biology zoology blog benno meyer rochow Pine needles

Pine Needles

Pine needles are not quite as needless as some think: they’re edible!

It’s quite amazing what people can do to turn certain plants or their parts and products into something insipid or savory (note: I am not saying that it has to be delicious). Especially in times of deprivation human inventiveness has produced amazing results, think about acorn coffee or acorn bread, or using the inner bark of birch trees to eat or making deadly poisonous cycad seeds palatable or cooking food with fresh pine tree needles. But why aren’t such kinds of uses more common – at least with regard to human gastronomy? There are after all always some animals that seem to relish what’s pretty awkward to handle digestively by humans.

There can, of course, be mechanical reasons like thorns, difficult shapes and firmness, but more commonly it’s the chemicals in the plants and their parts that cause them to be avoided. Acorns, for instance, contain bitter tasting tannin, a chemical that isn’t exactly poisonous, but whose name relates to the tanning of leather and is certainly not very tasty (to humans). However, many animals love acorns. But then there are the pine needles: they too contain chemicals that aren’t exactly poisonous to humans, but don’t taste too good. Pine oil contains large amounts of terpenes, hydrocarbons that are the characteristic components of rosin and turpentine. On top of that, shape, rigidity and stiffness of pine needles do not make them terribly amenable to swallowing. And yet, there are animals that eat them.

First there are the insects – not really many species actually that feed on pine needles. However, the so-called Spotted Tiger Moth (Halsidota argentata) has caterpillars that love needles and then there are various species of sawflies (actually a group of wasps), whose larvae, looking like caterpillars, can digest the terpenoids and other pine needle oil chemicals. Sawfly larvae, whose visual capacity I studied in 1974 (J. Insect Physiol. 20:1565-1591), are also known to feed on the difficult to digest leaves of eucalypt trees. But how about birds? The old Finnish 10 Markka coin featured a beautiful capercaillie (Tetrao urogallus) a bird that simply loves pine needles. They are its major food and it’s easy to observe how this big bird plucks needle after needle from a pine and swallows them, provided you can close enough to them.

Some mammals, especially those living in pine forests but even goats, too, often feed on pine needles. But do they really like them? Of course one could ask them by letting them choose between different kinds of feed, but the Czech researchers Kamler and Homolka used a different approach to investigate when and how free living herbivores like three kinds of deer and the chamois and the mouflon would turn to pine needles in their diet. The researchers collected the faeces of these animals and examined them for the presence of needles. The researchers found that the presence of needles was a good indicator of food availability in winter. Especially in White-tailed Deer Odocoileus virginianus the amount of pine needles increased as other food sources became scarce or unavailable because of snow coverage and could form up to 90% of their late winter diet. The values for the other species were somewhat lower, but unsurprisingly also much higher in winter than during the summer.

Although pine needles are hard to digest, they do contain valuable nutrients and are rich in vitamin C and I’m now wondering if the information I have given in this little essay might have encouraged some readers to perhaps use their Christmas trees in an unconventional way when the time has come to get rid of them.

© Dr V.B. Meyer-Rochow and http://www.bioforthebiobuff.wordpress.com, 2019.
Unauthorized use and/or duplication of this material without express and written permission from this site’s author and/or owner is strictly prohibited. Excerpts and links may be used, provided that full and clear credit is given to V.B Meyer-Rochow and http://www.bioforthebiobuff.wordpress.com with appropriate and specific direction to the original content.

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