CHILEAN GIANT-RHUBARB

GIANT-RHUBARB

Gunnera tinctoria

Giant-Rhubarb Family [Gunneraceae]

month8jul month8july month8aug month8sep month8sept

status
statusZneophyte
flower
flower8red
inner
inner8green
morph
morph8zygo
petals
petalsZ2
type
typeZspiked
stem
stem8round
stem
stem8hollow
stem
stem8spines
sex
sexZbisexual
sex
sexZmale
sex
sexZfemale

1st July 2005, Muncaster Castle Grounds, Ravenglass. Photo: © RWD
Most specimens are planted in (large) gardens.


27th Sept 2011, Harewood House Pk, Harrowgate, Yorks. Photo: © RWD
An outsize perennial, not a shrub (not woody). Grows up to 1.5metre high.


27th Sept 2011, Harewood House Pk, Harrowgate, Yorks. Photo: © RWD
Mostly planted, grows only in wet places such as by a stream/river/lake etc or on wettish ground.


27th Sept 2011, Harewood House Pk, Harrowgate, Yorks. Photo: © RWD
Very large (up to 2m across) leaves on stalks up to 1.5m high. Looks like a large Rhubarb but is not.


27th Sept 2011, Harewood House Pk, Harrowgate, Yorks. Photo: © RWD
Leaves funnel-shaped, with strong supporting ribs.


27th Sept 2011, Harewood House Pk, Harrowgate, Yorks. Photo: © RWD
Leaves palmately lobed with perhaps 9 lobes.


27th Sept 2011, Harewood House Pk, Harrowgate, Yorks. Photo: © RWD
Net veins.


27th Sept 2011, Harewood House Pk, Harrowgate, Yorks. Photo: © RWD
Unlike Brazilian Giant-Rhubarb, the leaf stems do not have reddish prickles, but greenish ones which are quite flexible.


27th Sept 2011, Harewood House Pk, Harrowgate, Yorks. Photo: © RWD
Stem prickles thorn-shaped, slightly pointing upwards.


27th Sept 2011, Harewood House Pk, Harrowgate, Yorks. Photo: © RWD
Deep underneath the dark canopy of enormous leaves lie the flowering stalk (not shown) and next-years young shoots, which are pinkish-red, tangled into what looks like a nest about 20cm across and reminiscent of a giant Robin's Pincushion. Your Author thinks this is over-winter thermal protection for the developing shoots for next years growth.


27th Sept 2011, Harewood House Pk, Harrowgate, Yorks. Photo: © RWD
Individual new shoots are long, thin, and with many pointed branches.


Not to be semantically confused with : Rhubarb [a plant with similar name]

Easily mis-identified as : Brazilian Giant-Rhubarb, but that is larger still, with leaves often larger than 2m across, and has reddish-tipped bristles and spines on the leaf stems rather than green. The flowering spikes (really upright panicles) of Brazilian Giant-Rhubarb are also longer at up to 1.2m rather than less than 1m.

The large leaves have some similarities in shape to those of Giant Hogweed for which it may be mistaken, but the stems of Giant Hogweed lack the short stubby curved spines. .

The leaves bear some some similarities to those of : Butterbur, but are far larger. Leaf stalks are hollow, but this has no diagnostic value.

It is native to Brazil, but is grown in the UK as a garden plant, mainly for big gardens such as parks, in which setting you are much more likely to see it. When planted in the UK, it does spread a little, but does not behave rampantly like it does in its native country, where it is in places out of control! Little else can take root under the darkness cast by its enormous leaves.

Like Brazilian Giant-Rhubarb the plant produces huge erect catkin-like panicles of flowers, which are usually a mixture of male, female and bisexual flowers. But un-like Brazilian Giant-Rhubarb the panicles are greater than 4 times as long as wide, although their total length at less than 1m long are shorter than those of Brazilian Giant-Rhubarb which are less than 1.2m long.

As the scientific name, tinctoria, suggests, the plant yields a dye, in this case it is the roots from which a black dye can be extracted which was used for dying leather black. The root contains 9% tannin, and it is likely that the black dye is indeed a mixture of tannins.

The roots contain glands that contain a cyanobacterium called Nostoc, which fixes nitrogen for the plant. It is thought to be the only flowering plant in the world which has entered into a symbiotic relationship with a cyanobacterium; all other nitrogen fixing plants rely on eukaryotic bacteria to fix nitrogen rather than prokaryotic bacteria. The plant gives the cyanobacterium carbon compounds in return for soluble nitrogen extracted from the air.

The seed head produces about 80,000 seeds.


  Gunnera tinctoria  ⇐ Global Aspect ⇒ Gunneraceae  

Distribution
 family8Giant-Rhubarb family8Gunneraceae

 BSBI maps
genus8Gunnera
Gunnera
(Giant-Rhubarbs)

CHILEAN GIANT-RHUBARB

GIANT-RHUBARB

Gunnera tinctoria

Giant-Rhubarb Family [Gunneraceae]

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