Orchid defies gravity for survival

The pink-flowered Holcoglossum amesianum reproduces in an adverse climate by twisting its male sexual organ so that it can fertilise the female.

Chinese scientists have discovered an orchid that reproduces in an adverse climate by twisting its male sexual organ so that it can fertilise its female organ.

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In what is believed to the first known case in the plant world, a pink-flowered orchid, Holcoglossum amesianum, defies gravity by turning its anther through 360 degrees in order to insert pollen at its tip into the female cavity, the stigma.

H amesianum grows in tree trunks at altitudes of between 1,200 and 2,000 metres (3,900-6,500 feet) in Yunnan province where, during its flowering season of February to April, the weather is usually bone-dry and windless.

In such conditions, pollen cannot be borne on a breeze to fertilise plants, and as the orchid's flowers produce no scent or nectar, they do not attract bees and other insects which could carry the pollen around.

The plant's clever form of self-pollination "is likely to be an adaptation to the orchid's dry and insect-scarce habitat and may be widespread among species growing in similar environments," suggest the authors, led by Huang Laiqiang of Tsinghua University, Shenzhen, southern China.

The study is published on Thursday in Nature, the British weekly science journal.