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BROOM

SCOTCH BROOM

Cytisus scoparius

Pea Family [Fabaceae]

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category
category8Deciduous
 
category
category8Broadleaf
 
status
statusZnative
 
flower
flower8bicolour
 
flower
flower8yellow
 
inner
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morph
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petals
petalsZ5
 
stem
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stem
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fluted
toxicity
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BROOM

(Cytisus Scoparius ssp. scoparius)

12th June 2009, Greenside Mines, Glenridding, Cumbria. Photo: © RWD
Colonising the valley.


11th June 2010, Greenside Mines, Glenridding, Cumbria. Photo: © RWD
A shrub up to 2 metres tall, with yellow flowers (sometimes yellow with red).


12th June 2009, Greenside Mines, Glenridding, Cumbria. Photo: © RWD
A young plant by moss. A mass of narrow branched twigs with small leaves close to the stems. Hawkweed in background.


8th May 2009, Coppermines Valley, Coniston, Cumbria. Photo: © RWD
The twigs have flowers in pairs emerging from a triplet of leaves along the stems.


11th June 2010, Greenside Mines, Glenridding, Cumbria. Photo: © RWD
The pea-type flowers are bi-symmetric with long stamens and anthers with yellow pollen.


11th June 2010, Greenside Mines, Glenridding, Cumbria. Photo: © RWD
Flowers either wholly yellow, or with red splotches.


11th June 2010, Greenside Mines, Glenridding, Cumbria. Photo: © RWD
Pronounced red splotches on the wings look like they have been air-brushed on.


9th June 2009, Blackleach Resr, Gtr M/cr. Photo: © RWD
Pods beginning to grow. Some remains of the flowers still visible at each end of the developing pods.


9th June 2009, Blackleach Resr, Gtr M/cr. Photo: © RWD
The green seed-pods grow with remnants of stigma still attached at the end.


9th June 2009, Blackleach Resr, Gtr M/cr. Photo: © RWD
The seed-pods are flat and hairy, and contain many seeds in rows just like (flat) peas in a pod.


29th June 2009, Nob End, Ringley, Gtr M/cr. Photo: © RWD
The green hairy pod with four obvious seeds within. The hairs are mostly on the edges rather than the sides of the pod.


5th Aug 2008, Woodvale Woods, Ainsdale, Lancs. Photo: © RWD
Pods turn black when ripe. This one has many more seeds.


29th June 2009, Nob End, Ringley, Gtr M/cr. Photo: © RWD
The leaves are in triplets close to the five-sided fluted stem. [Spanish Broom has ten sides].


29th June 2009, Nob End, Ringley, Gtr M/cr. Photo: © RWD
The stems have 5 sides. The knobs are where the leaves and flowers and then pods once were.


11th June 2010, Greenside Mines, Glenridding, Cumbria. Photo: © RWD
A yellow with red variant.


23rd June 2015, waste ground, Moore, Warrington, Lancs. Photo: © RWD
Perhaps atypical in stance and perhaps even a cultivated form(?), but conforming to form in that most flowers have turned to seed pods before Midsummers Day, (which, as everyone should know is on the 24th June, and certainly not on the 21st or sometimes the 22nd June which is the Summer Solstice). It is surrounded by the non-native Shasta Daisy (Leucanthemum × superbum), which is perhaps another reason to doubt that this specimen is native. However, many other Brooms like this were growing in the same area.


23rd June 2015, waste ground, Moore, Warrington, Lancs. Photo: © RWD
The seed pods of the above colony look typical for the native Broom.


23rd June 2015, waste ground, Moore, Warrington, Lancs. Photo: © RWD
As do the small leaves. Showing how they join to the stem, which also looks normal.


PROSTRATE BROOM

(Cytisus Scoparius ssp. maritimus)

Sorry, no photos as of yet.


Not to be confused with : Spanish Broom (Spartium junceum) [which is more poisonous but has round stems rather than 5-angled, deeper yellow flowers and leaves that are never trefoil and seed pods that are hairy all-around],

Broom exists as one of two sub-species :

  • Prostrate Broom (Cytisus Scoparius ssp. maritimus) which is a low-lying plant that often grows near the sea, but that is restricted to the far west coasts of Wales and Devon & Cornwall.
  • Broom (Cytisus Scoparius ssp. scoparius), which is much more widespread than Prostrate Broom.
The above photographs are of the ssp. scoparius since they are not prostrate.

Uniquely identifiable characteristics

Distinguishing Feature : a shrub with thin fluted 5-angled stems, and yellow or yellow & orange pea-type flowers.

No relation to : Broomrapes such as Common Broomrape (Orobanche minor) nor to Butcher's Broom (Ruscus aculeatus) [plants with similar names belonging to differing families].

Broom, gathered in bunches, was once used to sweep the floor, hence the name of 'broom' for this kind of brush. It has also been used as a source of fibre and can be made into both paper and cloth. The wood of Broom was once highly acclaimed for use in furniture as a veneer. Broom twigs have been used in basket-weaving. Like a great many other things, Broom was also added to beer as the bitter component instead of Hops, and the ground seeds once used as a 'coffee', although it must have caused some distress because of the constituent poisonous alkaloids.

Whereas Broom has five-sided fluted stems, Spanish Broom has ten, and this is the main difference between them. Broom has either wholly yellow or yellow with red flowers. It spreads by seeds which are flung up to 10 feet out of the seed pods. It is also bird-sown.

