Belfast Botanic Gardens

The Royal Horticultural Society (RHS), in its earlier form as the Horticultural Society, sponsored several plant collectors in the 19th century to seek new plants for British gardens and scientific study

. The RHS Plant Collector Archive details the journeys of 12 such individuals. 

Notable collectors sponsored by the RHS and their collection regions included John Potts in China and India, George Don across West Africa, the Caribbean, and the Americas, and John Damper Parks in China. David Douglas collected in North America, while James McRae explored Hawaii and South America. Karl Theodor Hartweg collected extensively in the Americas, and Robert Fortune focused on China. Other collectors sponsored or associated with the RHS in the 19th century included John Forbes, John Jeffrey, Matteo Botteri, John Weir, and Thomas Cooper. Later, the RHS also provided part-sponsorship for collectors like George Forrest, who worked in southwestern China. The RHS's Digital Collections provide further details on these expeditions and the plants gathered RHS Digital Collections. 

The Belfast Botanic Gardens (and other botanic gardens in the UK/Ireland) were the initial introduction points for the invasive New Zealand flatworm (Arthurdendyus triangulatus) into the British Isles, likely arriving hidden in soil with imported plants from New Zealand, and then spreading from these gardens to nurseries, garden centers, and eventually farms, devastating local earthworm populations. 

Key Points:

• Origin & Introduction: The flatworm is native to New Zealand and was first recorded outside of its homeland in Belfast in 1963, presumed to be transported with ornamental plants like daffodils or rhododendrons.

• Spread from Botanic Gardens: Similar introductions occurred in Scotland, with the Edinburgh Botanic Garden being a key early site, acting as a hub from which the flatworms spread via the horticultural trade (potting soil, container plants).

• Impact: As a predator, the New Zealand flatworm preys on native earthworms, reducing their numbers significantly, which negatively affects soil aeration, drainage, and nutrient cycling, impacting soil health and potentially wildlife that rely on earthworms.

• Invasive Status: It's a regulated invasive species, and it's illegal to keep, breed, or release it in Northern Ireland due to its detrimental effects on native ecosystems. 

In essence, the botanic gardens served as unintentional gateways for this harmful invasive species into the UK and Ireland, disrupting local ecosystems.