How knowledge grows

This is illustrated by an exhibition in Berlin's Botanical Gardens with the subtitle "Alexander von Humboldt and the roots of knowledge production". Exhibits and an audio station help visitors explore how botanical knowledge comes about and its relevance today. Was Humboldt really the inventor of infographics, and what do plants have to do with it?

Alexander von Humboldt and his travel companion Aimé Bonpland would have given a lot for one blossom of this tree. They offered an ounce of gold as a reward, but to no avail. Even without the blossoms, however, they described the Brazil nut tree for posterity, having come across it in May 1800 at the mouth of the Casiquiare River in today's Venezuela. And they brought back with them leaves from this plant they hadn't seen before, known today by the scientific name Bertholletia excelsa. One such leaf can be found in the herbarium at Berlin's Botanical Gardens, whose specimens from around the world form the basis for fruitful botanical research. More than 3000 botanical specimens collected by Humboldt are kept here to this day.

In Humboldt's 250th anniversary year the Botanical Museum is now holding an exhibition titled "How knowledge grows", in which the universal scholar is presented as a producer of knowledge in the field of botany. A very modest one, mind you. "Of all your friends the dearest, in botany your disciple," Humboldt wrote in Latin in the autograph book for his mentor Carl Ludwig Willdenow, whom he often consulted on botanical matters.

Pioneers of botany

The exhibition, curated by Patricia Rahemipour and Kathrin Grotz, is housed in a small caravan near the main greenhouse, its modest dimensions belying the wealth of interesting details it contains.   Such as the fact that Humboldt and Bonpland not only collected herbarium specimens to preserve information about living plants, but also experimented with imaging techniques like nature printing, applying a thin layer of ink to reveal the most delicate structures of leaves or blossoms. This method only became widespread in the late 19th century – another pioneering achievement.

Visitors also learn that the seven-volume American travel journals contain 4527 consecutively numbered entries and sketches of plants collected, in chronological order – the same numbers that are found on the herbarium specimen labels. A method of documentation created by Humboldt and Bonpland that has become the standard procedure in botanical field research today.

"How knowledge grows" also offers illuminating insights into a number of plants. The storage organ of the dahlia, for example, was an Aztec delicacy in Mexico. When a dahlia blossomed in Berlin from seeds sent by Humboldt in 1804, however, this knowledge had been lost. Gardeners and botanists were mainly interested in cultivating new varieties of dahlia for decorative purposes. 

On the roots of knowledge

At the heart of the exhibition is an audio station where visitors can play twelve episodes of the Roots of Knowledge podcast, co-produced by young adults. It looks, for example, at the cinchona, a tree that particularly impressed Humboldt and Bonpland on their American journey. The plant contains quinine (a substance found today above all in tonic water) and was at the time a valuable pharmaceutical plant used to treat fever and malaria. Inspired by conversations with his colleagues in Bogotá, Humboldt even changed his itinerary to visit a region in Loja (in today's Ecuador) where it grew.

Another episode is devoted to the curare plant and its poison, vividly described by Humboldt in Relations historique. The Strychnos guianensis, fatal only when it came into direct contact with blood, was boiled down by the indigenous peoples of South America to create an intoxicating decoction. "Every now and then an Indian urged us to sample the liquid", the natural scientist noted.

The exhibition paints a vivid picture of the American journey in general, not just in terms of Humboldt's botanical discoveries. 2700 kilometres covered in 75 days in a dugout canoe with four indigenous rowers and a helmsman. A journal page with water stains is shown, and the podcast cites Humboldt's descriptions of a passage so turbulent the travellers feared for their lives ("We thought we were all lost, yet we retained our composure").

The only one of his kind

No less significantly, "How knowledge grows" also tells the story of Humboldt's extensive networks and connections, of contemporaries who inspired him, and vice versa. Among them was Goethe: "One could not learn in eight days from books what he tells one in an hour," the poet enthusiastically wrote of his friend, who was twenty years his junior. Their shared love of botany no doubt played a role. Goethe's poem "Gingo biloba" from West-Eastern Divan, with the bifurcated leaves of the ginkgo tree pasted on the original, is evidence of this.

And Goethe wrote a line about Humboldt that perfectly sums up his entire scientific career: "One may say he is the only one of his kind."

The exhibition continues until 29 March 2020. The opening hours are the same as those of the Botanical Gardens, daily from 9 a.m. to 8 p.m.