Wednesday 28 Apr 2021. I recently visited Guilfoyle’s Volcano, an ornamental reservoir – and a triumph of form and function – located in the southeastern corner of Melbourne’s magnificent Royal Botanic Gardens.

Guilfoyle’s Volcano was originally built in 1876 by William Guilfoyle, the director of the gardens at the time. The inspiration for Guilfoyle’s design was perhaps the volcano he saw in the New Hebrides (today’s Vanuatu) during a voyage to the South Pacific in 1868. In creating a reservoir-cum-folly, he had sought, he said, “to combine the useful with the ornamental.”

Guilfoyle built his volcano in the highest part of the Botanic Gardens, with gravity serving to channel water downhill to hoses at various points. In this way he attempted to address the absence of a consistently reliable water source for the gardens, despite the proximity of the Yarra River, which had long been the gardens’ primary source. Unfortunately the volcano was not to be it: it took too long to refill. In the 1880s the downstream levelling of falls across the Yarra River to allow for shipping brought salt water upstream and imperilled the gardens. Happily, a pumping station built further upstream at Dight’s Falls provided the gardens with fresh Yarra water once again. In the 1950s the gardens were connected to Melbourne’s mains water supply, and the volcano fell into disuse. In the early 1980s it was emptied and fenced off, and became overgrown.

Then, in the 1990s, plans were made to revive the volcano, and in 2008 the project received funding. Finally in 2010 Guilfoyle’s Volcano reopened as part of a broader stormwater capture, filtration and reticulation system. From Domain Road to the south of the gardens stormwater is gravity-fed to Nymphaea Lily Lake, from where it continues to flow to Central Lake and thence to Ornamental Lake; and from Anderson Street to the east of the gardens stormwater is gravity-fed into Ornamental Lake. From Ornamental Lake water is pumped up to the volcano. Meanwhile, the volcano gravity-feeds water into Nymphaea Lily Lake. As the water thus circulates it passes through wetlands, which act as natural filters, as do the floating islands inside the volcano. Brilliant!

Notwithstanding the primary role of Guilfoyle’s Volcano in this clever water-management system, it is its extraordinary visual appeal that will doubtless prompt most visitors’ interest. It is indeed not only useful but spectacularly ornamental, an architectural and horticultural marvel planted out in a beautiful and bewildering array of xerophytes, plants adapted to live in arid landscapes, such as cactuses and succulents. These plants not only look splendid but are wonderful options for Australian gardens.

All manner of cactuses, succulents and other dry-tolerant plants flow down the sides of the volcano and line the wooden boardwalk that carries visitors to the summit with its floating islands.

The Torch Cactus (Echinopsis spachiana), for example, is an impressive, tall species from Argentina, while the Agave ocahui x Agave attenuata has fleshy, barbed leaves that make it look something like a monstrous Venus flytrap.

My favourite though is the attractive, plump, almost perfect Golden Barrell Cactus (Echinocactus grusonii) is the Volcano’s star attraction. It is endemic to east-central Mexico, where it is rare and endangered, according to Wikipedia. It can reach one metre in height. Apparently the specimens at the Volcano still have plenty of growing to do.

Adjacent to the volcano are two meeting places planted with groves of curious Queensland Bottle Trees (Brachychiton rupestris), growing in harmonious arrangement among rocks so placed as to enable sitting and chatting or just contemplating.

After an hour spent in this most beautiful garden, on this gorgeous mid-autumn day, I felt elated and ready to cycle the eleven or so kilometres home.