pierre laszlo

Ehretia thyrsiflora Nakai (Boraginaceae)

This fifteen to twenty foot tall shrub, which originated in China and Japan, displays a slim trunk arched like a dancer’s body. Its saw-edged leaves are large and ogival rather than oval, resembling a Gothic nave in cross-section. During early summer, it displays big pa-nicles of small white scented flowers.

Georg Dionys Ehret (1708-1770), after whom this genus is named, was a German naturalist and painter. A contemporary of Carl von Linnaeus, in 1736, he published a collection of images of plants, ordered after the systematics pioneered by Linnaeus.

Scientific illustrations were a prime manifesto of the Enlightenment. They conveyed its values, a defiance of censorship as still enforced by the authorities, the desire to represent nature accurately, and a sense of wonder at the sight of the beautiful, whether that of na-tural or of man-made objects.

The images which Ehret provided of plants, avowedly as a propagandist for the then brand-new Linnean systematics, thus focussed on the criteria for identification of a spe-cies, viz. flowers and fruit. Ehret fulfilled this self-imposed program with alacrity, levity and enormous talent. He depicted flowers with an erotic sensuality and with an anthropo-centrism which, for not springing to mind at first sight, given the sheer beauty of the plates he created, is nevertheless lascivious. To Ehret, a flower is an attractive and sen-suous model. She offers herself to the viewer, she unfolds her limbs, she strikes a pose of abandon, an attitude of reclining repose.

The Ehretia genus belongs to the family of Boraginaceae. Some species from that family and from the Asteraceae and Leguminosae families produce 1,2-dehydropyrrolizidine al-kaloids. These nitrogen-containing natural products and their N-oxides are potent poi-sons, primarily to herbivores. Livestock in Australia, South Africa, South America and the United States have been affected through damage to the liver. In addition, contamination of grain crops by such plants has resulted in large-scale incidents of food poisoning in humans. The attendant morbidity and mortality are both high, especially in Africa and in central and south Asia, with recent episodes in Afghanistan and also, possibly, Ethiopia. In developed countries, there is a threat of low-level contamination by these alkaloids. The likely consequences are, in the absence of overt toxicity to the liver, the onset of progressive, chronic diseases. 

Ehretia plants are thus both a memorial to a great artist in a reputedly minor genre, botanic illustration, and, very much so, an actual threat to mankind on several continents. It is not readily appreciated that natural products can be extremely toxic. In the public eye, man-made chemicals put people at risk. This conventional and widespread view is so narrow-minded as to make us, collectively speaking, become unaware of very real dangers.