Download . Brazilian Giant Rhubarb, Gunnera manicata Overview Overview

Brazilian Giant Rhubarb, G u n n e r a m a n i c a t a
Overview
.
Short description of G u n n e r a m a n i c a t a, Brazilian Giant Rhubarb
It is a giant clump-forming perennial herb which can grow up to 3m in height and 4m
across. It has deep green, round to kidney-shaped palmately lobed leaves which can reach
2.5m long and 2m wide arising from a stout scaly rhizome. The leaf stalks bear short reddish
bristles and spines. Minute green or rusty-red flowers are borne on erect, cone-like
compound inflorescences up to 1.2 m long, followed by hundreds of densely packed small
red-green rounded fruits.
Description of G u n n e r a m a n i c a t a, Brazilian Giant Rhubarb status in GB
Brazilian Giant-rhubarb is a popular garden ornamental that has become naturalised in
scattered locations in lowland GB. It is cast out of gardens and appears to be spreading
slowly.
H a b i t a t s u m m a r y : G u n n e r a m a n i c a t a, Brazilian Giant Rhubarb
Found in sheltered areas where the ground is permanently moist, such as lake margins and
streamsides.
Overview table
Environment:
Terrestrial
Species status:
Non-Native
Native range:
Brazil
Functional type:
Land plant
Status in
England:
Non-Native
Status in
Scotland:
Non-Native
Status in Wales:
Non-Native
Location of first
record:
v.c.35
Date of first
record:
1935
GB Distribution from N B N G a t e w a y
Author's name:
Sharon Pilkington
Last updated:
August 8th, 2011
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up to date, however if you notice
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Invasion history: G u n n e r a m a n i c a t a, Brazilian Giant
Rhubarb
Origin
It is a native of Brazil.
First Record
It was probably first recorded from the wild in 1935. The reliability of some records may be
doubtful as there has been confusion in the past between true G. manicata and closely
related species including G. morae and G. tinctoria.
Pathway and Method
First introduced as a garden ornamental in 1867, it has since been widely promoted as an
architectural herb for planting around ponds and in damp areas and has been awarded an
Award of Garden Merit by the Royal Horticultural Society. However, its enormous size means
that it quickly outgrows all but the largest gardens and estates.
Species Status
Much less common and more widely scattered than Giant-rhubarb G. tinctoria, this plant is
considered by Stace (2010) to be ‘scarcely naturalised but persistent’ in GB. By 1999 it had
been recorded in 45 10 km grid squares in the British Isles, two-thirds of these sightings
between 1987 and 1999, suggesting that it is spreading slowly. Unlike G. tinctoria, Brazilian
Giant-rhubarb does not set viable seed in GB and its invasiveness is unconfirmed. It is also
naturalised in Australia, New Zealand, Germany and Switzerland.
Ecology & Habitat: G u n n e r a m a n i c a t a, Brazilian Giant
Rhubarb
Dispersal Mechanisms
Because of their large size, plants are often dug up and cast out of gardens where they
regenerate from fragments of rhizome, although the rate of vegetative spread is slow.
Although its seeds are eaten and dispersed by birds, it does not appear to germinate in GB.
Reproduction
Between June and August, Brazilian Giant-rhubarb bears large numbers of tiny flowers on
large cone-shaped inflorescences which are wind-pollinated. Large numbers of small, slightly
fleshy fruits containing a single seed follow and mature in the autumn. Each seedhead can
produce in excess of 80,000 seeds but so far, British seed does not appear to be viable under
natural conditions.
Known Predators/Herbivores
It has no significant predators or herbivores.
Resistant Stages
In winter, leaves die back to expose thick brown scaly rhizomes which are capable of
producing new plants if detached from the parent and which bear massive over-wintering
buds. It is not known how long detached pieces of rhizome can survive.
Habitat Occupied in GB
Brazilian Giant-rhubarb prefers lowland habitats offering shelter and wet ground, typically in
the vicinity of lakes and watercourses and in woodland.
Distribution: G u n n e r a m a n i c a t a, Brazilian Giant
Rhubarb
Most populations occur in southern England, where it is most frequent along the south coast
from Dorset to Cornwall. It is very rare in Wales, northern England and Scotland and absent
from Ireland.
I m p a c t s : G u n n e r a m a n i c a t a, Brazilian Giant Rhubarb
Environmental Impact
The enormous leaves of the plant prevent other species from growing beneath them and
colonies can suppress natural biodiversity and alter ecosystems. In GB it does not appear to
develop the extensive and dense stands of G. tinctoria. However, the plant has a symbiotic
relationship with nitrogen-fixing cyanobacteria and this may confer an advantage to young
plants growing in nitrogen-deficient soils.
Health and Social Impact
In summer the large size of the plants is often visually disjunct with the surrounding
vegetation. In winter, the large prostrate brown rhizomes are exposed and look unsightly
and this is compounded when they trap litter.
Economic Impact
Brazilian Giant-rhubarb can block drains and streams, increasing the risk of local flooding
when water levels are high. It can be quite very difficult and costly to eradicate and may be
an economic burden to landowners and organisations charged with its management.
References & Links: G u n n e r a m a n i c a t a, Brazilian Giant
Rhubarb
Identification
Stace, C.A. (2010) New flora of the British Isles, Third Edition, Cambridge University Press,
Cambridge.
Wanntorp, L., Wanntorp, H.-E. & Kallersjo, M. (2002) The Identity of Gunnera manicata
Linden ex Andre – resolving a Brazilian-Colombian enigma. Taxon, 5 1, 493-497.
Wanntorp, L. & Klackenberg, J. (2006) Gunnera morae (Gunneraceae), a new species from
Colombia. Caldasia, 2 8 ( 2 ), 221-225.
Biology, ecology, spread, vectors
Distribution maps from the NBN Gateway:
www.searchnbn.net/searchengine/search.jsp?tab=1&pg=1&searchTerm=Gunnera+manicata
Global Invasive Species Database: www.invasivespecies.net/database/species
Management and impact
Global Invasive Species Database: www.invasivespecies.net/database/species
General
Factsheet about Giant-rhubarbs Gunnera species by GB non-native species secretariat:
www.nonnativespecies.org
Preston, C.D., Pearman, D.A. & Dines, T.D. (2002) New Atlas of the British and Irish Flora,
Oxford University Press, Oxford.