Avena sativa (oat)
Oat is cultivated throughout the temperate world, to produce food for livestock and humans, and even as an ingredient for cosmetics.
Avena sativa L.
This domesticated cereal is widely cultivated in temperate regions.
A major cereal and fodder crop since ancient times. Oat is an ingredient of a wide range of food products, such as breakfast cereals, porridge, biscuits and breads. Oat is also used in preparations to treat dry skin.
Oat can be tolerated by most (but not all) people who are gluten intolerant. Oat is frequently processed near other grains (such as wheat), so there are risks associated with contamination from gluten sources.
About this species
Oat (Avena sativa) is one of a number of species of domesticated and wild oats in the genus Avena (the members of which are collectively known as oats). Oat is descended from A. sterilis, a wild oat that spread as a weed of wheat and barley from the Fertile Crescent (a region spreading from Israel to western Iran) to Europe. It was domesticated about 3,000 years ago, in the wetter, colder conditions of Europe, in which oats thrive, and soon became an important cereal in its own right on the cooler fringes of Europe.
Geography & Distribution
Domesticated oats have been traced back to Bronze Age Europe, and are now cultivated around the temperate world.
Avena sativa is an annual with erect culms (stems) 40–180 cm long. Its leaves are cauline (arise from the upper part of the stem). The ligule (appendage between the sheaf and blade of the leaf) is a hairless membrane, 3–6 mm long. The leaf-blades are 14–40 cm long and 5–15 mm wide. The leaf-blade surface is minutely rough-textured on both sides. The tip of the leaf-blade tapers to a point.
The inflorescence is an open, pyramidal, loosely spreading, nodding panicle, 20-40 cm long and 5-15 cm wide. The primary panicle branches are drooping. The spikelets (clustered units of flowers and bracts) are solitary and pendulous. The spikelets are pedicelled (have a stalk attaching them to the main stem of the inflorescence); the pedicels are filiform (thread-like).
The spikelets consist of 2 or 3 fertile florets, and are wedge-shaped, laterally compressed, 22–27 mm long and persistent on the plant. The glumes (empty bracts that enclose the florets) extend past the tip of the florets, and are thinner than the fertile lemma (principal bract enclosing the flower). The upper and lower glumes are both lance-shaped, 22–27 mm long, membranous, without keels and 7–9 -veined.
The fertile lemma is lance-shaped, leathery, 15–17 mm long, much thinner above, without a keel and is 7–9 -veined. The surface of the lemma is scaly, rough above and hairless. The flowers have three anthers and an ovary which is hairy all over. The fruit is a caryopsis (simple dry fruit) with an adherent pericarp (outer layer). The fruit is hairy all over and has a linear hilum (scar marking the point of attachment).
Threats & Conservation
Avena sativa is not considered to be threatened.
In medieval Britain, oats were widely grown for bread, biscuits, and malting, but they now hold their importance only in the wetter parts of northern Europe. Oats have also had an important role since the Roman period as feed for horses. British emigrants introduced oat cultivation to North America in the 17th century, but they have always been a minor cereal outside Europe. Today, the biggest oat-producing countries are the Russian Federation, Canada and the United States. Oat bran is rich in a type of dietary fibre that has been shown to reduce cholesterol levels, and this has led to increased interest in its consumption. Oat grain is an ingredient in a wide range of food products, such as breakfast cereals, porridge, biscuits, breads and baby foods, and is also used as a meat extender. Oats are also used in external preparations to treat eczema and dry skin.
Being tolerant of low soil fertility and frost, and requiring low external inputs (such as fertilizers), Avena sativa has been suggested as a potential food and fodder crop for resource-poor farmers in areas such as the highlands of tropical Africa. In some areas, however, such as in Victoria, Australia, parts of North America, and in the Karoo-Namib region of southern Africa, wild oats have become invasive and are a threat to native species of grasses and herbs.
Red oat or Turkey oat, Avena byzantina, is also descended from A. sterilis. Although sometimes considered to be the same species as A. sativa, red oat is genetically distinct and has a different distribution including, as the name suggests, Turkey. However, red oat has been largely replaced by A. sativa in recent years.
Four minor cultivated species are derived from wild forms of A. strigosa grown in the western Mediterranean. Bristle oat, A. strigosa, is a fodder plant in central and northern Europe, and is still grown in the Shetland Islands, but is almost extinct. A. brevis and A. hispanica are now very rare crops of southwest Europe. A. nuda is a naked form of oat that threshes free of the tough husk. It has low yields and is not widely cultivated.
A. abyssinica is only found in Ethiopia. It grows as a tolerated weed of other cereals, mainly barley, and is now in the course of domestication.
The grass family (Poaceae)
The grass family (Poaceae, or Gramineae) is one of the most economically important plant families. It provides most of our food in the form of cereals (for example, wheat, rice, barley, oats, millet, maize, sorghum) and sugar (sugar cane). In addition, grasses feed our cattle, provide the basis for most of our alcoholic drinks, as well as building materials (bamboo), thatch, and straw. A number of grasses yield essential oils (lemongrass) and raw materials for cosmetics (oats).
Millennium Seed Bank: Seed storage
Kew's Millennium Seed Bank partnership aims to save plant life world wide, focusing on plants under threat and those of most use in the future. Seeds are dried, packaged and stored at a sub-zero temperature in our seed bank vault.
Description of seeds: Average 1,000 seed weight = 31.5 g.
Number of seed collections stored in the Millennium Seed Bank: One.
Seed storage behaviour: Orthodox (the seeds of this plant survive being dried without significantly reducing their viability, and are therefore amenable to long-term frozen storage such as at the MSB)
Germination testing: Successful
Composition values: Oil content 4 - 11.8%. Protein content 13.2 - 24.4%.
Oats are very hardy and can be sown in November. At Kew, A. sativa is propagated in pots in a nursery, and seedlings are planted outside as soon as they are large enough to handle, because if kept indoors they can produce leggy growth. A compost mix containing 10% screened and sterilised loam, 45% coir and 45% Silvafibre is used, and Osmocote and Kieserite are added. A. sativa seeds can also be sown in spring, and will complete their life cycle within 12 months.
Oats at Kew
Grass garden at Kew (Image: RBG Kew)
Avena sativa can be seen, along with other cereal crops, growing in Kew's Grass Garden by the Davies Alpine House. The best times to visit the Grass Garden are early summer for the annual grasses and cereals, and autumn and winter for the perennial grasses, when these have produced their seed heads.
FAO/WHO Food Standards: Codex Alimentarius, in particular CODEX STANDARD 118 – Codex Standard for Foods for Special Dietary Use for Persons Intolerant to Gluten
References & Credits
Bown, D. (2008). The Royal Horticultural Society Encyclopedia of Herbs and their Uses. Dorling Kindersley, London.
Clayton, W.D., Harman, K.T. & Williamson, H. (2006 onwards). GrassBase - The Online World Grass Flora. http://www.kew.org/data/grasses-db.html. [accessed 29 May 2010; 21:45 GMT].
Groves, R.H., Boden, R. and Lonsdale, W.M. (2005). Jumping the garden fence: Invasive garden plants in Australia and their environmental and agricultural impacts. CSIRO report prepared for WWF-Australia. WWF-Australia, Sydney. 173 pp. Also available as a download here.
Main image: Licensed under the Creative Commons Attribution-Share Alike 2.5 Generic license.
Prance, G. & Nesbitt, M. (eds) (2005). The Cultural History of Plants. Routledge, London.
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