The Wardian Case

Until the middle of the 19th century, plant hunters traveling in distant lands were able to send samples home only by preserving them first. Insects had to be killed and pinned to cards, and plants pressed and dried to make herbarium specimens. It was possible to send plant seeds on journeys lasting many weeks or even months, but there was no guarantee that they would germinate on arrival. By the latter half of the century the situation had changed. Collectors were able to send living specimens across the world, knowing they would reach their destinations in perfect condition.

The device that made this possible was the terrarium—a tightly sealed container for living plants and small land-dwelling animals. The terrarium was invented by Nathaniel Bagshaw Ward (1791–1868) and was more often called a Wardian case. Ward was a physician and possibly also a surgeon working in the East End of London, and he devoted his spare time to botany and entomology. He was particularly fond of ferns, but found these almost impossible to grow in his small garden owing to the amount of smoke and soot polluting the city air. Ward made his discovery when he tried to save a moth pupa by creating a natural environment for it inside a sealed jar. He did not record the fate of the moth, but after it had been in the jar for some time Ward noticed blades of grass and a fern growing in the soil at the bottom. He left them there, with the jar sealed, to find out how long they would survive, having realized that the plants were able to live because he had isolated them from the outside—and polluted—air. Ward wrote to Sir William Hooker at Kew Gardens describing what he had done, and he commissioned a carpenter to construct a container to his specification. This would comprise a wooden frame supporting glass windows on all sides and on top. He wished the frame to fit together as tightly as possible, and Ward stipulated that the hardest wood should be used, to prevent it decaying from the condensation and tropical warmth.

Two of the cases were delivered, and in July 1833 Ward filled them with local ferns and grasses and despatched them to Sydney, Australia. Six months later the cases arrived, and the plants inside them were thriving. Ward's Australian collaborator emptied the cases, cleaned them thoroughly, filled them with Australian plants, and in February 1835 they sailed for London. This time the voyage took eight months, and severe storms subjected the cases to a severe battering. Nevertheless, the plants arrived alive and growing well. Ward described his success in a small pamphlet, and in 1842 he published a book On the Growth of Plants in Closely Glazed Cases. His book attracted wide interest and his cases became very popular—and in the following years increasingly ornate. In 1854 Ward lectured on them to a meeting of the Royal Horticultural Society held at the Chelsea Physic Garden.

From that time, living plants could be sent around the world safely. Wardian cases were used to transport rubber trees from Brazil to Kew and from Kew to southern Asia, tea plants from China to India, and many ornamental plants from the Tropics to Europe. Ward became Master of the Society of Apothecaries, a fellow of the Linnean Society, and a fellow of the Royal Society.