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Nettling conundrum
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THE LAST WORD Nettling conundrum
to how much carbon such storage could accumulate. Its only rivals for sheer magnitude would be the deep-sea accumulation of dissolved CO2, and carbonate minerals and soils in places such as chalk cliffs and downs. Jon Richfield Somerset West, South Africa
Can any readers identify this object (see photo) growing on a stinging nettle of the species Urtica dioica? The nettle was beside a gravel drive, and there are some small patches on the underside of the leaf ribs.
n Such orange-red swellings on the stinging nettle’s stem, which tend to cause it to curve, are the result of an infection by the fungus Puccinia caricina. Small orange cusps are found on the surface of these deformations, or galls. These contain one of the several different types of spore that this fungus produces. Puccinia is a representative of the group of fungi known as rusts. But in contrast with fungi such as mushrooms, which feed on dead or decaying organic material, rusts infect living plants and are known as obligate parasites – organisms that cannot complete their life cycle without exploiting a suitable host. Members of the rusts cause diseases in many cereal crops, and have extremely complex life
“Members of the rusts cause diseases of cereal crops and have extremely complex life cycles”
This week’s questions Dinosaur DNA
galls on the leaves and berries of the redcurrant. Frank Wuytack Herent, Belgium
Waning woodpile Sometimes the wood at the bottom of our woodpile decays to the point where it has only a small fraction of its previous dry mass. What has happened to it? Where did all the carbon go? From the point of view of greenhouse gas emissions, is it better for the wood to be burned in my fire or for it all to rot back into the earth?
cycles that often involve different host species. In the case of P. caricina, another host in addition to stinging nettles is the grass-like sedge plant, and it also forms
n Dead wood is first converted into living biomass, mainly through the actions of fungi, other microbes and woodlice. Eventually, it ends up as carbon dioxide, methane, water and
The writers of answers that are published in the magazine will receive a cheque for £25 (or US$ equivalent). Answers should be concise. We reserve the right to edit items for clarity and style. Please include a daytime telephone number and an email address if you have one. New Scientist retains total editorial control over the published content. Reed Business Information Ltd reserves all rights to reuse all question and answer material that has been
submitted by readers in any medium or in any format and at any time in the future. Send questions and answers to The Last Word, New Scientist, 110 High Holborn, London WC1V 6EU, UK, by email to [email protected] or visit www.newscientist.com/topic/lastword (please include a postal address in order to receive payment for answers). Unanswered questions can also be found at this URL.
nitrogen, plus minor quantities of mineral solids, most of which eventually wash away or remain in the soil as fertiliser. However, in terms of greenhouse gas emissions, rotting offers advantages despite its release of methane. Fire abruptly converts almost all the carbon into CO2, whereas detritus feeders and agents of decay leave some combustible materials, such as lignin and humic acids, that act as buffer stores for carbon. Those stores last for years, accumulating in the soil as solids rather than in the air as CO2. It would take the CO2 from burning a long time to settle down innocuously like the trapped residues produced by the wood rotting. There is no simple global limit
I recently watched the movie Jurassic Park and its sequels, in which DNA from the stomachs of mosquitoes stuck in amber was used to recreate the dinosaurs. Could you do this in real life? Joseph Scott (age 10) Stonehaven, Aberdeenshire, UK Upright snooze
Why do some animals, such as humans, lie down to sleep, whereas others, such as elephants and giraffes, stand? Martie van der Walt Pretoria, South Africa A bed of rocks
Railway sleepers often sit on a bed of small stones that act as ballast. This ballast material stretches well beyond the width of the sleepers and to quite a depth. But why does it have to be stones? Could anything else be used either physically or economically? Peter Brigg Queensland, Australia
Question Everything The latest book of science questions: unpredictable and entertaining. Expect the unexpected Available from booksellers and at newscientist.com/questioneverything
THE LAST WORD Nettling conundrum
to how much carbon such storage could accumulate. Its only rivals for sheer magnitude would be the deep-sea accumulation of dissolved CO2, and carbonate minerals and soils in places such as chalk cliffs and downs. Jon Richfield Somerset West, South Africa
Can any readers identify this object (see photo) growing on a stinging nettle of the species Urtica dioica? The nettle was beside a gravel drive, and there are some small patches on the underside of the leaf ribs.
n Such orange-red swellings on the stinging nettle’s stem, which tend to cause it to curve, are the result of an infection by the fungus Puccinia caricina. Small orange cusps are found on the surface of these deformations, or galls. These contain one of the several different types of spore that this fungus produces. Puccinia is a representative of the group of fungi known as rusts. But in contrast with fungi such as mushrooms, which feed on dead or decaying organic material, rusts infect living plants and are known as obligate parasites – organisms that cannot complete their life cycle without exploiting a suitable host. Members of the rusts cause diseases in many cereal crops, and have extremely complex life
“Members of the rusts cause diseases of cereal crops and have extremely complex life cycles”
This week’s questions Dinosaur DNA
galls on the leaves and berries of the redcurrant. Frank Wuytack Herent, Belgium
Waning woodpile Sometimes the wood at the bottom of our woodpile decays to the point where it has only a small fraction of its previous dry mass. What has happened to it? Where did all the carbon go? From the point of view of greenhouse gas emissions, is it better for the wood to be burned in my fire or for it all to rot back into the earth?
cycles that often involve different host species. In the case of P. caricina, another host in addition to stinging nettles is the grass-like sedge plant, and it also forms
n Dead wood is first converted into living biomass, mainly through the actions of fungi, other microbes and woodlice. Eventually, it ends up as carbon dioxide, methane, water and
The writers of answers that are published in the magazine will receive a cheque for £25 (or US$ equivalent). Answers should be concise. We reserve the right to edit items for clarity and style. Please include a daytime telephone number and an email address if you have one. New Scientist retains total editorial control over the published content. Reed Business Information Ltd reserves all rights to reuse all question and answer material that has been
submitted by readers in any medium or in any format and at any time in the future. Send questions and answers to The Last Word, New Scientist, 110 High Holborn, London WC1V 6EU, UK, by email to [email protected] or visit www.newscientist.com/topic/lastword (please include a postal address in order to receive payment for answers). Unanswered questions can also be found at this URL.
nitrogen, plus minor quantities of mineral solids, most of which eventually wash away or remain in the soil as fertiliser. However, in terms of greenhouse gas emissions, rotting offers advantages despite its release of methane. Fire abruptly converts almost all the carbon into CO2, whereas detritus feeders and agents of decay leave some combustible materials, such as lignin and humic acids, that act as buffer stores for carbon. Those stores last for years, accumulating in the soil as solids rather than in the air as CO2. It would take the CO2 from burning a long time to settle down innocuously like the trapped residues produced by the wood rotting. There is no simple global limit
I recently watched the movie Jurassic Park and its sequels, in which DNA from the stomachs of mosquitoes stuck in amber was used to recreate the dinosaurs. Could you do this in real life? Joseph Scott (age 10) Stonehaven, Aberdeenshire, UK Upright snooze
Why do some animals, such as humans, lie down to sleep, whereas others, such as elephants and giraffes, stand? Martie van der Walt Pretoria, South Africa A bed of rocks
Railway sleepers often sit on a bed of small stones that act as ballast. This ballast material stretches well beyond the width of the sleepers and to quite a depth. But why does it have to be stones? Could anything else be used either physically or economically? Peter Brigg Queensland, Australia
Question Everything The latest book of science questions: unpredictable and entertaining. Expect the unexpected Available from booksellers and at newscientist.com/questioneverything