Melilotus albus (White Sweet Clover)
| Also known as: | Honey Clover |
|---|---|
| Genus: | Melilotus |
| Family: | Fabaceae (Pea) |
| Life cycle: | annual, biennial |
| Origin: | Eurasia |
| Status: |
|
| Habitat: | sun; disturbed soil; fields, prairies, roadsides, railroads, gravel pits, empty lots, shores, river banks, woodland edges |
| Bloom season: | June - October |
| Plant height: | 2 to 9 feet |
| Wetland Indicator Status: | none |
| MN county distribution (click map to enlarge): |  |
| National distribution (click map to enlarge): |  |
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Detailed Information
Flower: 
![[photo of flowers]](/udata/r9ndp23q/white/melilotus-albus-white-sweet-clover_0622_135913.jpg)
Flowers are clustered in spike-like racemes up to 8 inches long on branching stems, arising from leaf axils, and at the top of the plant, each with 20 to 120 flowers. Flowers are white, up to ~¼ inch (3.5 to 6 mm) long, pea-shaped, the upper petal (banner) flaring up, the lateral petals (wings) distinctly smaller. The calyx cupping the flower is light green with 5 narrowly triangular lobes about as long as the calyx tube. Flower stalks are shorter than to about as long as the calyx tube.
Leaves and stems:
![[photo of leaves]](/udata/r9ndp23q/white/melilotus-albus-white-sweet-clover_0531_135709.jpg)
Leaves are alternate, compound in groups of 3 on a stalk about 1 inch long. Leaflets are 3/8 to ~1½ inches (1 to 4 cm) long, up to ~½ inch (to 15 mm) wide, variably shaped from nearly diamond-shaped to oval-elliptic to lance-oblong, rounded to flattened at the tip, wedge-shaped at the base, green to blue-green or gray-green. Edges are toothed, surfaces mostly hairless.
![[photo of stipule and stem]](/udata/r9ndp23q/white/melilotus-albus-white-sweet-clover_0531_135747.jpg)
At the base of the compound leaf stalk are a pair of appendages (stipules) up to 3/8 inch (1 cm) long, awl-shaped to bristle-like, those on the lower stem sometimes lobed or toothed. Stems are usually much branched, may be ridged or grooved, are mostly hairless and green or sometimes tinged red. Plants can grow tall and spindly or shorter and bushy.
Fruit:
![[photo of developing fruit]](/udata/r9ndp23q/white/melilotus-albus-white-sweet-clover_0714_103026.jpg)
Fruit is an oval pod 3 to 6 mm long with a bit of the style persisting at the tip. The surface is covered in a network of connected ridges/veins, the space between them typically about as long as wide.
![[photo of seed]](/udata/r9ndp23q/pd/melilotus-alba-seed-1.jpg)
Each pod contains 1 or 2 seeds about 2 millimeters long that ripen to brown.
Notes:
Like the closely related Yellow Sweet Clover (Melilotus officinalis), White Sweet Clover was brought to North America as a forage crop and quickly escaped cultivation. It is commonly found in the disturbed soils of roadsides, old fields, trail edges and empty lots, but also encroaches in high grade habitat and can have explosive growth following fire disturbance.
The most obvious difference between the two Sweet Clovers is flower color, with Yellow starting to bloom a couple weeks earlier than White, but when flowers are not present these two are very difficult to distinguish, relying on the texture of mature pods (Yellow=elongated ridges/veins vs. White=shorter ridges/veins). But I have to wonder if it really matters which one you have? Both are ubiquitous in Minnesota and equally problematic in natural areas.
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More photos
White Sweet Clover plant
White Sweet Clover plants
a wall of White Sweet Clover established in a Wildlife Management Area
leaflets are somewhat variable in size and shape
White Sweet Clover plant
White Sweet Clover plants
a wall of White Sweet Clover established in a Wildlife Management Area
leaflets are somewhat variable in size and shapePhotos by K. Chayka taken at various locations across Minnesota. Photos by Peter M. Dziuk taken in Ramsey County.
