The joy of sunflowers

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Walking through Hebden Bridge this late summer’s afternoon, I am amazed at the vibrancy and sizes of the sunflowers, protruding from the wildflower beds which glisten along the edges of the park like glittering confections of multicoloured candy, writes horticulturalist, author and poet Simon Zonenblick.

Some as high as people, they beam at me with huge fiery faces, their densely packed seedheads encircled by long yellow petal-like ligules, so that the flowerheads look just like frazzly summer suns.

These zesty, zany, irresisitible plants are somehow both unusual in apppearance, yet so familiar.

Sunflowers, of the family Helianthus, are native to North America, where they often grow in prairies and first appeard in present-day Arizona and Mexico as far back as 3000BC, but have been grown here in Britain, as well as in many other countries, since around the 16th Century, when they were distributed by Spanish explorers. The plant we are used to seeing is Helianthus annuus, whose seeds can be used for oil production and ground into cakes and breads - in 19th Century Russia, for example, sunflower production accounted for millions of acres, and Western Europe remains a major market for sunflower oil today.

In his 1597 Herbal, English botanist John Gerard noted how some observers “have reported (sunflowers) to turn with the Sun, which I could never observe, although I have endeavored to find out the truth of it,” which brings us to a curious aspect of the plant.

It is widely believed that H. annuus tilts towards the sun, but in fact this is noted only in immature sunflowers, whose flowerheads bend to the light in a motion known as heliotropism.

Most developing plants will naturally grow towards the light, but what distinguishes heliotropic plants such as the Alpine buttercup flower (Ranunculus adoneus), Arctic poppy (Papaver radicatum) and indeed the common sunflower is that the flowerheads actually turn as if slowly rotating, as they track the movement of the sun.

Ingeniously, this behaviour is engineered by microscopic “motor cells” within the pulvinus - a flexible stem part below the leaves and flowers which acts as a kind of muscle. The flowers themselves are densely packed compact infloresences comprising an inner ring of disc florets, and sterile outer ray florets. Once mature, the flowerheads face east, and sunflowers can grow as high as three metres.

I’ve seen several in the valley this summer which have almost equalled this.

Giants of the plant world, sunflowers tower over flowerbeds and survey the expanses of parks like sturdy beanstalks.

Bold, slightly garish, sucking in sunlight and oozing lemony colours like bright, shining suns, these spectacular paragons of the prairies bring a certain pizzazz to the greyness of a rainy English summer’s afternoon.

Indeed, it is surely impossible to imagine a world without sunflowers.