Wild Cucumber, Echinocystis lobata

Flowering wild cucumber covering a dead spruce tree.

Flowering wild cucumber covering a dead spruce tree.

In late summer you may notice trees or shrubs festooned with crowns of white flowers that obviously are not the woody plant blooming. Look closely and you’ll notice the leaves and individual flowers look just like that of cucumber – this is wild cucumber or balsam-apple, Echinocystis lobata. The name Echinocystis comes from the Greek echinos for “hedgehog” and cystis for “bladder”, appropriately describing the spiny fruit.

A vining native annual in the cucumber or gourd family (Cucurbitaceae), wild cucumber is often overlooked until it is large and sometimes has engulfed the other plants it is growing on. It occurs throughout much of North America, including all of Wisconsin. Its native habitat is along streambeds, swamps, and moist thickets or roadsides.

A seedling wild cucumber.

A seedling wild cucumber.

It is not common in home landscapes, but will occasionally be spread from adjacent rural areas.

As a fast-growing, warm season annual, wild cucumber grows from seed each year, germinating after the last frost. The large, oval cotyledons look just like that of a regular cucumber. The smooth, fleshy stems are grooved lengthwise. The large, alternate leaves are palmate with 3-5 pointed lobes. Each is borne on a long petiole. The branching vines can grow up to 25 or 30 feet long, climbing onto other foliage with curling, 3-forked tendrils that arise from the leaf axils. The tendrils coil when they touch anything to attach onto for support.

The palmate leaves are deeply lobed (L). Curling tendrils arise from leaf axils (R).

The palmate leaves are deeply lobed (L). Curling tendrils arise from leaf axils (R).

Wild cucumber in full flower.

Wild cucumber in full flower.

Starting in mid-summer the vines begin to produce fragrant, pale yellowish-white flowers. The plants are monoecious (separate male and female flowers are produced on the same plant) and the flowers are pollinated by insects. The numerous male flowers form in clusters on a long, erect raceme from the leaf axils. Each ½ – ¾ inch wide flower has 6 long, thin petals, giving a star-like appearance. The filaments of the three stamens form a column, with the yellow anthers on the end. The female flowers occur singly or in pairs interspersed among the male flowers, with a small, rounded spiny ovary below the yellow-green petals.

The male flowers are produced in large racemes (L), with each flower having 6 long, thin petals (R).

The male flowers are produced in large racemes (L), with each flower having 6 long, thin petals (R).

Superficially the fruit resembles a small and rounded cultivated cucumber, but with prickles all over it. The puffy, spherical to oblong, green pods with long, soft spines grow up to two inches long. Despite the common name, the fruits are not edible, and can cause burning reactions in some people. The pods can be used in dried flower arrangements.

Female flowers have a prickly ovary beneath the petals, which quickly devlops into the spiny fruit.

Female flowers have a prickly ovary beneath the petals, which quickly develops into the spiny fruit.

When ripe, the fruit becomes dry and brown and the inflated capsules burst open at the bottom to eject the seeds. Each pod contains four large, flat black or brown seeds, two in each of the two cavities in the pod. The fruits should be bagged well before maturity if you wish to collect seed, as they are forcibly expelled by hydrostatic pressure as soon as the pods are dry.

The mature fruits (L) dry out (C) and expell the dark brown or black seeds (R).

The mature fruits (L) dry out (C) and expel the dark brown or black seeds (R).

Wild cucumber can look like strings of green Chinese lanterns hanging in a tree.

Wild cucumber can look like strings of green Chinese lanterns hanging in a tree.

Wild cucumber can be cultivated as an ornamental annual vine, and would be great for covering arbors and pergolas, or for rambling horizontally along fences, walls and other low structures. It does best in full sun and rich, moist soil. Seed can be sown directly outdoors as soon as the soil warms, or seeds can be started early indoors to be transplanted outside after the last frost. Only a few suppliers offer seed (one is Prairie Moon Nursery in Minnesota at www.prairiemoon.com/), so you may have to collect your own seed in the fall to grow the following year.

Wild cucumber is an aggressive vine that can nearly smother small trees.

Wild cucumber is an aggressive vine that can nearly smother small trees.

Even though this is an attractive native plant, it is generally considered a weed when climbing on planted trees because of its aggressive growth. It is easily controlled in the home landscape by pulling or hoeing the young plants. Plants will self-seed readily, so controlling before the plants begin to flower and fruit is important for reducing infestations. Chemical control can be used over larger areas, such as shelter belts.

Another similar, but less common, plant is bur cucumber, Sicyos angulatus, but that plant is easily differentiated by the degree of indentation of the leaf lobes and the fruits. Wild cucumber has deeply lobed leaves and inflated fruits, while bur cucumber has broad, shallowly lobed leaves and the fruit is much smaller and not inflated.

– Susan Mahr, University of Wisconsin – Madison


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20 comments

  1. I found this growing in a pot I had from last year! I thought it was a squash or cucumber that reserved itself. I have not ever seen this before and so glad I figured out what it was! I’m in Western Massachusetts!

