Common name: Hollock

Hollock is a timber and landscape tree native to India and Southeast Asia, its natural range extending from the Himalayan foothills east to Myanmar (Burma), Thailand, Malaysia, Indonesia and southern China.

Exceptional specimens in natural forests may attain up to 40 m (130 ft) but are typically 15 to 25 m (50 to 82 ft) tall on open sites. The trunk is usually straight and on older trees buttressed, supporting a wide-branching crown made up of long, slender, gently dropping branches. The bark is grey and smooth, with age becoming flaking.

The leaves are elliptical, 10 to 20 cm (4 to 8 in) long, dull green, and finely toothed on the margins. They are arranged in pairs along the branches and remain on the tree in all seasons, though some leaf fall occurs in the drier parts of its range. 

The flowers are small with light yellow petals, held tightly packed in long, slender clusters at the ends of the branches. They bloom from summer to autumn, coinciding with the rainy season in its native range, and are followed by clusters of small, green, winged seedpods, becoming bright pink when mature.

Use

Hollock is cultivated as an ornamental for its showy pink seedpods and weeping form, which are on best display in large gardens and parks, where the tree has room to grow. It is also cultivated to shade Cardamom (Elettaria cardamomum) plants in upland plantations.

It produces a medium-weight wood with pale brown heartwood, averaging about 500 to 700 kgs per cubic meter (31 to 44 lbs per cubic ft), with low natural resistance to rot and decay. This puts it in the non-durable hardwood class, making it fit only for indoor use. Large, well-formed logs are sawn into planks used chiefly for making fine furniture and cabinets. Small diameter logs and branchwood are a valued source-wood for making charcoal.

Climate

Grows naturally in humid subtropical and tropical mid- to high-elevation climates, generally areas with annual lows of 12 to 20°C, annual highs of 21 to 32°C, annual rainfall of 1500 to 5500 mm and a dry season of 5 months or less. Although it will also grow in low rainfall areas with a dry season of up to 8 months, its growth is usually stunted under such conditions.

Growing

New plants are usually grown using seed harvested after their seedpods have changed from pink to a dull yellow, indicating that they are fully mature. Performs best on moist, free-draining clay and loam soils of an acid to neutral nature, generally with a pH of 4.5 to 7.0, and on sites with full to partial sun exposure.

Problem features

Hollock is listed as a weed in at least one reference publication and is reported to have naturalised in Puerto Rico. Still, there does appear to be any records of it anywhere as a serious weed, despite its widespread introduction and cultivation. It is assessed as a low weed risk species for Hawaii by the Hawaii Pacific Weed Risk Assessment (HPWRA) project.

Books

• Champion, H. G. & Seth, S. K. 1968, A revised survey of the forest types of India, Natraj Publishers, Dehradun, India

• Francis, J. K. 1998, Tree species for planting in forest, rural, and urban areas of Puerto Rico, U.S. Department of Agriculture, Forest Service, International Institute of Tropical Forestry, Río Piedras, Puerto Rico

• Francis, J. K. and Liogier, H. A. 1991, Naturalized exotic tree species in Puerto Rico, General technical report SO-82, USDA Forest Service, Southern Forest Experiment Station, New Orleans

• Krishen, P. 2006, Trees of Delhi : a field guide, Dorling Kindersley Publishers, Delhi

• Little, E. L. & Skolmen, R. G. 1989, Common forest trees of Hawaii (native and introduced), Agricultuural Handbook No. 679, Forest Service, U.S. Department of Agriculture, Washington, D.C.

• Luna, R. K 1996, Plantation trees, International Book Distributors, Dehradun, Uttarakhand

• Randall, R. P. 2002, A global compendium of weeds, R.G. and F.J. Richardson Press, Melbourne

• Randall, R. P. 2007, The introduced flora of Australia and its weed status, Cooperative Research Centre for Australian Weed Management, Glen Osmond, South Australia

• Scheffer, T. C & Morrell, J. J. 1998, Natural durability of wood : a worldwide checklist of species, Forest Research Laboratory, Oregon State University, Corvallis, Oregon