The ginkgo has swimming sperm and survived the Hiroshima bomb
The ginkgo is the last survivor of a plant order that appeared more than 290 million years ago. It fertilises its seeds with sperm that swim using thousands of tiny hairs, some trees outlived the Hiroshima atomic bomb, and even its name comes from a spelling slip made in seventeenth-century Nagasaki.
Ginkgo biloba is a gymnosperm native to East Asia and widely called a living fossil; closely similar fossils date back about 170 million years to the Middle Jurassic. Once thought extinct in the wild for centuries, it may still survive naturally in a few genetically diverse mountain populations in southwestern China. Its fan-shaped leaves are unique among seed plants, with veins that fork repeatedly in two but never join into a network, and in autumn they turn deep saffron yellow before dropping, sometimes within a single day.
Reproduction is strikingly ancient. Trees are either male or female, although branches occasionally switch sex. Pollen travels by wind, but the final step relies on motile sperm, as in ferns and cycads; Sakugoro Hirase, a Japanese botanist, spotted them in 1896. Each sperm, roughly 70 to 90 micrometres across, is driven by thousands of beating flagella. The resulting seeds sit inside a fleshy coat laced with butyric acid, which smells like rancid butter to people but attracts squirrels, palm civets and raccoon dogs that spread the seeds.
Toughness defines the tree. It resists disease and wind, sprouts from buds near its base after erosion, and can grow aerial roots that clone the tree when they touch soil; in one surveyed semiwild stand, 40 percent of trees were multi-stemmed. Specimens older than 1,600 years have been measured, and the largest are estimated at over 3,500. A 2020 Chinese study of trees up to 667 years old found no genetic signs of ageing. Its draft genome, published in 2016, holds 10.6 billion letters, more than three times the human total.
The name puzzle was solved relatively recently. Engelbert Kaempfer recorded the tree in Nagasaki in 1690, and his odd '-kgo' spelling was long blamed on him, but Nagata and colleagues showed it followed his interpreter's local dialect. Linnaeus adopted it in 1771. Ginkgo supplements are widely sold for memory, though clinical evidence is limited except possibly for dementia, and the seeds carry real poisoning risks.
Source: Ginkgo biloba
