Iowa wildflower Wednesday: Black raspberry

I’m not much of a forager, but every summer I try to pick some berries. Black raspberry (Rubus occidentalis) typically flowers in Iowa in May, sometimes in early June if we had a late spring.

You can find these plants in the wild in almost every Iowa county, especially in woodland openings or near woodland edges. Keep an eye out for the shrubs while walking or bicycling on trails or roadsides. Then circle back in late June or early July to harvest what wildlife have left behind.

Illinois Wildflowers offers this tip for gardeners who want to cultivate black raspberry: “The preference is partial sun, moist to mesic conditions, and rich loamy soil. In areas that are too sunny and dry, the fruit may not develop properly without adequate rain. The canes also fail to set fruit if there is too much shade.” Although we have partial sun, we didn’t have luck growing these shrubs in our yard, probably because deer and rabbits like to eat the canes and foliage.

About ten years ago, the city of Clive did some sewer work near North Walnut Creek that destroyed my favorite area to pick black raspberries in Windsor Heights. I took all of the photos enclosed below in May or June 2023 near Colby Woods Drive, a little north of Hickman Road and not far from North Walnut Creek in Urbandale.

You may find larger colonies than this one.

How do you know if you are looking at black raspberry plants or blackberry plants (Rubus allegheniensis)? Timing is the first clue: black raspberry blooms earlier, and the fruit usually ripens by early July. If you see fruit ripening later in July, it’s probably blackberry. (Unlike some cultivated red raspberry varieties, which may produce fruit until the first frost, native black raspberry or blackberry plants produce one crop of berries per year.)

In this post from the Identify that Plant website, “Angelyn” provides other helpful tips and side by side comparisons. Black raspberry leaves are lighter on the underside.

The canes also help distinguish the species. While both plants have thorns, “The Black raspberry stems are notably glaucous (bluish white). […] The Blackberry stems have ridges and angles while the Black raspberry stems are smoothly round-shaped (nearly circular in diameter).”

In a colony, you may see new canes growing from older parts of the plant, which have a woody appearance after the winter.

The buds develop in clusters. They won’t all bloom at the same time.

One flower is open while nearby buds are closed.

Minnesota Wildflowers describes black raspberry flowers as follows:

Flowers are white, 1/3 to ½ inch across with 5 oblong to narrowly spatula-shaped petals that are initially erect, becoming ascending to widely spreading. In the center is a cluster of many styles surrounded by a ring of numerous white stamens. Alternating with the petals are 5 sepals, broadly triangular tapered to a long, tail-like tip, longer than the petals, widely spreading to curved downward (recurved), pale green to gray-green, the outer surface covered in soft, non-glandular hairs.

Many kinds of insects, especially bees, visit the flowers or feed on parts of the plant. I’m not sure what insect is pictured here.

The berries (technically “compound drupes”) are green at first.

As the fruit ripens, it turns red, but you don’t want to pick the berries until they are very dark, almost black.

You may want to visit the colony several times, because the berries won’t ripen at the same rate.

Long sleeves and long pants, preferably jeans, are essential when picking black raspberries. I guarantee you will get stuck by some of the thorns on the canes. Put on some mosquito repellent as well; with the rain we’ve had this year, you will need it.

Returning to Angelyn’s tips on distinguishing black raspberry and blackberry plants, you can spot “one more notable difference” when you pick a berry.

The Blackberry fruit pulls away from the plant — leaving a rather flat receptacle on the plant. The Black raspberry fruit pulls away and leaves a sizable cone-shaped receptacle. […]

Correspondingly, the Blackberry fruit is nearly flat across the part of the berry which was attached to the plant, while the Black raspberry fruit has a deep indentation in the berry.

You can see the cone-shaped part where I just picked a berry.

And here’s the indentation in the berry.

Tags: Wildflowers

About the Author(s)

Laura Belin

  • One tribute to the flavor of wild black raspberries...

    …is that their Iowa devotees are very willing to deal with the skeeters and thorns. Long ago, an Iowa friend served me wild black raspberries on homemade vanilla ice cream, heaven in a bowl. Thank you for bringing back that memory.

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    I usually pick a few gallons every year. We have several good ‘patches’ on our farms and black raspberry pie is a family favorite. We have planted and maintain Jewel black raspberries as well as picking the wild ones. This spring we planted ‘Ohio Treasure’ which are a black raspberry that produces in later in the summer until frost, similar to red raspberries.
    Black Raspberries respond well to high organic matter so adding compost helps tremendous with yield. Also, the old canes need to be removed each year after they are done bearing in order to reduce disease pressure.
    And yes, pie crust is always made with lard!

  • Black raspberries

    I agree with Prairie Fan about the mosquitos and thorns. We have a patch of black raspberries that grow on our property. We did not plant them. On the advice of my neighbor, I prune them early every spring. They seem to produce more and bigger berries as a result. My wife bakes a raspberry crunch with an oatmeal/brown sugar/flour crust mixed in with the raspberries. And you can have ice cream on top of that.

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    One more bug to worry about,TICKS!