It’s a bloom with a phew
When I was answering gardening questions at Agfest a few weeks back, an enthusiastic young gardener asked me to name the rarest plant in the world so that he could grow it. What a question! There are so many rare and unusual plants including rare orchids, endangered plants from every climate zone around the world and a growing number of rare indoor plants that can cost thousands to buy online.
There are also rare bulbs including snowdrops. Gardeners who covet rare snowdrops have their own name of ‘galanthaphile’, from the plant’s genus name galanthus.
But for a young gardener those suggestions didn’t cut the mustard. The rare plant that sprang to my mind was the titan arum. As well as being rare and hard to grow, this plant takes many years to flower and, when it does, it’s guaranteed to an attract a crowd, because its enormous flower literally stinks! It smells of rotting meat and gives this flower its common names of carrion or corpse flower.
Adding to its appeal for a gardener wanting to grow a rare plant is that the titan arum (amorphophallus titanium) produces the world’s largest unbranched flower and grows from the largest corm in the world. The spathe-shaped flower stands 3m high from a burgundy red fleshy petal skirt. The corm can weigh 50kg, but larger corms are recorded – including one growing at the Edinburgh Botanic Gardens that weighs in at 153.9kg.
Because it comes from the tropical rainforests of Sumatra in Indonesia, it needs a glasshouse environment in temperate climates. It is grown in glasshouses in botanic gardens around the world, including Adelaide Botanic Garden in Australia. The titan arum takes five to 10 years of growth before flowering.
When word gets out that a titan arum is about to flower (and it’s really popular on social media), visitors flock to see it and form long queues.
The dreadful smell is designed to attract flies and beetles to pollinate the flower, which not only smells but also looks like rotting meat. The smell of the flower is strongest at night when these pollinating insects are most active.
After flowering, the corm produces a large single leaf that can stand 6m high and reach 5m across. If the flower was pollinated it develops seeds. It can take another five to 10 years to bloom again.
NOT SO RARE
Although the titan arum is rare and unusual, there are many other arums that grow in gardens. Several are weedy rather than rare, including lords and ladies (arum italicum). This arum spreads by seed and small underground woody corms. It is a small plant, no more than 30cm high, that produces a white flower in summer followed by a stem of bright orange berries. Leaves appear after flowering and can be plain green or variegated.
Once this arum is in the garden it is very hard to control. Numbers can be reduced by removing small plants (including the underground corm), removing flowering or fruiting stems and smothering clumps with cardboard and mulch. Cut off leaves, lay down cardboard, cover with mulch and leave for at least a year.
There is another stinky arum that appears in gardens. This is the dragon arum (dracunculus vulgaris). Although not nearly as potently scented as the titan arum, it still smells as if something has died. There are several that pop up in my garden each spring that trick me. As I start to search for whatever’s died in the garden, I remember the trick and look around for the blood-red flower, patterned stems and green palmate leaves. Dragon arum comes from the Mediterranean region but grows without much fuss in our cool temperate climate. Corms are planted in autumn.