Helianthus annuus

The plant is 0.5 to 2.5 m tall, little branched and rough-haired, with nodding flower heads 10 to 40 cm across borne singly or in small numbers.

Info Flora gives the flowering time of sunflower in Switzerland as July to September.

The Czech Pladias database gives a flowering period of June to September and insect pollination.

Info Flora classes the sunflower as a cultivated neophyte that appeared in Switzerland after 1500 and originates from North America.

In Switzerland it is cultivated and escapes to waste ground, railway embankments and path edges in the hill zone.

In a French trial of 34 oilseed hybrid cultivars, mean nectar sugar secreted per floret ranged from 101 to 216 micrograms, varying by up to 100 percent among cultivars.

The same French paper reports that an average of 0.2 bees per head is sufficient to maximise sunflower seed yield and oil content.

An analysis by researchers at the University of Pretoria, South Africa, found the protein content of sunflower pollen relatively low compared with other important bee forage plants.

The authors conclude that although sunflower offers abundant and accessible pollen, its quality may hinder bee development when it is the exclusive pollen source.

In a North American study, a sunflower pollen diet dramatically and consistently reduced Crithidia bombi infection in the bumble bee Bombus impatiens.

Unifloral sunflower honey is bright yellow of medium colour intensity and crystallises quickly and often hard because of its high glucose content.

The Bavarian 'Bienenweide Bayern' seed mix for flower areas includes sunflower at 8.5 percent and specifies an open-flowered, pollen-bearing variety.