It’s been a great growing season on PEI, and our fall fruits are showing the result. Wild berries are everywhere right now, including the colourful Highbush Cranberry (Viburnum opulus).
Despite the name, Highbush Cranberry is not at all related to the traditional Thanksgiving dinner condiment. It is in the same family as Elderberries (Sambucus spp.) and the same genus as the Wild Raisin (Viburnum cassinoides) I posted about on September 12. This time of year, Highbush Cranberry’s bright red fruit and rust-coloured leaves stand out in the landscape (Photo 1).
Edible and palatable are two very different things. Raw Highbush Cranberries are amazingly juicy, but have a hard pit and sour, bitter, musky taste – I encourage you to try one to see what I mean! This is not a fruit most people would volunteer to eat in quantity, which is probably just as well: there have been reports of raw Highbush Cranberries causing intestinal upset in those who ate too many. (Though in fairness, eating too much of any new-to-you food can have the same effect).
If the flavour of the raw berries isn’t enough to put you off, their smell might: think of old gym bag with a touch of dirty sock thrown in. Amazingly, at some point someone dared try this bad-tasting, foul-smelling fruit cooked and sweetened, and found that it makes delicious sauces and jellies. The catch is that the smell permeates whatever you are making (and your house while you are cooking it), but if you can get past that the flavour is very good. Some Highbush Cranberries have fruit that smells worse than others (more on this in a moment), so crushing and smelling a few berries as you go can help you forage from less pungent plants.
When not in fruit, Highbush Cranberry can be easily identified by its three-lobed leaves (Photo 1), and distinctive flowers that appear in June (Photo 2). Those flowers are deceptive! What look like showy, five-petalled, white flowers around the outside are actually sterile decorations just there to attract insects. The true flowers are tiny and in the centre of the flower head.
If you noticed that the leaves and sterile flowers of Highbush Cranberry look a lot like the cultivated Snowball Bush, give yourself a gold star! Hundreds of years ago, horticulturalists developed a variety of this shrub with round, decorative clusters of those sterile flowers and no true flowers. It’s the same genus and species as Highbush Cranberry and remains a popular ornamental.
Its history of cultivation makes Highbush Cranberry is one of our more confusing plants: there are both native and European varieties on the Island and they can be tricky to tell apart. In my experience, the non-native Viburnum opulus var. opulus is much more common, but the native Viburnum opulus var. americanum has better flavour and less of that off-putting smell.
Telling them apart requires a close look at the leaf stem (Photo 3). Both varieties have glands that look like green dots on the reddish stem. In the non-native variety (shown here), those glands are bowl-shaped with a distinctive rim around the outer edge; the glands of native plants are taller and flat-topped or rounded. There can be a lot of variation in the glands of any one plant, and it’s important to look at several leaves to confirm which variety you have. Non-native plants are common along roadsides, trails, and hedgerows across the Island. I find the native plants more commonly in the wet woodlands of western PEI.
The bark of Highbush Cranberry has long been used to relieve muscle spasms and menstrual cramps and is sold commercially as ‘Crampbark’. Researchers have isolated a chemical dubbed viburnine with anti-spasmodic properties along with pain-relieving salicylic acid in the bark, supporting this traditional use. Work is ongoing into a wide range of other potential medicinal uses for this plant.
Highbush Cranberries are ripe now and will hang on well into the winter. Their fall foliage and bright red berries against the winter snow are beautiful parts of PEI untamed!
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