Page 56 - BSAM 2015 Q1

SPECIES GUIDE: Casuarina Equisetifolia By Archana Gupta, Sujata Bhat, Nikunj Parekh and Jyoti Parekh, India
Common Names:
casuarina
coast sheoak
coast she oak coastal she-oak) beach casuarina beach oak
beach sheoak beach she-oak whistling tree horsetail she oak horsetail beefwood horsetail tree Australian pine ironwood whistling pine Filao tree
agoho
The first finer needle Casuarina came to India some two decades back as a gift from none other than our friend from Indonesia, Budi Sulistyo, which is of historical importance. Large numbers of the fine needle Casuarina that are now seen in India are nursery grown and not yamadori. These were then made affordable and reached all nooks and corners of peninsular coastal India.
Casuarina is a genus of shrubs and trees in the fam- ily Casuarinaceae, growing in sub-tropical and tropical coastlines of Australia and islands of the Pacific, and widely spread to Hawaii, Florida, India, Indonesia, Ma- laysia, Thailand, Africa, Egypt, some part of China and Japan, Caribbean islands etc. Commonly known as She- oak or Australian pine because the branches and scale- like “needle” leaves bear a superficial resemblance to the pines. In India it is commonly called Jungli saru, Jungli Zhao or Vilayati saru. The Indian Casuarina has coarser, thicker and longer branches with darker green color as compared with the Indonesian variety.
Casuarina grows in subtropical and tropical, both at the seashore in dry, salty, calcareous soils and up in the mountains in high rainfall area on volcanic soils. Although considered as invasive species in many coun- tries, some are introduced and planted as windbreaks in windswept areas.
Plant Description:
Casuarinas are large deciduous trees reaching heights of up to 35 meters with finely branched crowns that flatten with age. The trunk is often straight; cylindri- cal in diameter measuring 100–150 cm. Branches are drooping, needle-like, and gray-green in color. The highly reduced tooth-like leaves are in whorls of seven to eight per node.
Flowers are unisexual with two bracteoles. Male flow- ers occur as terminal, simple elongated spikes borne in whorls with a single stamen. Female flowers are borne on short, lateral branchlets and are cylindrical or cone- shaped. Casuarina trees are either monoecious or di- oecious. Casuarina equisetifolia is monoecious which means that they bear both the male and female flowers on the same plant.
The fruit is a woody, oval structure superficially resembling a conifer cone made up of numerous car- pels each containing a single seed with a small wing called Samara. The generic name is derived from the Malay word for the cassowary or kasuari, alluding to the similarities between the bird’s feathers and the plant’s foliage.
Casuarinas are found in semi-arid and sub-humid climates. It is the only wooded tree that grows over a ground cover of dune grasses and salt-tolerant broad- leaved herbs. This is one reason an occasional saltwater
spray is good for the bonsai plant or a potted tree. Casu- arina can bear temperatures of 10–35 °C, annual rainfall of 200–500 mm. It tolerates slightly alkaline and calcar- eous soil but is intolerant to prolonged water logging.
Casuarina as a Bonsai
Casuarina was first introduced as bonsai in Indonesia where Casuarina equisetifolia mostly grows along the coastline of this island. Excessive pruning and cutting of these trees resulted in stunted trees that attracted bonsai enthusiasts who started collecting them as bonsai mate- rial. Pruning techniques of the foliage were developed which made the Casuarina resemble pines. Casuarinas are amenable to all styles of bonsai either as individual trees or in groups.
Propagation
Casuarina can be easily propagated by seed, stem cut- ting and air layering. The success rate of stem cutting and air layering is quite high and rapid.
When collected from the wild as yamadori, the trees can be extremely sensitive due to drastic disturbance of the root system. It is then advisable to cut a minimum portion of the root ball and treat the roots with a hor- mone solution that will help revive the tree in the pot. It is also advisable to keep the original soil as much as pos- sible. After potting, keep the plant in a shady place until the plant revives and new sprouts develop before moving it out under the full sun. Care should be taken to ensure that the potted plant should not be over watered, but misting of the tree to keep up humidity levels is advisable.
Casuarina equisetifolia grows along the sandy coast- line with strong winds and sunlight, the same climatic and soil conditions are applicable for bonsai as well. Shady conditions will cause slow growing; the branches are weak and droopy and unhealthy. The soil should be highly porous to allow for good drainage. We use about 60–70% sand and the rest humus as potting medium. Porous structure of the soil is extremely important for the root hairs to develop. The sandy soil with humus ensures that the soil retains its moisture content. Indo- nesian bonsai experts recommend soil that is acquired from volcanic mountains which is porous. In India, we have experimented by breaking and crushing burnt coke, which has a granular structure and helps provide good drainage.
Styling and Pruning Techniques.
When a Casuarina tree is first styled, it is advisable to cut back all the branches to the level of the trunk. This is preferably done during the growing season. When cut back, the trunk develops a mass of branches so that new branches can be selected at appropriate points on the trunk and developed further for a complete re-style
54 | BCI | April/May/June 2015