The family Aceraceae consists of over 150 species of some of the most beautiful and diverse trees and shrubs, with Acer pentaphyllum standing out from the rest of the crowd.
Adventurous history
Joseph Rock originally brought Acer pentaphyllum into cultivation in 1929, after an expedition to southwestern Sichuan, China.
Only three trees survived in cultivation from this collection at Strybing Arboretum in San Francisco. Unfortunately all three had died by 1991, with one of them being killed by squirrels removing all the bark.
Fortunately, several nurseries in North America had propagated the trees through grafting, as these trees produced little viable seed.
These subsequent plants produced viable seed and almost all Acer pentaphyllum in cultivation today can be traced back to the original trees at Strybing Arboretum, and thus to Rock's original collection.
Cultivation
Acer pentaphyllum has wonderful fine, five-lobed leaves which turn amazing shades of orange and yellow in autumn. It is best suited to a sheltered location with plenty of summer moisture but a free-draining soil so the roots don't get waterlogged in winter.
Fast-growing as a young plant, it does slow down as it matures, reaching only 3m to 4m after 10 years.
Lucky escape
Luckily, in New Zealand we have at least one tree that sets viable seed and many seedlings are grown commercially and are available in garden centres.
In the wild there are three known populations with fewer than 200 individuals.
These are in remote areas of western Sichuan where local farmers have a subsistence living, using any trees around them as valuable firewood.
This puts great strain on the future survival of Acer pentaphyllum in the wild and emphasises the importance of botanic gardens and horticulturists keen to grow these unusual plants.
Acer pentaphyllum can be seen in the geographic collection at Dunedin Botanic Garden. - By Dylan Norfield
- Dylan Norfield is the Geographic Collection Curator at Dunedin Botanic Gardens
