Sensitive Brier (Mimosa nuttallii)

Sensitive brier has a lot going for it. The flashy flowers are bright pink, the foliage responds to your touch and it provides forage for wildlife. That’s a lot to like about this little trailing plant.

Latin Name/Common Name- The genus name Mimosa is Greek in origin and means “mimic”.  Nuttallii honors Thomas Nuttall, the English botanist who studied plant life in the US in the 1800’s. The common name “Sensitive brier” was given because the leaves fold up when disturbed. It is also known as Devil’s shoestrings and Cat’s claw or Catclaw brier because of the prickles on the trailing stems. Mimosa nuttallii is a perennial in the legume (bean) family.

Bloom Color- There is nothing bashful about the flowers of Mimosa nuttallii. Each blossom is a globe composed of hot pink filaments with prominent yellow anthers at each tip.

Bright pink globes with yellow tips

         ??????????????????????           Macro image of the pink filaments and two-lobed yellow anther

Description- Mimosa nuttallii is a creeping plant with a length of 4 to 5 feet. The stem is variably green or pink and is covered with recurved prickles.

The alternate leaves are bipinnately (twice pinnate) compound. This means that each leaf is divided into primary leaflets which are further divided into secondary leaflets.

                            This is one bipinnately compound leaf of Mimosa nuttallii

                            Each of these is a primary leaflet arising from the leaf

                            This zoomed image is a secondary leaflet arising from a primary leaflet

                   Entire leaf                         Primary leaflet              Secondary leaflet

The leaves of Mimosa nuttallii respond to various stimuli by folding along the primary leaflet. You can initiate this reaction simply by touching a leaf. The folding also may occur due to wind or darkness- the leaves fold up at night. This reaction is termed seismonasty and is quite common in the Mimosaceae family. You can read more about seismonasty in plants here-

The flowers of Mimosa nuttallii arise on long stalks at the leaf axils.  Before blooming, the buds somewhat resemble green bramble fruits such as blackberry.

                                         Trailing stem with flower buds in late May

                               Zoomed image of a single bud showing prickles on stem

???????????????????????????????                                   Bud just beginning to open into many tiny flowers

??????????????????????                                                                          Peak bloom

OLYMPUS DIGITAL CAMERA                                       Blooms, buds and spent flowers along a stem

Bloom Time- Mimosa nuttallii may be found in bloom from mid-May to early September.

Habitat- Open fields and dry, rocky areas are preferred habitat for Sensitive briar. It is also seen growing at woodland margins.

                                     Mimosa nuttallii thriving on dry, rocky ground

What’s Growing Nearby? Grasses and sedges are found growing alongside Mimosa nuttallii. I’ve also seen another interesting plant- Spider Milkweed (Asclepias viridis) thriving nearby in the same open field.

OLYMPUS DIGITAL CAMERAOLYMPUS DIGITAL CAMERAOLYMPUS DIGITAL CAMERA                                Mimosa nuttalli mixing with grasses in an open field

                                  Spider milkweed growing alongside Sensitive brier

Endangered List- The USDA Plants Conservation site does not have a page showing the Legal Status for Mimosa nuttallii. 

NatureServe lists Mimosa nuttallii as Critically Imperiled in Iowa. Unfortunately, it’s not ranked in nearly all the rest of its habitat, so we cannot know the true conservation status of this interesting plant.

Mimosa nuttallii natureserve status

Interesting Tidbits- Mimosa nuttallii provides forage for deer and turkey. Bobwhite quail consume the seeds and the nectar is important for many insects. It is also nutritious for livestock; although, how they eat the briers, I don’t know. Nevertheless, its absence in a field is a good indicator of overgrazing. The flowers are very attractive to birds, bees and other insects.