North America Native Plant

Mearns’ Bird’s-foot Trefoil

Botanical name: Lotus mearnsii var. mearnsii

USDA symbol: LOMEM

Life cycle: perennial

Habit: forb

Native status: Native to the lower 48 states  

Mearns’ Bird’s-Foot Trefoil: A Rare Arizona Native Worth Knowing If you’re passionate about native plants and love discovering botanical treasures, Mearns’ bird’s-foot trefoil (Lotus mearnsii var. mearnsii) might just capture your interest. This little-known perennial forb represents one of Arizona’s more elusive native wildflowers, and while information about it is ...

Rare plant alert!

Region: Conservation status by state

Status: S3T3: Status is uncertain but is somewhere between the following rankings: Vulnerable: Either very rare and local throughout its range, found only in a restricted range (even if abundant at some locations), or factors are making it vulnerable to extinction. Typically 21 to 100 occurrences or between 3,000 and 10,000 individuals ⚘ Subspecies or variety is vulnerable: Either very rare and local throughout its range, found only in a restricted range (even if abundant at some locations), or factors are making it vulnerable to extinction. Typically 21 to 100 occurrences or between 3,000 and 10,000 individuals. ⚘

Mearns’ Bird’s-Foot Trefoil: A Rare Arizona Native Worth Knowing

If you’re passionate about native plants and love discovering botanical treasures, Mearns’ bird’s-foot trefoil (Lotus mearnsii var. mearnsii) might just capture your interest. This little-known perennial forb represents one of Arizona’s more elusive native wildflowers, and while information about it is surprisingly scarce, its rarity makes it all the more intriguing for dedicated native plant enthusiasts.

A True Arizona Native

Mearns’ bird’s-foot trefoil is authentically native to the United States, specifically calling Arizona home. As a member of the legume family, this herbaceous perennial adds to Arizona’s impressive diversity of native wildflowers. Unlike many plants that have spread across multiple states, this particular variety appears to be quite specialized in its geographic preferences.

What Makes This Plant Special

As a forb—essentially a non-woody flowering plant—Mearns’ bird’s-foot trefoil grows as a perennial, meaning it returns year after year once established. Like other members of the bird’s-foot trefoil family, it likely produces small, pea-like flowers typical of legumes, though specific details about its appearance remain surprisingly elusive in botanical literature.

The Rarity Factor: Why This Matters

Here’s where things get interesting (and important): Lotus mearnsii var. mearnsii carries a conservation status of S3T3. While the exact definition of this rating isn’t clearly specified, conservation codes in this range typically indicate plants that may be uncommon or vulnerable. This rarity status means that if you’re considering adding this plant to your garden, responsible sourcing is absolutely crucial.

  • Never collect plants from wild populations
  • Only purchase from reputable native plant nurseries
  • Verify that any plants you buy were propagated, not wild-collected
  • Consider growing it as part of conservation efforts

Growing Mearns’ Bird’s-Foot Trefoil

Unfortunately, detailed growing information for this specific variety is limited, which isn’t uncommon for rare native plants that haven’t made their way into mainstream horticulture. However, as an Arizona native forb, it likely adapted to the state’s challenging growing conditions, including:

  • Tolerance for arid conditions
  • Adaptation to alkaline soils
  • Resistance to temperature extremes
  • Minimal water requirements once established

Should You Grow It?

If you’re a native plant enthusiast in Arizona with a passion for conservation, Mearns’ bird’s-foot trefoil could be a meaningful addition to your garden—but only if you can source it responsibly. The plant’s rarity makes it more of a conservation project than a typical landscaping choice.

Consider this plant if you:

  • Want to support native plant conservation
  • Enjoy growing uncommon or rare species
  • Have experience with challenging or unusual plants
  • Can commit to proper care and potentially seed collection for conservation

The Bottom Line

Mearns’ bird’s-foot trefoil represents one of those fascinating botanical mysteries—a native plant that seems to fly under the radar despite its legitimate place in Arizona’s natural heritage. While the limited information available makes it challenging to provide detailed growing advice, its native status and apparent rarity make it worthy of conservation attention.

If you’re drawn to this unique native, connect with local native plant societies, botanical gardens, or conservation organizations. They may have more insights about this elusive Arizona native and can help you source it responsibly if it becomes available. Sometimes the most rewarding garden plants are the ones that challenge us to become better stewards of our native flora.

Mearns’ Bird’s-foot Trefoil

Classification

Group

Dicot

Kingdom

Plantae - Plants

Subkingdom

Tracheobionta - Vascular plants

Superdivision

Spermatophyta - Seed plants

Division

Magnoliophyta - Flowering plants

Subdivision
Class

Magnoliopsida - Dicotyledons

Subclass

Rosidae

Order

Fabales

Family

Fabaceae Lindl. - Pea family

Genus

Lotus L. - trefoil

Species

Lotus mearnsii (Britton) Greene - Mearns' bird's-foot trefoil

Plant data source: USDA, NRCS 2025. The PLANTS Database. https://plants.usda.gov,. 2/25/2025. National Plant Data Team, Greensboro, NC USA