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Sunflower

Introduction

Everyone remembers this splendid plant from having admired it, at least for once, among abandoned places, fields and roadsides. In children, then, this species arouses great curiosity, due to its bright colors, and its very high stem that emerges from the green of the fields, turning its flowers towards the sun. We are talking about the sunflower, an annual plant of very ancient origins much appreciated by growers and gardeners. Known for its large size, the sunflower can perform an interesting ornamental function both in a vegetable garden and in a private garden. The plant, in fact, lends itself to being grown both in pots and in the open field. Whether wild or cultivated, the sunflower is also a species that lends itself to infinite uses, both herbal and industrial.

Features


Sunflower is a plant native to South America. The exact geographical origins of this species are not known, some sources speak of Brazil, others of Peru or Mexico. What is certain is that the sunflower was cultivated and revered by the ancient South American populations, while the “conquistatores” imported it to Europe around the year 1500. Belonging to the asteraceae family, the sunflower is a herbaceous plant with an annual cycle. Its full botanical name is Heliantus annuus. Within the genus Heliantus there are more than 20 thousand species, both annual and perennial, even if the sunflower heliantus annuus, as the name implies, has an annual development cycle. The annual varieties are about a hundred. The name of the plant derives from “helios” which means “flower” and from “anthos” which means “flower”. The two Greek terms refer to the sunflower flower’s characteristic of always following the direction of the sun. This peculiarity is also called heliotropism. In reality, what we all know as the sunflower flower, and which should follow the solar direction, is a flower head formed by several flowers distributed both in the central part (the disk) and in the external part (the rays). The flowers of the disc have a brown color, while those of the rays, which appear as petals, have a color ranging from golden yellow, to intense yellow, to orange. Both the disc flowers and the external ones have a vegetal structure known as corolla. In the external flowers the corolla is narrow and lanceolate and it is precisely that which gives the shape of rays to the petals, while in the part of the disc it is formed by toothed tubules. The disc flowers are bisexual, while the outer ones are sterile. The sunflower also has a long stem or stem with a fairly thick diameter, even ten centimeters. The stem reaches a height of two meters, but in some species it can abundantly exceed even four meters. The leaves of the sunflower are large, oval, slightly lanceolate and arranged in the lower and opposite part of the stem. From the maturation of the disc flowers, seeds are formed, which have variable colors, from white to yellow and black. The round, blackish parts, which we all know as seeds, are, on the other hand, the fruits of the sunflower, or the achenes that contain the seeds. The stem reaches a height of two meters, but in some species it can abundantly exceed even four meters. The leaves of the sunflower are large, oval, slightly lanceolate and arranged in the lower and opposite part of the stem. From the maturation of the disc flowers, seeds are formed, which have variable colors, from white to yellow and black. The round, blackish parts, which we all know as seeds, are, on the other hand, the fruits of the sunflower, or the achenes that contain the seeds. The stem reaches a height of two meters, but in some species it can abundantly exceed even four meters. The leaves of the sunflower are large, oval, slightly lanceolate and arranged in the lower and opposite part of the stem. From the maturation of the disc flowers, seeds are formed, which have variable colors, from white to yellow and black. The round, blackish parts, which we all know as seeds, are, on the other hand, the fruits of the sunflower, or the achenes that contain the seeds.

Variety


Different varieties of the sunflower are known, some hybrid and others natural. Among these we remember the heliantus decapetalus, the heliantus tuberosus, the heliantus multiflorus and the heliantus pauciflorus. The former has a smaller flower head than the heliantus anuus. Present in Piedmont, it is also called simple sunflower. The double sunflower is, on the other hand, the heliantus multiflorus. This variety has many radius flowers on the outside and is present in Friuli. Helantus tuberosus is similar to heliantus annuus or common sunflower. It is called the sunflower of Canada, but it is present in any part of Italy. Heliantus pauciflorus is also called a wild sunflower. Perennial species with lanceolate leaves, it is easily found in the islands of Southern Italy. The sunflower hybrids are created and studied in the laboratory to obtain plants with characteristics different from the original ones. In the laboratory, hybrids have been obtained that grow on soft and sandy soils, when the common sunflower usually grows on compact and clayey soils. Among the most famous hybrids we mention heliantus deserticola, heliantus anomalus and heliantus paradoxus. It should also be remembered that many sunflower seeds are obtained from genetically modified hybrids. The sunflower with its head facing the sun can also act as a pest for many crops, such as soybeans. For this reason, growers prefer varieties with the head facing down and with a less annoying vegetative cycle. In the laboratory, hybrids have been obtained that grow on soft and sandy soils, when the common sunflower usually grows on compact and clayey soils. Among the most famous hybrids we mention heliantus deserticola, heliantus anomalus and heliantus paradoxus. It should also be remembered that many sunflower seeds are obtained from genetically modified hybrids. The sunflower with its head facing the sun can also act as a pest for many crops, such as soybeans. For this reason, growers prefer varieties with the head facing down and with a less annoying vegetative cycle. In the laboratory, hybrids have been obtained that grow on soft and sandy soils, when the common sunflower usually grows on compact and clayey soils. Among the most famous hybrids we mention heliantus deserticola, heliantus anomalus and heliantus paradoxus. It should also be remembered that many sunflower seeds are obtained from genetically modified hybrids. The sunflower with its head facing the sun can also act as a pest for many crops, such as soybeans. For this reason, growers prefer varieties with the head facing down and with a less annoying vegetative cycle. It should also be remembered that many sunflower seeds are obtained from genetically modified hybrids. The sunflower with its head facing the sun can also act as a pest for many crops, such as soybeans. For this reason, growers prefer varieties with the head facing down and with a less annoying vegetative cycle. It should also be remembered that many sunflower seeds are obtained from genetically modified hybrids. The sunflower with its head facing the sun can also act as a pest for many crops, such as soybeans. For this reason, growers prefer varieties with the head facing down and with a less annoying vegetative cycle.

Flowering and reproduction


The common sunflower blooms from July to October. Its reproduction occurs through two very natural methods: pollination and dispersion. The first method is achieved thanks to the transport of pollen by winged insects, including bees, while the dispersion is achieved by dropping the seeds on the ground. These, in turn, are brought back to the plant thanks to the ants.

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