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Helianthus annuus selection map. USDA tree Database.

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A. Facility of head showing dual spiral sample of fruit (seeds) and yellow pollen top top stamens. Photo by David D. Taylor.

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B. Tree in ruderal habitat follow me railroad line. Picture by David D. Taylor.

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C. Underside that head showing coarse bracts. Picture by David D. Taylor.

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D. Closeup that stem showing hairs. Photograph by David D. Taylor.


Common Sunflower (Helianthus annuus L.)

By David Taylor

Common sunflower is a member of the Asteraceae, the Sunflower family. In enlarge manuals and guides, this household is referred to as the Compositae due to the fact that the "flowers" are a composite of many flowers, frequently of different types. The many types of tree in this family members are grouped based upon the plan and type of flowers. All members the the family create one or much more heads (capitulum, the term supplied in technological keys) of flowers. This and other sunflowers have actually two different varieties of flowers, beam flowers and also disk flowers and in turn, these deserve to have male and female parts, or one of two people one or the other. The beam flowers look favor petals, yet each is in reality an separation, personal, instance flower. The disc flowers are at the facility of the head, inside the ring of beam flowers. The key flowers are usually small. V a hand lens one have the right to see the unique tips of 5 petals in every flower. The disc flower closest to the beam flowers open up first. There are 52 varieties of sunflowers, all aboriginal to north America and also Mexico.

This sunflower is 1 to 3 meters (ca. 39 to 118 inches) high (cultivated develops often taller). The stem is stiff, and also usually coarsely hairy (see photo D), often more than 2.5 centimeters (1 inches) in diameter. Leaves are mainly alternate, more comprehensive at the base 보다 the top, and also are 10 to 40 centimeters (4 to 15.75 inches) lengthy by 5 to 40 centimeters (2 come 15.75 inches) wide. The leaves space toothed and also covered in short, unstable hairs above. Single heads space borne in ~ the finish of branches. Every head generally has 13 come 30 beam flowers that are 2.5 to 5 centimeters (1 to 2 inches) long, and 150 to an ext than a thousand-disc flowers. Both the ray and disc flowers are yellow (reddish beam in some cultivated forms). The facility of the head include the disk flowers is 1.5 to 2.5 mm (0.6 come 1 inches) wide. The entire head is 4.5 to 10.5 centimeters (1.8 to 4.1 inches) wide, much broader in grew forms. The involucral bracts under the head are big and irpari (see picture C). This is among the bigger sunflowers uncovered in phibìc America.

Common Sunflower is an open up land species, normally on moist soils. That is a types of prairies and other grasslands, old fields, roadsides, rail rights-of-way, savannas, and forest edge. That is found across the conterminous U.S., but probably is aboriginal to the main and southern portion of the selection and Mexico. The is likewise found together an development from Nova Scotia to British Columbia, Northwest Territories, Alaska, and also Hawai’i. It is cultivated and also has escaped in lot of the world.

This types flowers in July come October depending upon the part of the nation in which the is found. Plenty of bees, beetles and also rarely butterflies room attracted to this plant. Finches, small mammals and also insects eat the seeds. The tree is annual, reseeding chin in to an ideal areas.

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Many points in the plant human being are arranged in a path that complies with the Fibonacci series (pine cone scales, individual part of pineapples, garden increased petals). This series of numbers complies with the sample 1, 2, 3, 5, 8, 13, 21, 34, 55…, whereby each succeeding number is the amount of the ahead two. The spiral sample of the key flowers/fruits the this types is one example. The fruits space arranged in two groups of spirals, one come the left and one to the best (see center of photo A). If one counts the number of left hand spirals, and then the number of right hand spirals, the 2 numbers will be next-door neighbors in the collection (typically 21 / 34, 34 / 55, or 55 / 89). A internet search for ‘Fibonacci series in nature’ will carry out links to much more information.