Helianthus Lenticularis

Helianthus Lenticularis Plant Information

Helianthus Lenticularis grows in the following 51 states:



The plant has an erect rough-hairy stem, reaching typical heights of 3 metres (9.8ft). The tallest sunflower on record achieved 9.17 metres (30.1ft). Sunflower leaves are broad, coarsely toothed, rough and mostly alternate. What is often called the "flower" of the sunflower is actually a "flower head" or pseudanthium of numerous small individual five-petaled flowers ("florets"). The outer flowers, which resemble petals, are called ray flowers. Each "petal" consists of a ligule composed of fused petals of an asymmetrical ray flower. They are sexually sterile and may be yellow, red, orange, or other colors. The flowers in the center of the head are called disk flowers. These mature into fruit (sunflower "seeds"). The disk flowers are arranged spirally. Generally, each floret is oriented toward the next by approximately the golden angle, 137.5, producing a pattern of interconnecting spirals, where the number of left spirals and the number of right spirals are successive Fibonacci numbers. Typically, there are 34 spirals in one direction and 55 in the other; however, in a very large sunflower head there could be 89 in one direction and 144 in the other. This pattern produces the most efficient packing of seeds mathematically possible within the flower head.
A model for the pattern of florets in the head of a sunflower was proposed by H. Vogel in 1979. This is expressed in polar coordinates
The sunflower, Helianthus annuus, genome is diploid with a base chromosome number of 17 and an estimated genome size of 2871-3189 Mbp. Some sources claim its true size is around 3.5 billion base pairs (slightly larger than the human genome).
A common misconception is that flowering sunflower heads track the Sun across the sky. Although immature flower buds exhibit this behaviour, the mature flowering heads point in a fixed (and typically easterly) direction throughout the day. This old misconception was disputed in 1597 by the English botanist John Gerard, who grew sunflowers in his famous herbal garden: "[some] have reported it to turn with the Sun, the which I could never observe, although I have endeavored to find out the truth of it." The uniform alignment of sunflower heads in a field might give some people the false impression that the flowers are tracking the sun.
This alignment results from heliotropism in an earlier development stage, the bud stage, before the appearance of flower heads (anthesis). The buds are heliotropic until the end of the bud stage, and finally face East. Their apparent heliotropic motion is a circadian rhythm, synchronized by the sun, which continues if the sun disappears on cloudy days or if plants are moved to constant light. If a sunflower plant in the bud stage is rotated 180, the bud will be turning away from the sun for a few days, as resynchronization by the sun takes time. The heliotropic motion of the bud is caused by unequal growth speed of the flower stalk and only occurs before the flowers open. The motion of the 'nodding' buds is irreversible, but cumulative. When growth of the flower stalk stops and the flower is mature, the heliotropisms also stops and the flower faces east from that moment onward. This eastward orientation allows rapid warming in the morning and, as a result, an increase in pollinator visits. Sunflowers do not have a pulvinus below their inflorescence. A pulvinus is a flexible segment in the leaf stalks (petiole) of some plant species and functions as a 'joint'. It effectuates leaf motion due to reversible changes in turgor pressure, which occurs without growth. The sensitive plant's closing leaves are a good example of reversible leaf movement via pulvinuli.
In today's market, most of the sunflower seeds provided or grown by farmers are hybrids. Hybrids or hybridized sunflowers are produced by crossbreeding different types and species of sunflower, for example crossbreeding cultivated sunflowers with wild species of sunflowers. By doing so, new genetic recombinations are obtained ultimately leading to the production of new hybrid species. These hybrid species generally have a higher fitness and carry properties or characteristics that farmers look for, such as resistance to pathogens.

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