1. Helianthus annuus L.

    1. Native to North America, Helianthus annuus, better known as sunflower, is both beautiful and useful. It is widely cultivated for its edible seeds and oil and, to a lesser extent, as an ornamental. Nutritionally, the seeds contain up to 46% of polyunsaturated oil with a high percentage of linoleic acid and up to 20% protein of a high biological value. Sunflower belongs in the daisy family, Compositae (Asteraceae), and is characterised by having a flower head (capitulum) with outer yellow ray florets, which serve to attract pollinators, and inner brownish disc florets which are fertile and are arranged in spiral whorls from the centre of the head. Sunflower is pollinated by bees and some farmers place bee colonies in sunflower fields which produce honey as a by-product.

[FTEA]

Compositae, H. Beentje, C. Jeffrey & D.J.N. Hind. Flora of Tropical East Africa. 2005

Habit
These escapes are small annual herbs, 20–120 cm high.
Leaves
Leaves alternate, ovate, to 8 x 3.5 cm and scabridulous to the touch, petiolate.
Capitulum
Capitula terminal and solitary; ray florets ± 14, yellow, 35 x 10 mm; disc florets very many, yellow orange.
Note
In cultivation the plant and all its parts may become much larger. Both the cited specimens came from road-sides. Sunflower, originally from America, is cultivated in many places in East Africa for its seeds, as an oil crop. Occasionally it seems to escape and become naturalised, as in T 6, Uzaramo District: Dar es Salaam on airport road, Apr. 1977, Wingfield 3392a! and T 8, Songea District: Mkaku River SW of Kitai, Mar. 1956, Milne-Redhead & Taylor 9075!.
Figures
Fig. 143 (page 707).
[KSP]

Kew Species Profiles

General Description
Sunflower is a beautiful and nutritious plant widely cultivated for its edible seeds and oil.

Native to North America, Helianthus annuus, better known as sunflower, is both beautiful and useful. It is widely cultivated for its edible seeds and oil and, to a lesser extent, as an ornamental. Nutritionally, the seeds contain up to 46% of polyunsaturated oil with a high percentage of linoleic acid and up to 20% protein of a high biological value. Sunflower belongs in the daisy family, Compositae (Asteraceae), and is characterised by having a flower head (capitulum) with outer yellow ray florets, which serve to attract pollinators, and inner brownish disc florets which are fertile and are arranged in spiral whorls from the centre of the head. Sunflower is pollinated by bees and some farmers place bee colonies in sunflower fields which produce honey as a by-product.

It is a common misconception that sunflower heads are heliotropic and track the sun across the sky. The alignment of sunflowers in a field is due to heliotropism at an earlier stage of their development, while the flower heads are still in bud. The buds follow the sun until the end of the bud stage when they finally position themselves facing east. This behaviour makes blooming sunflowers growing in the open like living compasses with north to the left, west behind and south to the right. 

Species Profile

Geography and distribution

Sunflower was first domesticated from its wild ancestor more than 5,000 years ago in the south-western part of the USA and, within a short period of time, became widespread throughout the Americas. Its value as an ornamental plant and use as a source of food and oil attracted the attention of European explorers who brought the crop to Europe in the 16th century.

By the 19th century sunflower was being cultivated on a wide scale in Russia, the Ukraine and Caucasus regions for the manufacture of edible vegetable oil. The crop is still important in that part of the world today along with the US and Argentina. Other key producers are India, China, Turkey, the European Union (eg France, Spain) and South Africa. Occasionally, sunflower escapes cultivation and becomes naturalized.

Habitat

Cultivated in relatively cool temperate to warm subtropical climates. Sunflowers can also be grown in the drier tropical regions but are unsuitable for humid environments. They can grow in a wide range of soils from sandy to clayey provided they are deep, free-draining and not acidic. 

Description

Overview: Helianthus annuus is an annual herb which grows up to 5 metres tall with a well-developed taproot extending up to 3 metres into the soil. The stem is erect with a slight-to-severe curve below the flower head in mature plants. In many wild types it is branched whereas in cultivated varieties the stem is unbranched.

Leaves:The leaves are positioned opposite each other in the lower part of the plant and higher up the stem they are arranged spirally. Each leaf is hairy, 10–30 × 5–20 cm with toothed margins, and is supported by a long petiole. 

