What smells like almonds in the forest?

April 4, 2016 10:37 AM

While hiking on the Point Reyes peninsula (Marin County, California, USA), we kept smelling an almond smell. We poked and prodded various trees and plants but could not find the source of the smell. What would commonly grow in a costal fir forest that would smell like almonds? It was a strong "so where's the cookies" almond extract-y almond smell, though slightly more herby and piercing than that cheap bakery cookie smell.

If you know the area, we were hiking up Mount Wittenberg, along the trails between Sky Camp trailhead and the top of the hills - Z Ranch Trail, Sky Trail, etc. It's mostly scrubby fir forest and some bishop pine groves. There weren't many mushrooms - and I always look for them. The smell was strongest in the darker forested parts of the trail, not so much on the meadows or exposed portions. It was a clear, chilly day with lots of sun but that cold arctic breeze flowing up from the ocean.

posted by gyusan to Science & Nature (7 answers total)

Best answer: Wow, very cool question, which made me go out and google... which got me to this potential answer: millipedes.
posted by correcaminos at 11:14 AM on April 4, 2016 [11 favorites]

Best answer: A second Point Reyes scent question!

Almonds are part of the Prunus genus. This Point Reyes plant list indicates there's Prunus cerasifera (Cherry Plum) and Prunus ilicifolia ssp. ilicifolia (Holly-leafed Cherry) about the place, but I'm pretty sure correcaminos has it.

From their link:

California’s coast is home to the Yellow spotted millipede that emits a warning smell to predators which smells like almond extract to humans.

posted by zamboni at 11:19 AM on April 4, 2016 [8 favorites]

Doesn't really sound like their habitat, but Jeffrey pines have a pleasant aroma variously described as vanilla or butterscotch, maybe even pineapple, and I don't think almond would be too much of a stretch.. Given where you detected the smell, I'd guess it's either those or a close relative.
posted by LionIndex at 11:20 AM on April 4, 2016

Yes, trees and the fungi that inhabit them make numerous compounds, called VOCs (volatile organic compounds), that are also flavor compounds. I believe benzaldehyde has an almond flavor. Trees and fungi in the forest both make that!
posted by Kalmya at 11:27 AM on April 4, 2016 [2 favorites]

Best answer: a warning smell to predators which smells like almond extract to humans.

It smells like bitter almonds because the tiny caterpillar is exuding toxic hydrogen cyanide/prussic acid.

Caterpillar: AAAH! THREAT! I KILL YOU! I KILL YOU!
Human: Mmmm, does anyone smell cookies?
posted by zamboni at 11:39 AM on April 4, 2016 [60 favorites]

Response by poster: hah - millipedes? We did see several - perhaps 2 inches long, thick shiny black ones... that would be crazy if that was the smell. Would one really be able to smell wafts of millipede cyanide as you walked along?

Not really cherry plum habitat; we were up on top of inverness ridge. The area is mostly Fir and dense stands of Bishop Pine. As for Jeffrey pine - I know their butterscotch/pineapple smell well and this was't it.

We spent some time sniffing the new growth on trees, and breaking leaves from the various plants along the trail in an attempt to find the source, but I never thought to sniff a millipede...
posted by gyusan at 12:17 PM on April 4, 2016

Caterpillar:

and by caterpillar, I mean millipede. Heh.
posted by zamboni at 12:49 PM on April 4, 2016 [4 favorites]