Comments
Have you seen this plant in Minnesota, or have any other comments about it?
on: 2014-07-08 21:55:43
I have one tall volunteer in my garden near my pond. It is beautiful--but should I pull it?
on: 2014-07-09 07:07:45
Carey, it may be but one plant now, but can turn into a whole yard full, then run into your neighbor's yard, the roadside (which will allow it to spread even further from car and bike tires, dog walkers, and pedestrian footwear) and by critters, wind and rain. People think one little plant in their yard can't hurt but that is not true. I'd yank it before it has a chance to set any seed. Plant a native in its place!
on: 2014-07-20 20:39:07
We are being overrun by this invasive at River Bend Nature Center this year! I'm noticing an especially large amount of them in places that we burned last year. Could they have taken advantage of the burn to spread their seed? They have reached hedgerow proportions in many spots! I don't remember it being quite that bad in years past.
on: 2014-07-21 04:14:19
Unfortunately, sweet clover is known to respond to fire in exactly the way you describe, Jill.
on: 2014-07-21 17:37:39
It is very fragrant, right? The wetland where I work was burned last year, and is now covered in this stuff. It really spread this last week or so.
on: 2015-08-25 23:29:17
Once you pull the weeds, how do you dispose of them? I'm guessing you wouldn't want to put them in your compost pile, and if burning encourages growth what can you do to kill the seed? Is there a good general disposal (after removal) method for most invasives?
on: 2015-08-26 06:46:45
Sarah, unfortunately there are no good options to the average landowner for disposal of weeds. See MDA's Guide to Removal and Disposal of Weeds.
on: 2017-08-27 11:18:40
This invasive weed is easier to pull in its first year of growth when it's not grown more than a foot high. Better to pull it as soon as you see it. Seeds seem to be brought in during construction.
on: 2018-07-20 14:43:34
Picked Sweet White Clover or Melilotus alba can be burned prior to seeding without spreading more. The reason fire caused it to grow more at River Bend Nature Center was the fire took away competitors for resources. Its roots grow very deep, and fire won't harm it like a prairie grass. Why would you want to destroy it though? It may not be native, but it helps hold the ground together preventing erosion, its a nitrogen fixer - making the soil richer than before it grew, and it's a wonderful nectar source for the honey bee and many butterflies. The honey bee is in peril right now, and your all advocating destroying one of their best food sources.
on: 2018-07-20 15:16:02
Kevin, honey bees are not globally threatened. Besides they are of European origin and compete with native bees, which actually are threatened. I'd worry about the natives more. They need greater diversity, not more sweet-clover.
on: 2019-07-07 21:01:44
If you cut these down to the ground, would they still come back? Or if you cut them down "twice" (1st year and 2nd year) would they then truly die as a biennial? I have contaminated soils and can't remove soil.
on: 2019-07-23 17:46:33
It appears that seeds of sweet white clover were in the mix that our septic company used when installing our septic system and needed to plant on the mound. This plant is not wide spread on our property, just here (for now). After learning that it was invasive, I started pulling it but then noticed the many different types of bees and insects coming to it. I'd much rather have native plants there in it's place but should I leave it for the bees? Most of it has already flowered and a lot of it is 4-5 feet tall. I don't mind putting in some sweat work pulling if it will help in the long run - not going to burn the septic mound so I'm not sure what other options I'd have! Seems like the advice is to get rid of it, but just checking for the bees and other insects!
on: 2019-07-23 19:38:52
Jennifer, I would replace it with native plants. Sweetclover spreads too easily. Hand pulling should do the trick.
on: 2021-05-28 16:04:01
Planted sweet prairie clover by mistake in one of my native garden beds (was mislabeled by provider. It flowered first year and began to take over 2nd year. I pulled much of it before flowering and the rest cut before flowering. This year I've pulled all of it BUT unable to get most by the roots. As I see it, I cut it or pull it as close to ground as possible. Will it eventually die away if I do this every year? Also, will targeted RoundUp on it help? I don't use any chemicals but would be open to just spraying the new growth of this invasive clover if it means getting rid of it forever.
on: 2021-05-28 19:54:17
Lorie, sweet clover is an annual or biennial so Round-up would not do much to reduce its spread. You do have to contend with the existing seed bank until it's depleted. Pull up new plants to prevent it producing more seed.
on: 2023-08-11 16:00:37
This has exploded for us this year-also Birdsfoot trefoil. May have been in septic mix SWCD sold a year or so ago? But some plants seem several years old. Expanded to cover nearly all sunny areas. At least taproot fairly easy to pull. Bumblebees and our honeybees do like it, but plenty of other pollinator choices.
on: 2023-08-16 17:03:24
Just realized this is growing on the side of my house in a small rhubarb bed and it is COVERED in bees. I have lots more polinater plants in my yard and they are also being utilized by the bees. I may regret it but I'm leaving it til frost and will then start the battle. Many of my neighbors are using chemicals on their lawns so there is that.