florapedia / flower-facts / how do sunflowers reproduce

November 15, 2012

How Do Sunflowers Reproduce?

Sunflowers include a large group of flowers belonging to the genus Helianthus. With more than 60 varieties including H. annuus, H. giganteeus and the H. maximiliani, these sun-lovers grow up to 12 feet high. Each plant produces a massive solitary bloom often reaching diameters of 2 feet. Growers harvest seeds from the center of the yellow, orange or black seeds. In nature, this show plant relies on bees and other insects for reproduction.

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Busy Bees

Once the plant has flowered, usually in summer, it produces a sweet pollen mixture that lures bees and other insects. When the bees arrive, they get their feet wet with the pollen as they drink the plant’s nectar. The plant relies on the sperm-producing pollen coming into contact with the egg-containing stigma. The yellow pollen is transferred from the insect’s hairy legs to the stigma. This is the first step in sunflower reproduction.

Sperm Meet Egg

Once the pollen is forced down the stigma, it releases sperm into the stigma. An available egg receives the sperm, and the egg is fertilized with a meat-bearing seed. The pollen/sperm can belong to the original plant or may come from another sunflower. Self-Pollinating Self-pollination is a mechanism that this flower uses to stay alive. On the occasion where the stigma receives no pollen, the stigma will twist and wrap itself around its own pollen. Seeds created by self-pollination will only produce flowers that look like the original plant, so no hybridization will have occurred.

Time Factor

Sunflowers are fast reproducers, and one plant can create dozens of others. Plant seeds about an 1 inch below the ground. Germination occurs quickly, usually between 5 and 10 days, but spring crops produce more plants than summer crops. Spring crops are planted in April and May. Summer crops go in the ground in June and July. When the back of the plant’s head turns brown, it is ready for harvesting.