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
spines
sex
sexZbisexual
 
sex
sexZmale
 
sex
sexZfemale
 

1st July 2005, Muncaster Castle Grounds, Ravenglass. Photo: © RWD
Most specimens are planted in (large) gardens. [The bloke is a stranger posing for another photographer, but He'll do for scale].


27th Sept 2011, Harewood House Pk, Harrowgate, Yorks. Photo: © RWD
An outsize perennial, not a shrub (it is 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.


6th Sept 2019, water-feature garden, Lytham St. Annes, Lancs. Photo: © RWD
Planted on all of the several round islands are Chilean Giant-rhubarb. This is the closest your Author could approach without wading (and he doesn't wade, he's not a duck).


6th Sept 2019, water-feature garden, Lytham St. Annes, Lancs. Photo: © RWD
But his zoom camera could reach it. This is an inflorescence which usually consists of an erect pannicle or red-brown flowers - mixture of male, female and bisexual flowers. It is greater than 4 times longer than it is wide, but less than 1m long. They are usually half-hidden beneath the enormous leaves.


6th Sept 2019, water-feature garden, Lytham St. Annes, Lancs. Photo: © RWD
A pannicle of the petal-less flowers. The flowers themselves are the now orange pimples of which there are thousands on any one pannicle.


6th Sept 2019, water-feature garden, Lytham St. Annes, Lancs. Photo: © RWD
Each bullet-shaped green thing (whatever it is called on Gunnera) has many, first green, then orange pimples on it - these are the petal-less flowers.


6th Sept 2019, water-feature garden, Lytham St. Annes, Lancs. Photo: © RWD
This is about the limit of your Authors compact zoom camera. Some of the flowers are still green here, the others matured a bright orange with a teensy bobble at the summit. Yet others have fallen off, presumed ripened into seeds(?) - although only the fertilised female flowers can become viable seeds.


6th Sept 2019, water-feature garden, Lytham St. Annes, Lancs. Photo: © RWD
In amongst the stout bristly stems of the giant leaves lurk a few flowering spikes. Two in this zoom-in.


6th Sept 2019, water-feature garden, Lytham St. Annes, Lancs. Photo: © RWD
One of the (large, heavy) leaves, displaying the stout veins on the underside holding it all up.


6th Sept 2019, water-feature garden, Lytham St. Annes, Lancs. Photo: © RWD
Left: A leaf stem which branches into several very stout veins in order to hold the whole very large heavy leaf.
Right: the teeth of one of the smaller (newer) leaves.


6th Sept 2019, water-feature garden, Lytham St. Annes, Lancs. Photo: © RWD
The stout sharpish bristles on the leaf-stems are angled downwards and are green (on Brazilian Giant-Rhubarb they are red). Presumably the downward angle is to deter the larger animals from attempting to climb up the stems. [A forest of flowers on the right].


6th Sept 2019, water-feature garden, Lytham St. Annes, Lancs. Photo: © RWD
The stout leaf-stems arise from underground rhizomes which enables the plant to spread horizontally and emerge a little further away.


6th Sept 2019, water-feature garden, Lytham St. Annes, Lancs. Photo: © RWD
These leaf stems are without bristles near the ground. A new stem is arising in the centre surrounded by reddish tissues which wither, as on the stems of those around it.


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 pannicles) 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 pannicles of flowers, which are usually a mixture of male, female and bisexual flowers. But un-like Brazilian Giant-Rhubarb the pannicles 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 composed of tannins can be extracted which was used for dying leather black. The root contains 9% tannins.

The roots contain glands that contain a cyanobacterium called Nostoc, which fixes nitrogen from the air 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 (such as those belonging to the Fabacacae family) rely on eukaryotic bacteria to fix nitrogen rather than prokaryotic bacteria. Apart from, that is, Water Fern (Azolla filiculoides) which also fixes nitrogen using Nostoc (plus two other bacteria), except that Water Fern is not a flowering plant. In return for soluble nitrogen extracted from the air Chilean Giant-rhubarb gives the cyanobacterium essential carbon compounds, the symbiosis part of the relationship between the two.

The seed head produces about 80,000 seeds.

Chemically, the BiFlavonoids Morelloflavone and Volkensiflavone have been found in the plant as well as PolyIsoPrenylated BenzoPhenone and 'anthocyanin biflavonoids' (whatever they might be).


  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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