  2. “Invasive species” are living things that are not native to an area that come in and take over. Think Asian carp, garlic mustard, giant hogweed, sea lamprey, zebra mussels, purple loosestrife, Eurasian millefoil.

    This is why wild cucumber does not meet the definition of “invasive.” It is native to Wisconsin (I remember it growing up). It is simply a fast-growing plant that vines on tall things in its area. It does not hurt most things it climbs on, though as pointed out in the article, it can smother out small trees and bushes. Some years are better than others, of course.

  3. I think it’s become invasive. I’ve lived in Wisconsin most of my life and I’ve never seen this, before. It’s covering all of the roadside trees and vegetation. It definitely seems out of control.

    • I used to see this all the time growing up in west-central Wisconsin. It came on in the fall in a small wooded/brushy area near my home that the neighborhood kids used as a “hideout.”

  4. I’m not going to lie, this wild cucumber plant is vining around our poles we have around the fire pit and it looks absolutely beautiful!

  5. Am so glad I am on this sight, I now know to no longer eat these cumumbers anymore. Never ate many but when weeding tried some. So glad I didn’t get sick, or ate too many!! They sure have grown fast this yr in N FL

  6. We need to go talk to some of our southern State friends to see what damage this plant does. We have seen it in many southern states engulfing entire wood-lines like rolling hills of vines. It is not good! Talking to a farmer in Louisiana last summer where it is totally covered farmlands – he told us that it smothers everything beneath it with a thick vine & leaves that block out the sun below. It got into a back field of hay and before he found it, the field was dead but then covered with this vine. It climbed into his neighbor’s trees (in the woods) then came across the top of this farmer’s woods – totally covering it. It took about 3 yrs and the trees all started to die – acres of trees. He said it made a canopy above the trees and blocked out all sunlight in the woods – a real mess. For me – I try to destroy it where ever we find it on the farm. I suspect we will pay later for not dealing with this vine today.

  7. I live in northeast Iowa and this is everywhere along almost every roadside. Never have I seen it until this year. I do like how pretty it looks but I do wonder about the plants it’s engulfing.

  8. Sometimes a native plant can become invasive if the animal that used to eat it went extinct, like, say, a mastodon or ground sloth?

  9. I drove 1/2 hour drive the other day north of Plain Wi. These things covered nearly everything along both sides of HWY 23. If they are not invasive I don’t know what is. It is as bad as the Kudzu vine plant in the south…or worse.

  10. There seems to be a huge amount of this Wild Cucumber growing along the roadsides this year. Especially along I-90/94 and Route 53 all across the State. Is there more this year and if so why?

  11. From Dodge County UW-Extension, 08/20/13:
    “If wild cucumber is a weed in your landscape, it is easy to control. Although not considered invasive, because it is native to Wisconsin, it certainly is aggressive and will take over trees, bushes, and small creatures in a single bound. Well, maybe not small creatures. It just seems that way sometimes.

    If possible, pull or hoe the plants early in the spring as soon as they are found. The seedlings look exactly like garden cucumbers. If they are more established, repeated mowing before they set seeds will keep them in check. If they have progressed to the point that they are growing up into trees and bushes, simply pull them out and discard them. Ideally, get them out BEFORE they go to seed. This will reduce the number of plants in the area over time.
    Chemical controls may be used when necessary. Dicamba, the active ingredient in some post-emergent herbicides, is one option. However, do not use it under the canopy of trees and shrubs as it can be taken up through plant roots. Rain or irrigation water can wash it into the root zone where it will be a problem.
    Another option is glyphosate, the active ingredient in post-emergent herbicides such as Round-Up. It can be applied to young plants early in the season. This product may be used around trees as it will not be absorbed by the roots or bark. However, it also kills almost anything green and growing that it touches, so take care to keep it off desired plants. Always read and follow directions when using any chemical control. ”
    https://dodge.uwex.edu/2013/08/wild-cucumber-invasion/

  12. This plant is nothing but outrageously invasive and destructive to our woodlands. It is easy enough to pull out but to use it as an ornamental plant is crazy. It is has been choking out the new growth destroyed by Mother Nature by wrapping itself completely around it and not allowing in any light.

    • Exactly!! Why in the world is this not considered an invasive, native or not? Simply because it is native? One needs only look around or at the photo above aptly captioned “Wild cucumber is an aggressive vine that can nearly smother small trees.” in order to posit the idea of its detrimental nature. Easily pulled up? Good luck.

    • It’s not invasive because it is native. The definition of invasive is non-native species that spreads so much it causes damage to an ecosystem. It’s obviously a problem just not invasive by definition.

  13. It is a noxious plant that is taking over areas by lakes, streams, marshes and now seen in so many places, crawling up and choking Beautiful trees, shrubs etc. I would not plant it, it is too vigorous and gets out of hand quickly.

  14. It’s a beautiful plant with interesting seeds, as long as it is not choking a spruce tree.

  15. I have seen this growing in ditches but not trees. I like the idea of pods for Halloween decorations!

  16. wild cucumber is easily controlled in the home landscape by pulling before flowering, I have used the pods for Halloween decorations

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