Flowers:The inflorescence is a terminal head (capitulum), 10-50 cm in diameter and is surrounded by three rows of bracts (phyllaries). The flower head is comprised of outer yellow ray florets, which serve to attract pollinators, and inner brownish disc florets which are fertile. The inner florets are numerous and are arranged in spiral whorls from the centre of the head. Each floret is about 2 cm long and consists of a 5-lobed, brown or purplish corolla tube and two deciduous bristly scales (pappus), 5 stamens united into a tube and an ovary which is positioned below the flower tube and stamens. The stigma has two curved lobes and there are nectaries at the base of the style. 

Fruit:The fruit (known botanically as an achene) is up to 15-25 mm in size and can be white, brown, black or striped.

Uses

Sunflower is mainly cultivated for its tasty seeds and versatile oil and to a lesser extent for ornamental purposes.

The seeds yield edible oil, which is excellent quality due to a high proportion of unsaturated fatty acids, near absence of toxic substances, light colour and good flavour. The oil is used for salads, cooking and as an ingredient in the manufacture of margarine. The oil also has some industrial uses as drying oils for paints and varnishes and in the manufacture of soaps and cosmetics as well as a biofuel.

The by-product of sunflower oil extraction is a high protein meal, which is commonly blended with soyabean meal and used as livestock feed.

Sunflower meal is sometimes used as a substitute for wheat flour in the baking of bread and cakes for human consumption. The indigenous people of North America have a long tradition of using ground sunflower seeds to make bread-like products.

The varieties cultivated for their seeds are much larger than the oil-cultivars and are often black and white striped, are can be eaten directly. In countries like Russia, the sunflower seeds are salted and roasted whole and enjoyed as a delicious savoury snack. 

The smaller seeds are widely used in birdseed and in pet food. Some people air-dry the fruiting capitula and hang them upside down or simply leave the fruiting capitula on the plants for bird feed. Sunflower is sometimes cultivated as a forage crop.

Crop wild relatives of sunflower

The Millennium Seed Bank and the Global Crop Diversity Trust are engaged in a ten-year project, called 'Adapting Agriculture to Climate Change'. The project aims to protect, collect and prepare the wild relatives of 29 key food crops, including sunflower, so that they are available to pre-breeders for the development of new varieties that are more resilient to the effects of climate change.

Millennium Seed Bank: Seed storage

The Millennium Seed Bank Partnership aims to save plants worldwide, focusing on those plants which are under threat and those which are of most use in the future. Once seeds have been collected they are dried, packaged and stored at -20°C in our seed bank vault.

Description of seeds:Average 1,000 seed weight = 42 gNumber of seed collections stored in the Millennium Seed Bank:OneSeed storage behaviour:Orthodox. (The seeds of this plant can be dried to low moisture contents without significantly reducing their viability. This means they are suitable for long-term frozen storage such as at the MSB)Germination testing:Successful

Helianthus annuusis one of the species included in the ‘Difficult Seeds' project because many of its seeds are short-lived and may not survive a long time in storage. 

This species at Kew

Pressed and dried specimens of sunflower are held in Kew's Herbarium, where they are available to researchers by appointment. Details and images of some of these specimens can be seen online in Kew's Herbarium Catalogue.

Distribution
USA
Ecology
Cultivated in relatively cool temperate to warm subtropical climates. More information below.
Conservation
Widespread in cultivation, rarely naturalizing.
[KSP]
Use
Oil, food, livestock feed, biofuel.

Images

Distribution

Found In:

Alabama, Arizona, Arkansas, Belize, California, Colorado, Connecticut, Delaware, District of Columbia, Florida, Georgia, Honduras, Idaho, Illinois, Indiana, Iowa, Kansas, Kentucky, Louisiana, Maine, Maryland, Masachusettes, Mexico Central, Mexico Gulf, Mexico Northeast, Mexico Northwest, Mexico Southeast, Mexico Southwest, Michigan, Minnesota, Mississippi, Missouri, Montana, Nevada, New Hampshire, New Jersey, New Mexico, New York, North Carolina, North Dakota, Ohio, Oklahoma, Oregon, Pennsylvania, Rhode I., South Carolina, South Dakota, Tennessee, Texas, Utah, Vermont, Virginia, Washington, West Virginia, Wisconsin, Wyoming

Introduced Into:

