. To propagate by seed, you will need a paper bag, a pot or tray filled with well-draining compost or other organic material, a spray bottle and a fork. If you don't have any potting medium on hand, you can make some. Just mix together equal parts (by volume) moss peat and horticultural-grade sand or grit sand. You will also, after a few weeks, need individual 3-inch pots for each seedling that grows.
- Harvest your seeds. The seeds for these trees are contained inside of the small female cones produced by trees and ready for harvesting in summertime. Cones will begin to fall from the tree, and can be picked off the ground before they fully open and release all seeds inside. Place cones in a paper bag while collecting, and then leave the bag in a cool, dark, dry place as they continue to release their seeds. After a few days or so, shake the bag, and then pour out the contents and separate out the seeds.
- Water your prepared seed tray or pot filled with soil, and ensure that good drainage is occurring. Place your seeds in your prepared pot or seed tray about a quarter inch to a half-inch under the soil surface. Cover them with soil and water with your spray bottle. Place your tray of seeds in a warm area that receives bright, indirect light. A greenhouse is the most ideal climate, but a planting tray inside a window will do as well. Germination usually takes about 14 days from sowing. Once you begin to see seedlings sprout and they are able to be handled, transplant them to their own individual 3-inch pots, filled with the same potting medium as described in Step 1. Loosen the seedlings from the potting medium by digging down with the tines of your fork about an inch and a half, gently working the seedling up until it is out. Then, replant the seedling in its individual pot.
- Keep the seedling's potting medium moist, but not wet, by spraying the soil with your spray bottle. Keep your new plant in an area with bright light (though not direct sunlight) and temperatures between 55 and 70 degrees Fahrenheit. Ensure that the soil stays moist, but not wet, until the next spring (after the danger of frost has passed), when you can transplant it to its new home.
Problems and Pests
Casuarina trees are relatively pest and disease tolerant, buy they can be affected by the following:
- Crickets and Grasshoppers
- Stem Borers
- Mushroom Root Rot
- Armored Scales
- Cottony Cushion Scale
- Armillaria Root Rot
- Heart Rots and Wood Decay
Gallery
These trees can be trimmed into many different shapes, including topiary.
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Casuarina glauca is commonly used as a mounding groundcover plant, and is a beautiful addition to water-wise and coastal gardens.
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These trees are frequently used as windbreak plantings, to protect gathering spaces and agricultural land.
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The flowers on Casuarina trees are red and look a little like a mini-bottlebrush flower.
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These trees are used to regenerate landscapes, due to their ability to fix nitrogen and deal with poor soil quality.
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Casuarinas are common shade trees in coastal regions, and can grow well in salty spray conditions.
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Videos
Get all of your Casuarina questions answered.
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Learn about these interesting trees.
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How to grow Casuarina from seed.
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How to create a bonsai from a young Casuarina tree.
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Resources
The New Sunset Western Garden Book: The Ultimate Gardening Guide (2012) - Page 225, Casuarina
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