Saturday, 2 October 2010

The day of the gingers

Just a brief interruption on the series on Bristol’s parrots to cover one of the plant collections we have here. Bristol holds two national collections as part of the National Council for the Conservation of Plants and Gardens (now renamed Plant Heritage), which is a gardeners organisation in the UK dedicated to the preservation, conservation, and research on garden plants. As part of its work, Plant Heritage regulates no less than 650 plant collections held by both public bodies like Bristol Zoo or Kew gardens, and also keen amateur gardeners. For more on the NCCPG see the link here:

The two collections Bristol holds are for the ornamental Ginger Lilies Hedychium and the ornamental flowering shrub Caryopteris. The Hedychiums flower from late summer onwards until the first frosts, and visitors will see the end of this seasons display in the next few weeks. This year for the first time we had a stand up at the NCCPG tent at Hampton Court Flower Show (well worth a visit for any gardeners out there) and I am pleased to say we won a medal.

The Ginger family Zingiberaceae is one of the most important groups of food plants other than the staples of rice, wheat and other grains. Many different spices are derived from plants in this family, and in addition the ginger family provides many plants used for medicinal purposes.

Ornamental genera include the shell gingers (Alpinia), Siam or summer tulip (Curcuma alismatifolia), Globba, ginger lily (Hedychium), Kaempferia, torch-ginger Nicolaia, Renealmia, and ginger (Zingiber). Spices include ginger (Zingiber), galangal or Thai ginger (Alpinia galanga and others), melegueta pepper (Aframomum melegueta), myoga (Zingiber mioga), turmeric (Curcuma), cardamom (Amomum, Elettaria).

The various genera include numerous species – there are at least 80 species in the turmeric genus Curcuma for example – and numerous local varieties of the domesticated plants. Many are also harvested from the wild. As well as the roots, the stems and seeds may be used as food, spices, or medicines.

The center of diversity of the ginger family is Asia, with a few genera, notably Aframomum in Africa, and some in Madagascar. A few species are found in the Americas, with one genus, Renealmia, being found in both Africa and South America. DNA studies indicate that Renalmia spread to South America from Africa somewehere between 15 and 2 million years ago. Many members of the ginger family have seeds dispersed by birds, which is probably how they managed to cross the Atlantic.

It is not just humans who eat ginger – various species of Afromomum are important gorilla food plants in West Africa. Human beings use Afromomum plant parts in treatment of inflammation, and also as a cure for internal parasites, and the effect on gorillas is somewhat similar. It is possible that the high levels of anti-inflammatory compounds in the wild diet of gorillas compared to a captive diet may have something to do with the fairly high incidence of inflammatory heart disease in zoo gorillas.

In the Hedychium genus that we have here at Bristol, there are at least 50 species or forms, plus numerous cultivars. Almost all are native to SE Asia, although there is one, H. peregrinum, which is found in Madagascar.

Although in the British climate, Hedychium is an ornamental plant, in the tropics it can become a highly invasive weed. The thick rhizomes forma mat on the forest floor, choking off other vegetation and creating a monoculture of dense foliage. Various means of control include physical removal and herbicides, but these can be hard to administer in all except small areas. Biological control has been considered, but diseases that affect Hedychium are also likely to affect crop plants such as edible ginger, so work is still ongoing. It seems to me the ideal would be to find some animal that gets around easily in dense forest, is physically strong, and likes to eat ginger…

Back to the drawing board

Next week, back to normal with the nectar feeding parrots.

(images from wikipedia and Bristol Zoo website)

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