Sterculia URENS

Sterculia URENS - Gum karaya, Ghost tree, Sterculia urens.

Can be grown in bonsai style!

Sterculia is related to Firmiana, a genus of flowering plants in the subfamily Sterculioideae of the Malvaceae family, formerly placed in the family Sterculiaceae. The genus Firmiana, named in the 18th century after Count Karl Joseph von Firmian, grows natively in the subtropics of southern Japan, Indochina, and China in the wild. Cultivated in Crimea, the Krasnodar Krai, Abkhazia, Uzbekistan, Tajikistan, and Turkmenistan as an ornamental plant, mature trees can withstand frost down to -20 °C (-4 °F).

In Asia, Firmiana serves as a timber source for high-grade paper production and bark for cordage. In China, the seeds are used to prepare a coffee-like beverage due to their caffeine content. The leaves possess medicinal properties and are used worldwide as a stimulating and tonifying agent for fatigue, asthenic conditions, and hypotension.

Sterculia urens is a deciduous, fast-growing tree with a rounded or umbrella-shaped crown, reaching 9-12 m (30-39 ft) in height. The straight, smooth trunk is covered with gray-green bark. Bright green, 3-5-lobed large leaves, turning yellow in autumn, outwardly resemble maple leaves.

It first blooms in July at the age of 6-8 years with unisexual lemon-yellow flowers gathered in panicles up to 25 cm (10 in) long. After flowering, fruits appear in September-October as leathery five-part follicles 3-10 cm (1.2-3.9 in) long, containing grayish-yellow spherical edible seeds about 1 cm (0.4 in) in diameter.

Seeds are stratified for 2 months in a cold environment at a temperature of 4-5 °C (39-41 °F). Under home conditions, seeds are placed in the refrigerator. Prior to planting, seeds are soaked in hot water for 12-24 hours, then sown to a depth of 2-4 cm (0.8-1.6 in) and covered with a layer of soil. They are moistened with a spray bottle, covered with film, and germinated in the light at a temperature of 21-22 °C (70-72 °F). Seedlings require ventilation. It is essential to avoid both waterlogging and desiccation of the sowings.

Seeds may require peeling one or two outer layers down to the glossy black seed (see photo 4).

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Sterculia is easy to grow. It is undemanding regarding soils: it grows well in sandy grounds, and at the same time, on the Black Sea coast of the Caucasus, thrives on alluvial impermeable soils. Due to its distinctive crown, it casts dense shade and is used in ornamental street plantings.