Alaska, Albania, Alberta, Altay, Amur, Argentina Northeast, Argentina Northwest, Argentina South, Assam, Austria, Baltic States, Belarus, Bolivia, Botswana, British Columbia, Bulgaria, Buryatiya, Cape Provinces, Caprivi Strip, Central European Rus, Chile Central, Chile North, Chile South, China North-Central, China South-Central, China Southeast, Chita, Corse, Denmark, East European Russia, East Himalaya, Finland, France, Free State, Germany, Great Britain, Greece, Hainan, Hungary, India, Ireland, Irkutsk, Italy, Japan, Kamchatka, Kazakhstan, Khabarovsk, Kirgizstan, Korea, Krasnoyarsk, KwaZulu-Natal, Lesotho, Libya, Magadan, Manchuria, Manitoba, Morocco, Namibia, Nepal, Netherlands, New Brunswick, New South Wales, New Zealand North, New Zealand South, Newfoundland, North Caucasus, North European Russi, Northern Provinces, Northern Territory, Norway, Nova Scotia, Nunavut, Ontario, Paraguay, Peru, Poland, Primorye, Prince Edward I., Qinghai, Queensland, Québec, Romania, Sakhalin, Sardegna, Saskatchewan, Sicilia, South Australia, South European Russi, Spain, Swaziland, Sweden, Switzerland, Tadzhikistan, Tasmania, Tibet, Transcaucasus, Turkey, Turkey-in-Europe, Turkmenistan, Tuva, Ukraine, Uruguay, Uzbekistan, Victoria, West Himalaya, West Siberia, Western Australia, Xinjiang, Yakutskiya, Yugoslavia

Common Names

English
Sunflower

Helianthus annuus L. appears in other Kew resources:

Date Identified Reference Herbarium Specimen Type Status
Jan 1, 1993 Barros, C.S.S. [141], Alagoas K000054458
Harrison, S.G., USA 40698.000
Hoehne, W. [s.n.], Brazil K001031314
Hoehne, W. [s.n.], Brazil K001031315
Lindheimer, F. [259], Texas K001092048 Unknown type material
Lindheimer, F. [259], Texas K001092049 Unknown type material
Lindheimer, F. [259], Texas K001092050 Unknown type material
Lindheimer, F. [s.n.], Texas K001092051 Unknown type material
Lindheimer, F. [259], Texas K001092052 Unknown type material
s.coll. [Cat. no. 3192] K001118761
s.coll. [Cat. no. 3192] K001118762

First published in Sp. Pl. 2: 904 (1753)

Accepted in:

  • [1] GCC (2011) Global Compositae Checklist . http://compositae.landcareresearch.co.nz/.
  • [5] Flora of North America Editorial Committee (2006) Flora of North America North of Mexico 21: 1-616. Oxford University Press, New York, Oxford.

Literature

  • [2] Beentje, H. (2010). The Kew Plant Glossary: an Illustrated Dictionary of Plant Terms. Royal Botanic Gardens, Kew.
  • [3] Mabberley, D.J. (2008). Mabberley’s Plant-book: a Portable Dictionary of Plants, their Classification and Uses. Third edition. Cambridge University Press, Cambridge.
  • [4] Royal Botanic Gardens, Kew (2008). Seed Information Database (SID). Version 7.1.
  • [6] Polikarpov, G.G. (1978). Sunflower’s blooming floscule is a compass. Nature 272: 122
  • [7] (1959) Flora of the USSR 25: 1-628. Science Publishers, Inc..

Sources

Flora of Tropical East Africa
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Kew Species Profiles
Kew Species Profiles
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[C]

Kew Library Art and Archives
[D] Digital Image © Board of Trustees, RBG Kew http://creativecommons.org/licenses/by/3.0/

World Checklist of Selected Plant Families
World Checklist of Selected Plant Families(2016). Published on the Internet http://apps.kew.org/wcsp/
[E] See http://kew.org/about-kew/website-information/legal-notices/index.htm You may use data on these Terms and Conditions and on further condition that: The data is not used for commercial purposes; You may copy and retain data solely for scholarly, educational or research purposes; You may not publish our data, except for small extracts provided for illustrative purposes and duly acknowledged; You acknowledge the source of the data by the words "With the permission of the Trustees of the Royal Botanic Gardens, Kew" in a position which is reasonably prominent in view of your use of the data; Any other use of data or any other content from this website may only be made with our prior written agreement. http://creativecommons.org/licenses/by-nc-sa/3.0
[F] © Copyright 2016 International Plant Names Index and World Checkist of Selected Plant Families. https://creativecommons.org/licenses/by/3.0