| Friday, January 4, 2008 |
| Extreme close-up of sunflower head in Istanbul, Turkey |
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posted by Flora Fun @ 6:35 AM   |
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| Sunflowers in Manila, Philippines |
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| posted by Flora Fun @ 6:35 AM |
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| Heliotropism |
Sunflowers in the bud stage exhibit heliotropism. At sunrise, the faces of most sunflowers are turned towards the east. Over the course of the day, they move to track the sun from east to west, while at night they return to an eastward orientation. This motion is performed by motor cells in the pulvinus, a flexible segment of the stem just below the bud. As the bud stage ends, the stem stiffens and the blooming stage is reached.
Sunflowers in the blooming stage are not heliotropic anymore. The stem has frozen, typically in an eastward orientation. The stem and leaves lose their green color.
The wild sunflower typically does not turn toward the sun; its flowering heads may face many directions when mature. However, the leaves typically exhibit some heliotropism. |
| posted by Flora Fun @ 6:35 AM |
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| Red sunflowers. |
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| posted by Flora Fun @ 6:34 AM |
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| A sunflower farm near Mysore, India. |
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| posted by Flora Fun @ 6:34 AM |
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| Other species |
The Jerusalem artichoke (Helianthus tuberosa) is related to the sunflower.
The Mexican sunflower is Tithonia rotundifolia.
False sunflower refers to plants of the genus Heliopsis. |
| posted by Flora Fun @ 6:34 AM |
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| Lone sunflower about 2 m (6 ft, 6') tall |
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| posted by Flora Fun @ 6:33 AM |
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| Sunflowers growing near Fargo, North Dakota |
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| posted by Flora Fun @ 6:33 AM |
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| Cultural usage |
The sunflower is the state flower of the U.S. state of Kansas, and one of the city flowers of Kitakyushu, Japan.
The sunflower is often used as a symbol of green ideology, much as the red rose is a symbol of socialism or social democracy. The sunflower is also the symbol of the Vegan Society. |
| posted by Flora Fun @ 6:32 AM |
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| Bumble bee sampling Sunflower nectar |
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| posted by Flora Fun @ 6:32 AM |
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| Sunflower head displaying florets in spirals of 34 and 55 around the outside |
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| posted by Flora Fun @ 6:32 AM |
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| Size |
| Sunflowers most commonly grow to heights between 2.5 and 3.5 m (8 - 12'). Scientific literature reports, from 1567, that a 12 m (40'), traditional, single-head, sunflower plant was grown in Padua. The same seed lot grew almost 8 m (24') at other times and places (e.g. Madrid). Much more recent feats (past score years) of over 8 m (25') have been achieved in both Netherlands and Ontario, Canada. |
| posted by Flora Fun @ 6:31 AM |
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| Sunflower |
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| posted by Flora Fun @ 6:31 AM |
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| Scientific classification |
Kingdom: Plantae
Class: Magnoliopsida
Order: Asterales
Family: Asteraceae
Genus: Helianthus
Species: H. annuus |
| posted by Flora Fun @ 6:31 AM |
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| Sunflower Fun |
| Welcome to Sunflower Fun!!! |
| posted by Flora Fun @ 6:30 AM |
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