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21 March 2019

From aspirin to opium: many of our medicines originally came from plants and some are still exclusively extracted from plants. Nuts, goji berries and hemp seed – we can’t get enough of these products since they have attained the status of superfood, and a lot of people hope they can eat themselves healthy by consuming them. But there is sometimes a very fine line between health and indulgence, medicine and poison, and care is often warranted. There is no scientific proof for the healing properties of quite a few of the plants that are regarded as medicinal. And what if a plant does work and suddenly becomes extra valuable for mankind – how do we ensure that there is a sufficient supply without depleting natural sources? The Hortus botanicus Leiden will be highlighting plants and health in the exhibition ‘Better with plants’ from 16 May to 27 October.


Plants as medicine

Medicinal plants have been part of the collection at the Hortus ever since it was first laid out in 1594. There are many plants in the Hortus that are relevant to the theme ‘Better with plants’. In the Clusius Garden, the starting point for the exhibition, we will explore the subject of medicinal plants from Europe; in the Systematic Garden we will be looking at poisonous and healing substances in various plant families; and in the tropical glasshouses you can find information about medicinal plants from the tropics. And there is, of course, news about ongoing research, because we are still searching for new compounds and investigating their application.


Research in collaboration with the China Academy of Chinese Medical Sciences

We are carrying out research into medicinal plants in collaboration with the Institute of Biology Leiden (Leiden University) and with the China Academy of Chinese Medical Sciences in Beijing. China, along with Indonesia, is an Asian pilot country for the University, and the focus of the plant collections in the Hortus is on plant collections from Asia. The researchers are curious about active chemical compositions in all kinds of plants. In China, DNA-barcoding is being applied to some of our collection. This is a molecular technique for the recognition of species via a standard, short segment of their DNA. There is a special label bearing Chinese characters for plants that have been investigated, along with a QR code that takes you to background information about the plant.


Online tour and walking tour guide and map

A variety of sources of information are available to accompany the exhibition. Along with an online walking tour, which you can consult via the Hortus website, there will soon be a printed walking tour guide, available in English, Dutch and Chinese. This includes descriptions of 30 plants that have been investigated in collaboration with Beijing University. Visitors will receive a map that shows a route past a number of highpoints: from

Aloe vera, which so enthralled the 17th century Dutch botanist Herman Boerhaave, to orchids that are currently the subject of research into medicinal compounds. These maps have been sponsored by the health and care foundation ‘Stichting Zorg and Zekerheid’. The walking tour guide and the map are available free of charge from the cash desk.


Children’s walking tour: Poisonous, Green and Healthy

A is available from the cash desk in which children can read about plants, how they work and where they can be found in the Hortus. This booklet also lets children discover which plants are good for them and which are actually very poisonous.


Witches’ Carpet designed by the artist Diana Scherer

The artist Diana Scherer designs works of art with roots. She is fascinated by plant root systems, and in combination with scientific research and photography this has resulted in an exhibition of beautiful works of art with roots. She designed a Witches’ Carpet for the Hortus, inspired by the principal ingredients in the salve known as witches flying ointment, such as deadly nightshade, mandrake and henbane. The exhibit will be sown on 16 May and will be on display in the geophyte glasshouse. In the past, Diana Scherer has exhibited in galleries that include the Victoria and Albert Museum in London.



The summer exhibition has been made possible thanks to contributions from the Friends of the Hortus, the Leiden Municipality and the Stichting Zorg en Zekerheid foundation.


Collaboration with the National Museum of Antiquities (RMO): Medieval gardens

From 3 May to 1 September you can visit the exhibition ‘Medieval gardens’ in the National Museum of Antiquities (RMO) in Leiden; this includes stories about plants, herbs and the splendour of flowers in the Middle Ages, from Europe to the Middle East and ends up in the Clusius Garden in the Hortus. In the Hortus you can follow a walking tour route past a number of ‘medieval’ plants from the Hortus collection; specialists from the RMO have looked into the symbolism of these plants. If you would like to visit both exhibitions you can purchase a combination ticket for EUR 12.50 from the cash desk at either institution or via the Hortus website.


Collaboration with other botanical gardens

As in previous years, many of the 26 gardens that are members of the Dutch Botanical Gardens Association (NVBT) have the same theme. Along with the other gardens we are compiling a book of drinks recipes based on plants from our collections. Visit for more information.


Summer programme

All of our regular events – such as the Hortus plant market (Saturday 11 May), Museum night (Saturday 18 May), Midsummer’s night (Friday 21 June) and the Night of discoveries (Saturday 21 September) – will feature activities based on the theme ‘Better with plants’. The walk-in guided tours every Thursday in July and August will highlight our ‘Crown Jewels’ but will also focus on plants that are associated with health.


Science Cafés 16 May and 27 September from 14:00 to 17:00

This year the Hortus will be organizing two Thursday afternoon Science Cafés. A Science Café is a market-like meeting with activities, short talks and guided tours taking you past plants connected with health.


For our complete programme of activities, please visit



Editorial note (not for publication): for further information please contact the PR & Communication Department, or T. +31 (0)71-5275231. Visual material can be downloaded via ‘Pers – Beter met planten’.



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