Yellow Sweet Clover

Melilotus officinalis

mel-il-LOW-tus  oh-fiss-ih-NAH-liss

Synonyms of Melilotus officinalis (51) (Updated on 12-18-23 from Plants of the World Online): Brachylobus officinalis (L.) Dulac (1867), Medicago officinalis (L.) E.H.L.Krause (1901), Melilotus armenus Boiss. (1849), Melilotus arvensis Wallr. (1822), Melilotus arvensis var. albus St.-Lag. (1889), Melilotus arvensis var. grandiflorus Lamotte (1876), Melilotus arvensis proles luxurians Rouy (1899), Melilotus arvensis proles maximus (Legrand) Rouy (1899), Melilotus arvensis var. maximus (Legrand) St.-Lag. (1889), Melilotus bungeanus Boiss. (1872), Melilotus citrinus Duval ex Steud. (1821)(not validly publ.), Melilotus diffusus W.D.J.Koch ex DC. (1815), Melilotus expansus Rchb. (1832), Melilotus flavus Pall. (1776), Melilotus kochianus DC. (1815)(nom. illeg.), Melilotus longipedicellatus Rosbach (1875), Melilotus lutescens Gilib. (1782)(opus utique oppr.), Melilotus luteus Gueldenst. (1791), Melilotus luxurians Shuttlew. ex Rouy & Foucaud (1899), Melilotus macrorhizus Besser (1821)(nom. illeg.), Melilotus macrorrhizus var. palustris (Waldst. & Kit.) W.D.J.Koch (1839), Melilotus macrospermus K.Koch ex Boiss. (1872), Melilotus mauritanicus Willd. (1809), Melilotus maximus Legrand (1873), Melilotus melilotus-officinalis (Crantz) Asch. & Graebn. (1898)(orth. var.), Melilotus montanus Gaudin (1829), Melilotus nebrodensis Jord. ex Nyman (1878)(not validly publ.), Melilotus neglectus Ten. (1836), Melilotus officinalis var. expansa Mutel (1834), Melilotus officinalis var. maximus (Legrand) Kojić (1972), Melilotus officinalis f. maximus Legrand (1899), Melilotus officinalis var. vulgaris Wahlenb. (1826), Melilotus pallidus Besser (1823), Melilotus paluster Menyh. (1877)(orth. var.), Melilotus palustris (Waldst. & Kit.) Schult. (1814), Melilotus petitpierreanus Willd. (1809), Melilotus petitpierrianus Willd. ex Ces., Pass. & Gibelli (1886)(orth. var.), Melilotus rugosus Gilib. (1782)(opus utique oppr.), Melilotus virescens Jord. (1853), Sertula arvensis (Wallr.) Kuntze (1891), Sertula bungeana (Boiss.) Kuntze (1891), Sertula maior Lunell (1916)(nom. superfl.), Sertula officinalis (L.) Kuntze (1891), Sertula pallida (Besser) Kuntze (1891), Trifolium mauritianum Steud. (1821)(not validly publ.), Trifolium melilotus-mauritanicum Schousb. (1800), Trifolium melilotus-officinarum Crantz (1766)(orth. var.), Trifolium officinale L. (1753), Trifolium palustre Waldst. & Kit. (1812), Trifolium petitpierreanum Hayne (1807), Trifolium vulgare Hayne (1807), Trigonella officinalis (L.) Coulot & Rabaute (2013)

Melilotus officinalis (L.) Lam. is the accepted scientific name for the Yellow Sweet Clover. It was described as such by Jean-Baptiste Pierre Antoine de Monet de Lamarck in Flore Françoise in 1779. It was first named Trifolium officinale by Carl von Linnaeus in the second volume of the first edition of Species Plantarum in 1753. 

Melilotus officinalis was first named by Peter (Pyotr) Simon von Pallas in 1776, but for some reason, his description was invalid (“nom. inval.”) (Melilotus officinalis Pall., Reise Russ. Reich. 3: 537 (1776), nom. inval.).

