The Outside Story: Blackberry season begins

By Rachel Sargent

The bank in front of our house is a dense tangle of arching canes and thorns as large as cat claws. I wriggle further in, lips pressed against the pain of scratches and fingers straining for that last, fattest, blackest berry. I brush it, and it falls into the gloom of leaves and grass, never to be retrieved. Disentangling myself, I take my bowl of berry plunder back to the house where my dad will make the best pie I know: wild blackberry.

Wild blackberries are delicious, grow like weeds, and ripen in August, just in time for my birthday. They belong to the rose family along with raspberries, strawberries, the stone fruits, and unexpectedly, almonds.

It is unlikely to surprise anyone that blackberries are closely related to raspberries. People often mistake black raspberries for blackberries, but there are easy, tell-tale differences between these plants. Here’s the quick and dirty way of distinguishing between them: both black and red raspberries pull off their stem completely, leaving a hollow or dome-shaped fruit, but blackberries have a fleshy core, making them more solid.

When the plants aren’t fruiting, they are much more difficult to tell apart. Both grow as a tangle of canes with compound leaves of three to five leaflets. However, again, a closer look reveals differences. The thorns of blackberries are straight while black raspberry thorns are hooked. Both berries have white flowers with five petals, but the petals of blackberry flowers spread out to look like a five-pointed star, while black raspberry flowers have stubbier, close-set petals giving the whole flower a rounder shape.

In one of those ironic twists of botany, despite their name, blackberries are not considered berries at all. They are aggregate fruits made up of juicy little spheres called drupelets. Aggregate fruits come from a single flower, but each carpel (the female part of a flower) forms a fleshy fruit with a stony covering over the seed. The seeds in the drupelets of blackberries are so small that they are hard to see, but you can imagine all those little seed pips as itty-bitty peach pits. A true berry (as a botanist would define one) is a fleshy fruit produced from one ovary in the flower. This means strawberries aren’t berries either, but blueberries really are berries. And to further confuse you, so are tomatoes and bananas. (Botanists like to make fruit terminology difficult for the rest of us).

The rich, dark color that gives blackberries their name comes from a group of organic compounds called anthocyanins. Anthocyanins are common plant pigments, ranging from red to purple to blue,  depending on the pH the pigment is exposed to in the plant’s tissues. Red autumn leaves, purple pansies, and blueberries all owe their color to anthocyanins. In flowers, the anthocyanin color is used to say “Here I am! Pollinate me!” In fruits, its message is, “Eat my seeds!” Not only do blackberries use anthocyanins to advertise when they are ripe, they have something called “pre-ripening fruit flags.” That means they go through several color changes, from green to white to red, before finally ripening to black. These pre-ripening colors are signals (or flags) to animals that the berries will be ready soon.

Anthocyanins do more than just make pretty colors. They can act as a kind of plant sunscreen, blocking blue-green and ultraviolet wavelengths that can damage sensitive tissues. This is why new leaves have red anthocyanins in them, even though, unlike fruits, they do not want to be eaten. And as a final perk, anthocyanins are powerful antioxidants, so don’t feel so guilty about sneaking that extra piece of blackberry pie.

People aren’t the only ones who love to eat blackberries. Many times out picking, I’ve had a show-down with a beetle, ant, or slug over just which of us will get a berry. Of course, larger animals – birds, bears, rodents and other wildlife – eat blackberries too, and play an important role in dispersing seeds through defecation. By hitch-hiking inside an animal, blackberry seeds can travel long distances.

This is the reason plants often seem to spring up overnight, as soon as there’s an open spot in the woods for them.  I’ve seen this effect close to home, although not with wildlife. My dog loves blackberries and will eat them right off the canes. Thanks to her, we now have blackberries in far-flung patches around the house.

Rachel Sargent is an educator with the Fairbanks Museum, as well as a freelance nature writer and illustrator. The illustration for this column was drawn by Adelaide Tyrol. The Outside Story is assigned and edited by Northern Woodlands magazine and sponsored by the Wellborn Ecology Fund of New Hampshire Charitable Foundation: wellborn@nhcf.org