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Joseph Dalton Hooker - The Megaherbs

Bulbinella rossii, by PlantExplorers.com
staff illustrator, William Lovegrove

First described by Joseph Hooker while on the epic Antarctic voyage of the Terror and Erebus under Captain James Ross, these strange plants were not so startling for their size, but for their size relative to where they grew. Named 'Megaherbs' by Captain Ross, these unusual plants may not seem large when compared to their tropical counterparts, but when you stop to consider that they are growing on the Subantarctic Islands of New Zealand, they do seem oddly large for the harsh climate they thrive in.

During the 1800's, to increase the chances of survival for possible shipwreck survivors, many uninhabited islands were stocked with goats, sheep, rabbits and other grazing animals, as a potential source of food for the hapless victims of Antarctic storms. And where ships land, rats inevitably follow. This led to the destruction of many wild habitats, with little if any hope of recovery. Yet, seemingly against all odds, they were brought back from the very brink of extinction only a few years ago.

By 1993 a conservation program, initiated by the New Zealand government in 1987, had successfully eradicated these feral populations on the Subantarctic Islands. The bird population, having been decimated by rats eating their eggs and young, recovered at an expected rate. However, it was the re-emergence of the Pleurophyllum speciosum, 
by PlantExplorers.com staff illustrator,
William LovegroveMegaherbs that was most remarkable.

Whether these regenerated plants arose from the stunted survivors of excessive grazing, or sprang anew from seed lying dormant for centuries in the cold acidic soil, is still a matter for some research. The results, however, cannot be disputed, as the islands have recovered with vast fields of Megaherbs, growing and blooming in profusion during the short, cold Sub Antarctic summer.

The soil is rich, although very acidic, as the volcanic ash, cool temperatures, and low ambient light have produced thick drifts of moss and lichens over much of the islands. Over aeons the Megaherbs have adapted to these unusual conditions to such a degree that they will not grow well elsewhere. Like so many island populations, the plants of the Subantarctic Islands have developed their unique attributes in isolation, and are now so dependant on the conditions they evolved to suit, that there is little chance of growing these species elsewhere in the world.

Of the many species of Megaherbs endemic to the Subantarctic Islands, three of the most striking are profiled here:

Bulbinella rossii
Ross lily
Named by Hooker in honour of Captain Ross, Bulbinella rossii is one of the few 'Megaherbs' which may be grown in some cool temperate gardens, although bulbs and seeds can be difficult to obtain. The golden flower spikes have been known to reach almost 2m (6ft) in height, but in their native habitat, rarely exceed 1m (3ft).

Pleurophyllum speciosum
Campbell Island Daisy
These plants seemed to have impressed Joseph Hooker the most. After seeing them for the first time, he wrote in his journal;

'...the most extraordinary is the Pleurophyllum meadow, a community dominated by the large-leafed herbaceous composite, producing a floral display second to none outside the tropics.'

The large leaves, like fans of pleated felt, form a rosette of up to 1.25m (4ft) across. The flowers are typical of the daisy family, and have dark maroon almost black centres, with ray petals ranging from almost white to pink or purple.
Its nearest relatives are almost half a world Anisotome latifolia, 
by PlantExplorers.com staff illustrator,
William Lovegroveaway, in South Africa and the Canary Islands, so how its ancient ancestors arrived on the Subantarctic Islands is something of mystery.

Anisotome latifolia
Known as the Campbell Island Carrot, this Megaherb bears only a passing resemblance to its cultivated cousin. The densely packed flower heads can be as much as 50cm (20in) across, and are held up to 1m (3ft) above the feathery foliage on remarkably sturdy stems.

For further information on the recovery of the Subantarctic Islands, or to even join an expedition to see them, there is no better place to start the Department of Conservation - Te Papa Atawhai, New Zealand site.

Next: Sir Joseph Dalton Hooker - The Himalayas

Sir Joseph Dalton Hooker

Sir William Jackson Hooker

For more detailed information on the extraordinary life of Sir Joseph Dalton Hooker...

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