The genus, Melilotus (L.) Mill., was named and described as such by Philip Miller in The Gardeners Dictionary in 1754. It was first listed as Trifolium sect. Melilotus by Carl von Linnaeus in the second edition of the first volume of Species Plantarum in 1753.

As of 12-18-23 when this page was last updated, Plants of the World Online lists 23 species in the Melilotus genus. It is a member of the plant family Fabaceae with 793 genera. Those numbers could change as updates are made on POWO.

The above distribution map for Melilotus officinalis is from Plants of the World Online. Obviously, the species has a much broader range in North America, but I wanted to share this map to show where the species is native. Areas in green are where the species is native and purple is where it has been introduced.

POWO gets their maps for the United States and Canada from Flora of North America for families recognized on that site. When I wrote this page FNA had not yet included genera from the plant family Fabaceae. FNA will be coming out with the Fabaceae family very soon then POWO will update their maps accordingly. We are all a work in progress.

The above map is from the USDA Plants Database. As shown in blue, the species has been introduced throughout the United States and most of Canada.

The map on iNaturalist shows where members have made observations. Anyone can join and it is a great website to confirm and share your observations. The maps on iNaturalist are continually updated as new observations are made.

THERE ARE SEVERAL LINKS AT THE BOTTOM OF THE PAGE FOR FURTHER READING AND TO HELP WITH A BETTER POSITIVE ID.

I found this small colony of Melilotus officinalis (Yellow Sweet Clover) while working on a friend’s farm in 2019. Although the species is found throughout Missouri, and all over the country, it was the first time I had ever seen any. I hoped to get back out to the farm in 2020 for more photos but I became fairly busy and didn’t go.

In 2022, I found plants in the back pasture on May 5… I did put them on iNaturalist the same day and a member agreed they were photos of Melilotus officinalis and the observation became Research Grade. The problem is, all 8 photos are of leaves. The photos of the flowers must have been blurry perhaps from the wind blowing. I forgot all about the photos until I was updating this page on December 23 and I saw them in the species photo folder. DUH!!! Most of the 2022 photos are at the bottom of the page under the links for further reading… I got to wondering why I kept so many leaf photos… I suppose because I wanted to get all the information I could then I forgot about them. I really need close-ups of the flowers but that can be difficult with some species. The light has to be perfect with no wind blowing…

Melilotus officinalis is another sweet clover that was introduced to North America and other countries from Eurasia. It was brought here for the same reason as Melilotus albus, a forage crop. It is an annual or biennial species that has escaped cultivation to become invasive in many areas throughout the world. It can displace native species, especially those that grow shorter.

The species, like many clovers, will grow in just about any type of soil and climate. It has a deep tap root which allows it to be drought tolerant. This species can grow from 2-7’ tall depending on soil type and climate.

The plants generally grow erect, but they may sprawl somewhat. Stems are round, sometimes with ridges, and can be smooth (glabrous) or may have a few short hairs (pubescent).

The trifoliate leaves grow in an alternate pattern along the stems. The leaves have three leaflets that are variable in shape from oblanceolate, obovate, oblong, oblong-ovate, or oblong-elliptic. The leaves have toothed margins and can be hairless (glabrous) or slightly hairy (pubescent).

The compound leaves have a petiole (leaf stem) about an inch long with a pair of stipules at the base. The lateral leaflets have small petiolules while the center leaflet is larger and has a longer petiolule (stem of a leaflet).

Flowering stems emerge from the axis of upper leaves which terminate in racemes of numerous yellow flowers.

