Helianthus
| Sunflowers | |
|---|---|
 | |
| Genus: | Helianthus |
| Family: | Asteraceae |
| Type: | Herbaceous perennials and annuals |
| Weediness: | Some species are weedy |
| Pollination: | Insects |
The genus Helianthus comprises 67 species and several subspecies in the Asteraceae family, all of which are native to North America, with some species (particularly Helianthus annuus (sunflower) and Helianthus tuberosus (Jerusalem artichoke)) cultivated in Europe and other parts of the world as food crops and ornamental plants.
Description
[edit | edit source]These are usually tall, annual or perennial plants, growing to a height of 60–390 cm. The rough and hairy stem is branched in the upper part. The petiolate leaves are dentate and often sticky. The lower leaves are opposite, ovate or often heart-shaped. The upper leaves are alternate and narrower.
They bear several to many wide, terminal capitula (flower heads), with bright yellow ray florets at the outside and maroon disc florets inside. The flower heads face in the direction of the sun, moving from east to west during the day.
Growing conditions
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[edit | edit source]Pests and diseases
[edit | edit source]w:list of Lepidoptera which feed on Helianthus.
