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Article on broom and gorse


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A recent trip to Taupo served to jog the memory of how common the broom plant is in that region.

In Taranaki, we have loads of gorse but not much broom, with the latter probably the more acceptable of the two because of the absence of sharp spines.

They look quite similar, both have very thin, very dark green stems capable of photosynthesising, thus making plant food from the sun, which most plants do with their leaves. But the leaves on both gorse and broom are very temporary and it's the stems that do the work.

Both are capable of surviving droughts and poor soil. In part they can do this because they are legumes, so they can make their own nitrogen fertiliser from the atmosphere. In other words they're cheap to keep and in fact it's like planting a crop of lupin in your vege garden to enrich the soil.

Growing broom or gorse improves the fertility and the structure of the soil. A dense clay soil with poor drainage will be enriched by a crop of either gorse or broom resulting in a more open friable topsoil.

When they die and break down, the wood quickly rots and adds a layer of organic matter, plus their roots penetrate deeply leaving channels for the water to run once the plant has died. And die they will because they are short-lived, growing incredibly fast for the first two years and maybe living to between five and 10 before they run out of steam and fade away.

Even the ornamental brooms we buy in garden centres are very short lived, though we can extend their life by pruning at the right time of the year. If you prune the recent growth back by half or even two thirds after the bush has finished flowering you will extend the life because you're reinvigorating it and also reducing the height, so somehow the plant is tricked into thinking it hasn't reached maturity. They're good hardy plants but, because of the weed association, they're not very popular these days. But if you live in a windy site, they can be good value as an evergreen with showy flowers.

We call them Cytisus scoparius or brooms and this fits with the notion of making sweeping or witches' brooms from the strong straight stems; scoparius means to sweep. The broom plants have beautiful fragrant flowers and while the common sort is bright yellow, the cultivars vary from white to pale yellow and orange through to rich reds and even bicolours. One additional benefit of growing brooms is the little known fact that the flowers make a powerful wine. Years ago I was persuaded to pick broom flowers for wine making. I relished the ease with which this thornless bush could be stripped of its flowers compared to the spiny gorse that can also be used to make wine. The resulting brew of broom was so heady you only had to remove the cork to get dizzy. One small wine glass had you retreating to a darkened room to recover. You've heard the expression - don't try this at home. Well it certainly applies in this case.

Broom's sweep in world | Stuff.co.nz

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Hmmm. There is speculation that these nitrogen fixing legumes en mass are responsible, partly, for increased nitrate levels in water ways. Particularly if the plantation is on hilly slopes above streams

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Glyn Church has obviously never seen old man gorse. Oh how I wish the stuff did die off in 10 years!

It does thrive on poor clay soils like ours but it also leaves behind a seed bank that lasts 80 years or more.

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If they are fixing nitrogen, surely they are keeping it out of the waterways?
The nitrogen fixing bacteria, which live in a symbiotic relationship with legumes, 'fix' nitrogen from the atmosphere. 'Fix' means they convert it from atmospheric nitrogen into ammonia, which is then available for the host plant to use. The thing is, is that ammonia is produced in excess, and while some used by the plant, some is lost to the atmosphere and some is stored in the soil, much is susceptible to runoff with rainfall, and ends up in the waterways as nitrates
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Interesting, looks like its a good pollen source without the spikes of gorse, I might have to track some down for our Bush block.

 

 

Anyone deliberately spreading exotic broom obviously is unaware of it's south Island status as pastoral Enemy Number One. Millions of dollars are spent annually by govt, local authorities, and landowners on keeping it in check. Note "keeping it in check" not eradicating

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The thing about broom is that sheep will eat it down, where they just trim gorse into umbrella shapes. And broom doesn't hurt you when you walk through patches of it. Otherwise it's just as much of a pest.

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The nitrogen fixing bacteria, which live in a symbiotic relationship with legumes, 'fix' nitrogen from the atmosphere. 'Fix' means they convert it from atmospheric nitrogen into ammonia,
Actually its a bit more complicated than that and involves ammonium and nitrates and microbes and soil pH, but that's the simplistic view of the nitrogen cycle as I understand it.
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Actually its a bit more complicated than that and involves ammonium and nitrates and microbes and soil pH, but that's the simplistic view of the nitrogen cycle as I understand it.

I know there are root nodules involved somewhere.

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Anyone deliberately spreading exotic broom obviously is unaware of it's south Island status as pastoral Enemy Number One. Millions of dollars are spent annually by govt, local authorities, and landowners on keeping it in check. Note "keeping it in check" not eradicating

 

Your probably right, I should just leave the Bees to collect the pollen on all the gorse and Broom on council land around Auckland, it's only frowned upon when it's on private land up here, council obviously has a special dispensation .....

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