The flowers have 5 yellow petals (corollas) and are surrounded by a green calyx with 5 teeth. The petals, like other members of the plant family Fabaceae, consist of a standard, a keel, and two wings. With this species, the standard is the larger upper petal that curves upward and is notched in the center. The keel is the boat-shaped petal on the opposite side of the standard, and the wings are the lateral petals on either side. The flowers have 10 stamens with 9 fused filaments and one filament that is basically free to the base. I need a very close-up photo of that…

Melilotus officinalis makes a great honey plant and is attractive to long and short-tongued bees, flies, and wasps. Butterflies, skippers, and beetles also occasionally visit the flowers. Caterpillars of some butterflies eat the leaves. In native habitats where the Yellow and White Sweet Cloves have become invasive, bees and other pollinators feed on the clover rather than helping to pollinate other wildflower species.

Improperly cured hay that becomes moldy can be toxic to cattle due to the coumarin content in sweet clovers. The coumarin converts to an anticoagulant (dicoumarol) which can lead to internal hemorrhaging and death. Although the plants are somewhat bitter tasting, cattle can sometimes overeat even live plants which can cause similar issues.

Melilotus officinalis (Yellow Sweet Clover) is similar to Melilotus albus (White Sweet Clover) and have been considered the same species by some botanists. They often grow in the same location.

I have enjoyed photographing and learning about the many wildflowers growing on the family farm and in other areas. The farm is in Windsor, Missouri in Pettis County (Henry County is across the street, and Benton and Johnson aren’t far away). I have grown over 500 different plants and identified over 250 species of wildflowers (most have pages listed on the right side of the page). I am not an expert, botanist, or horticulturalist. I just like growing, photographing, and writing about my experience. I rely on several websites for ID and a few horticulturalists I contact if I cannot figure them out. Wildflowers can be somewhat variable from location to location, so sometimes it gets a bit confusing. If you see I have made an error, please let me know so I can correct what I have written.

I hope you found this page useful and be sure to check the links below for more information. They were written by experts and provide much more information. Some sites may not be up-to-date but they are always a work in progress. If you can, I would appreciate it if you would click on the “Like” below and leave a comment. It helps us bloggers stay motivated. You can also send an email to me at thebelmontrooster@yahoo.com. I would enjoy hearing from you especially if you notice something is a bit whacky.

FOR FURTHER READING:
PLANTS OF THE WORLD ONLINE (GENUS/SPECIES)
INTERNATIONAL PLANT NAMES INDEX (GENUS/SPECIES)
TROPICOS (GENUS/SPECIES)
FLORA OF MISSOURI (GENUS)
WORLD FLORA ONLINE (GENUS/SPECIES)
WIKIPEDIA (GENUS/SPECIES)
USDA PLANTS DATABASE
DAVE’S GARDEN
MISSOURI PLANTS
iNATURALIST
WILDFLOWER SEARCH
ILLINOIS WILDFLOWERS
MINNESOTA WILDFLOWERS
KANSAS WILDFLOWERS AND GRASSES
CABI (INVASIVE SPECIES COMPENDIUM)
PFAF(PLANTS FOR A FUTURE)
GO BOTANY
U.S. WILDFLOWERS
FLORA FINDER
FRIENDS OF THE WILDFLOWER GARDEN
WILDFLOWERS OF NEW MEXICO
SOUTHWEST DESERT FLORA
INVASIVE PLANT ATLAS
UNIVERSITY OF WASHINGTON
MARYLAND BIODIVERSITY PROJECT

NOTE: The data (figures, maps, accepted names, etc.) may not match on these websites. It depends on when and how they make updates and when their sources make updates. Some websites have hundreds and even many thousands of species to keep up with. Accepted scientific names change periodically and it can be hard to keep with as well. Some of the links may use a name that is a synonym on other sites. In my opinion, Plants of the World Online by Kew is one of the most reliable and up-to-date plant databases and they make updates regularly. I make updates “at least” once a year and when I write new pages or add new photos but I do get behind. We are all a work in progress. 🙂

Some sites may list the species name as Melilotus Officinalis (L.) Pall. which is invalid (“nom. inval.”).

MORE PHOTOS FROM 2022…