INVASIVE PLANTS - Technical Learning College

Hops Clover Trifolium dubium
Trifolium dubium (formerly T. minus) goes by several common names, including Least Hops
Clover, Small Hops Clover, Lesser Trefoil, Yellow Shamrock, & Kleiner Klee. The tiny flowers are
said to resemble h Hops Clover hops.
It is a very common mat-forming weed which erupts on roadsides & empty lots early in spring in
recently disturbed soil or wherever grass, including wild meadow grasses, was chopped short at
the end of the previous year. It is only two to six inches tall, so tries to get a head start on larger
plants, germinating its previous year's seeds in January or February.
It can be the dominant weed or miniature wildflower in April. Though it may still be blooming May
through July, other plants will have grown so much as to hide it, & the early-spring mats will be
overwhelmed by larger weeds & grasses. But it will still be seen until at least early July, popping
up in cleared gardening areas.
It is easily mistaken for another common wildflower, Black Medick (Medicago lupulina, but Black
Medic’s wee yellow flowers turn into a cluster of tiny kidney-shaped black seeds, & its trifoil
leaves have pointy tips. Black Medic’s range is world-wide, & Least Hops Clover is only slightly
less universal in its distribution. Both plants became distributed throughout the world at least a
century ago, when sailing ships routinely picked up alfalfa bales from Eurasia & Central Asia to
use as passing fill-in between more profitable shipments, then sold the bales to farmers in ports
of the New World & Pacific Islands. Sundry knapweeds also spread throughout the world from
this practice.
Like other clovers & legume family plants generally, Hops Clover helps bind nitrogen in poor soils.
Though some people fight it as an unwanted weed, it is in reality doing the soil a good deed.
Though adaptable to a wide range of conditions, it tends to die out of rich soils, & does not
compete well with big perennials. But for the most part, it cannot be gotten rid of, so it might as
well be appreciated for the real charm of so many teensy bright yellow flowers & miniature trifoil
leaves. While Hops Clover annoys people who want perfection in their lawns, others never even
notice it is all over the place. It is too small to make a particularly big display. It is one of the
smallest of clovers, though even at that, the tiny flowers are actually made up of about two-dozen
even more wee florets.
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