Tulipa sylvestris L. (Liliaceae)


Wild tulip

Lithograph of Tulipa sylvestris (Graves and Hooker, 1835, 'Flora Londinensis', vol. 5). Tulip tepals of 'divers colours', collected by Jacob Bobart the Elder in the 1680s, from the Oxford Botanic Garden (Oxford University Herbaria).

Tulipa sylvestris is the most abundant and widespread European tulip, and extends into North Africa and southwestern Asia although its native range is unknown. In the UK, Tulipa sylvestris is not native. It has been in cultivation since at least the late sixteenth century but was only recorded from the wild at the end of the eighteenth century. However, it is likely Tulipa sylvestris was naturalized long before its formal discovery in the wild. Today, it is rarely found in the wild.

As western garden plants, the genus Tulipa has been favoured since the sixteenth century, although rulers of Persia and the Ottoman Empire had a penchant for the genus long before this. Famously, tulips became associated with the speculative folly known as tulipomania. During a three-year period (1634-1637) Dutch speculators created a market where enormous prices were paid for individual tulip bulbs. In February 1637 the market collapsed, to the ruin of some. We now know that the petal patterns of some of the most highly prized tulips were because of viral infection.

However, there is more to tulips than horticulture and economics. At the end of the nineteenth century, using early time-lapse photography, the German botanist Wilhem Pfeffer, started to investigate the circular movements made by plants, including tulips, as they grow.

Decades earlier Charles Darwin had painstakingly plotted such movements in hundreds of species and reported his observation in his final work, The Power of Movement in Plants (1880). Darwin coined the term 'circumnutation' for the phenomenon, reporting that the extent and speed varies among species. Tulips circumnutate approximately every four hours, whilst the model plant Arabidopsis circumnutates between 15 minutes and 24 hours. Darwin could not explain circumnutation but concluded it was fundamental to a 'plant's physiology'.

In 1968 Anders Johnsson and Donald Israelsson proposed an alternative explanation; gravity powers circumnutation. However, Johnsson had to wait nearly 40 years, and the facilities on board the International Space Station, to test his hypothesis. Rather than tulips, Arabidopsis seeds were germinated in a special chamber for studying the long-term effects of gravity and the seedlings photographed to monitor their exact positions. In the near weightlessness of the Space Station, minute circumnutation was observed. Darwin was right, the phenomenon was hardwired but gravity was essential to amplify the effect. This was confirmed by placing space-grown seedlings in a centrifuge to mimic gravity and observing that circumnutation increased in magnitude.

Further reading

Johnsson A et al. 2009. Gravity amplifies and microgravity decreases circumnutations in Arabidopsis thaliana stems: results from a space experiment. New Phytologist 182, 621-629.

Pavord A 1999. The tulip. Bloomsbury.

Pfeffer W 1898-1900. Studies of plant movement. Kinetoscope Archives.

Stephen Harris

BBC Radio Oxford clip about this week's plant