Saturday, September 4, 2010

Highbush Cranberry--Viburnum trilobum vs. Viburnum opulus


I first spotted them while running down highway five, a brilliant splash of scarlet amidst the tangle of green shrubs on the roadside. I'd never identified a highbush cranberry before, but I knew them when I saw them. It is a strange and wonderful thing that happens when you spend enough time reading field guides and dreaming about the plants in them. I think people who seem to develop a sixth sense about something must all do it this way. They spend so much time learning about, imagining, and telling the stories of the things that they are passionate about that eventually they know something without even knowing how they know it. I knew it was a highbush cranberry. I don't know how. I just knew.


Today, we stopped by the shrub for a closer look. There are several species which share the same common name, one of which is not truly palatable. Which one was this?


Sometimes field guides use differences of degree to differentiated species. They will state that one species is taller, pointier, greener, thicker, or more flattened than another. I find this useful when I am already familiar with one of the plants that's being compared. But I find it frustrating when I've never seen either plant in person before. That was the case here. My field guide said that Viburnum opulus, the species that I wanted to avoid, had "smaller, wider, more dentate leaves, and thinner, darker twigs" than Viburnum trilobum, the species I wanted to eat. It was not much help.


Well, I knew what genus it was in, and I'd narrowed it down to two possibilities. Neither would kill me. "I might as well just try a berry," I thought. I did. It was sour. It had the distinct flavor that all viburnums share which I can only describe as being akin to the sweet and not unpleasant smell of newly rotting apples. And it was quite bitter. I spit it out and looked back at my guide. Yup, that was V. opulus all right. We won't be adding that to our list.

3 comments:

  1. PS. Highbush cranberry is not a close relative of the bog-dwelling plant whose sauce graces your Thanksgiving table. True cranberries are in the genus Vaccinium and are more closely related to blueberries than they are to the viburnums whose fruit look and taste so much alike.

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  2. I think I may have found something to aid you in telling trilobum and opulus apart in the field. Going by this source: http://plantfacts.osu.edu/pdf/0247-1153.pdf
    both species have warty glands on the petiole at the base of the leaf. In opulus, these glands are sessile and concave, while in trilobum, they are convex and slightly stalked. You may need a hand lens to view these. Hope that helps!

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  3. http://plants.usda.gov/factsheet/pdf/fs_viopa2.pdf

    Opulus and tribolum may be the same plant according to this

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