Quercus leucotrichophora

A. Camus

Bluejack Oak, Grey oak, Himalayan oak

Fagaceae Edible: Seeds, Nut, Sap - manna Potential hazards — see below 381 iNaturalist observations

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Summary

Quercus leucotrichophora is a tree belonging to Family Fagaceae; commonly known as Banjh oak, Banj oak (Uttarakhand) and Ban oak (Himachal). In Nepal, it is known as Banjhi, Rainj, Khasarant, Tikhe bhanjh in standard Nepali and Sulsing in Tamang language. It is classified in subgenus Cerris, section Ilex. Some authors named it as Quercus incana Roxburgh, which is now treated as a synonym.

Description

A large tree. It grows 18 m high. It loses many of its leaves during the year. The bark is dark grey and cracked. The leaves are leathery. They have sharp teeth along the edge. Older leaves turn dull grey-green. The leaves are smooth an top and pale with downy hairs underneath. Male and female flowers are separate. They are on the same tree. The male flowers are in slender spikes that droop. These are 8 cm long. The female flowers occur singly and do not have stalks. The fruit is an acorn. The nut is enclosed by a cup. The nut is about 2 cm long. It is hairy when young but becomes shiny brown.

Edible Uses

The seeds, about 2.5cm long, are cooked before eating. They can be dried, ground into a powder, and used as a thickening in stews or mixed with cereals for making bread. The seeds contain bitter tannins that must be leached out by thoroughly washing in running water, though this also removes many minerals. Either whole seeds or ground powder can be used. Leaching whole seeds can take several days or even weeks; wrapping them in a cloth bag and placing them in a stream is one well-established method. Grinding to powder speeds the process, and a simple taste test shows when enough tannin has been removed. The traditional approach was to bury seeds in boggy ground overwinter and dig up the germinating seeds in spring once their astringency had mostly gone. Roasted seeds serve as a coffee substitute.

Traditional Uses

The sweet manna is used in confectionery.

This uses section is brief — help expand it

Medicinal Uses

The seeds are astringent and diuretic, and are used in the treatment of gonorrhoea, indigestion, diarrhoea, and asthma. Any galls produced on the tree are strongly astringent and can be used in the treatment of haemorrhages, chronic diarrhoea, and dysentery.

Known Hazards

Leaching seeds removes bitter tannins but also eliminates minerals.

Distribution

It is a temperate plant. It needs cool climates. It can grow on hot and dry hillsides. It usually grows between 1,200-2,400 m altitude in the Himalayas. Kyneton Botanical Gardens. Melbourne Botanical gardens. Hobart Botanical gardens.

Where It Grows

Asia, Australia, Himalayas*, India, Myanmar, Nepal, Pakistan, SE Asia, Tasmania,

Cultivation

Prefers a good deep fertile loam which can be on the stiff side. Young plants tolerate reasonable levels of side shade. Tolerates moderate exposure, surviving well but being somewhat stunted. This species is not hardy in the colder areas of the country, it tolerates temperatures down to between -5 and -10°c. Prefers warmer summers than are usually experienced in Britain, trees often grow poorly in this country and fail to properly ripen their wood resulting in frost damage overwinter. Trees can be coppiced if their trunks are up to 25cm in diameter. The seed ripens in its first year. Intolerant of root disturbance, trees should be planted in their permanent positions whilst young. Hybridizes freely with other members of the genus. Plants in this genus are notably resistant to honey fungus.

Propagation

Seed loses viability quickly if allowed to dry out. It can be stored moist and cool overwinter, but is best sown as soon as it is ripe in an outdoor seed bed with protection from mice and squirrels. Small quantities can be sown in deep pots in a cold frame. Because plants develop a deep taproot, they should be moved to their permanent positions as soon as possible — trees sown in situ produce the best results. Do not leave trees in a nursery bed for more than 2 growing seasons, as they transplant very poorly after that point.

Other Uses

A mulch of the leaves repels slugs and grubs, though fresh leaves should not be used as they can inhibit plant growth. Oak galls, caused by insect larvae living inside them, provide a rich source of tannin once the insect has left, and can also be used as a dyestuff. The bark contains up to 23% tannin by dry weight. The wood is hard and red-brown in colour but warps and splits badly during seasoning; it is used for furniture and agricultural implements. It also makes good fuel and good charcoal.

Notes

There are about 600 Quercus species.

Synonyms

Quercus incana Roxb.

Also Known As

Banjh, Ban

References (7)

Dobriyal, M. J. R. & Dobriyal, R., 2014, Non Wood Forest Produce an Option for Ethnic Food and Nutritional Security in India. Int. J. of Usuf. Mngt. 15(1):17-37
Krishen P., 2006, Trees of Delhi, A Field Guide. DK Books. p 62
Manandhar, N.P., 2002, Plants and People of Nepal. Timber Press. Portland, Oregon. p 388
Plants for a Future database, The Field, Penpol, Lostwithiel, Cornwall, PL22 0NG, UK. http://www.scs.leeds.ac.uk/pfaf/
Riviera Sci. 22:66. 1935

Show all 7 references

Sahni, K.C., 2000, The Book of Indian Trees. Bombay Natural History Society. Oxford. p 171
Tewari, D.N., 1994, Important Plants of India. International Book Distributors, India. p 42