It can be confused with garden varieties specially bred to enhance the two-tone colour aspect. Unlike Broom itself which stops flowering after June, these cultivars flower from June to September, rather than April to June of a true Broom. The cultivars can also be readily bird-sown.

Scotch Broom (or just Broom) is of only low toxicity. In particular, it contains no Cytisine unlike Spanish Broom. But it does contain other toxic alkaloids, amongst them l-Sparteine (up to 0.22% in the flowers, and over 1.5% in other parts of the plant) plus Sarothamnine (possibly now called iso-Sparteine), Genisteine, Lupanine and Oxysparteine. The yellow pigmented flavone glycoside Scoparoside now better known as Scoparin has been found in both the leaves and branches of this plant. Another flavone glycoside, Vitexin is also present, which is the glycoside of the flavone Apigenin.

AN ISOFLAVONE

The isoflavone Genisteine, which despite many pages to the contrary on the internet, is not an alkaloid!. Isoflavones are secondary metabolites of members of the Pea Family and many exhibit phyto-oestrogenic activity, mimicking the female mammalian sex hormone (oestrogen). Some other isoflavones are induced in plants after infection by pathogens, and behave as phytoalexins (chemical deterrents for plants). Note that Genisteine is an isomer of Apigenin, shown below. One is a flavone, the other an isoflavone.

It is hoped that Genisteine may prove useful to treat a rare brain disease called Sanfilippo which aflicts youngsters who usually die of the condition before their 15th birthday. There is otherwise no cure for the fatal condition. The brains of youngsters with the condition are unable to process the glucose the brain requires and which is transported there in the bloodstream. The brains of such youngsters are deficient in one of the four enzymes involved in the lysomal degradation of glycosaminoglycan heparan sulfate, which otherwise accumulates to dangerous proportions. There are four diseases in the sanfilippo syndrome group, each corresponding to a deficiency in each of the four enzymes.

FLAVONE GLYCOSIDES

The yellow pigmented flavone glycoside Scoparoside now better known as Scoparin has been found in both the leaves and branches of this plant.

Another flavone glycoside, Vitexin is also present, which is the glycoside of the flavone Apigenin. Vitexin possesses pharmacological properties such as being an anti-histamine, anti-serotonin and anti-bradykinin. It may find use as an anti-inflammatory, a potent hypotensive and an anti-spasmodic.

The two flavone glycosides differ only in a methoxy group on the flavone. Another flavonol glycoside present is that of the 4'-O-Glycoside of Quercetin called Spiraeoside, which was also found in Meadowsweet, from which it derives its name (Meadowseeet used to have the scientific name Spiraea ulmaria until it was changed to Filipendula ulmaria. Unfortunately, the name of the secondary metabolite did not follow suit~).


Note that Apigenin is an isomer of Genisteine, shown above. One is a flavone, the other an iso-flavone. Apigenin is the aglycone (without a sugar) of several different glycosides of Apigenin. It is responsible for the cancer prevention characteristics of several vegetables and fruits. It puts mammalian cells into autophagia, a kind of protective dormancy. Apigenin is a potent inhibitor of an enzyme responsible for the metabolization of many pharmaceutical drugs within the human body, so should be regarded with care. It also induces resistance against chemotherapy.

OxySparteine is Sparteine (a lupanane alkaloid) with an added ketonic oxygen atom. Sparteine has the effect of restoring a feeble irregular heartbeat back to normal, particularly useful for stubborn cases of arterial fibrillation. The chemically related Oxysparteine, Anagyrine and Lupanine have similar actions. Note that if it wasn't for the single ketone group (=O), then OxySparteine would be a dimer; indeed, Sparteine itself is a dimer.

CYTISINE


Cytisine (not to be confused with the amino acid Cysteine) is an alkaloid with two nitrogen atoms and three fused pyridine-type rings, one sharing the same nitrogen atom, forming three six-membered (albeit fused) rings. Shown above are two possible ways of depicting it pictorially, with the second diagram more clearly showing its relationship to Oxysparteine above. It is found naturally in many members of the Faboideae Family (which is a sub-family of the Pea Family (Fabaceae)) including Anagyris, Cytisus, Genista, Laburnum, Thermopsis and the non-native Sophora as well as in some trees that are not native to the UK.

Cytisine is poisonous to humans, but possibly not to sheep or goats. Some caterpillars are able to sequester the toxin where it is deployed against predators. Such caterpillars usually have conspicuous aposematic colouring to warn predators of their poisonous nature, after all, the purpose is to avoid being eaten rather than to kill predators and die doing so, but some will inevitably succumb which helps revitalise the poisonous legend.

Cytisine binds to and blocks the same nicotinic acetylcholine receptors to which Nicotine binds and activates. It is therefore used as a drug to help tobacco addicts quit smoking. It mimics some of the effects of Nicotine, which is shown below for comparison only - Nicotine is not found in Broom.



A synthetic derivative of Cytisine called Varenicline (shown alongside) is more widely prescribed to help quit smoking and is used in skin-patches. As far as is known, Varenicline does not occur naturally and is an alkaloid containing three nitrogen atoms and four fused rings of 6, 6, 5 and 6 members, respectively.


  Cytisus scoparius  ⇐ Global Aspect ⇒ Fabaceae  

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BROOM

SCOTCH BROOM

Cytisus scoparius

Pea Family [Fabaceae]

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