North America Native Plant

Rattan’s Milkvetch

Botanical name: Astragalus rattanii var. rattanii

USDA symbol: ASRAR3

Life cycle: annual

Habit: forb

Native status: Native to the lower 48 states  

Rattan’s Milkvetch: A Small California Native with Big Conservation Value If you’re passionate about growing truly native California plants, you might want to get acquainted with Rattan’s milkvetch (Astragalus rattanii var. rattanii). This modest annual legume may not win any beauty contests, but it’s got something special that makes it ...

Rare plant alert!

Region: Conservation status by state

Status: S4T3: Status is uncertain but is somewhere between the following rankings: 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. ⚘ Apparently Secure: Uncommon but not rare, and usually widespread. Possibly cause for longterm concern. Typically more than 100 occurrences in the state or more than 10,000 individuals ⚘

Rattan’s Milkvetch: A Small California Native with Big Conservation Value

If you’re passionate about growing truly native California plants, you might want to get acquainted with Rattan’s milkvetch (Astragalus rattanii var. rattanii). This modest annual legume may not win any beauty contests, but it’s got something special that makes it worth considering for your native plant garden: it’s a genuine California original that plays an important role in the state’s natural ecosystems.

What Makes Rattan’s Milkvetch Special?

Rattan’s milkvetch is an annual plant, which means it completes its entire life cycle in just one growing season. As a member of the legume family, it has the superpower of fixing nitrogen in the soil, essentially fertilizing itself and its neighbors. This little plant is exclusively native to California, making it a true Golden State endemic.

The plant produces small, pea-like flowers typical of the Astragalus genus. While it won’t provide the showy blooms of some native wildflowers, it has its own quiet charm and serves as an important piece of California’s botanical puzzle.

Where Does It Grow?

You’ll only find Rattan’s milkvetch growing naturally in California, where it has adapted to the state’s unique Mediterranean climate and soil conditions. Its limited geographic range makes it particularly valuable for gardeners interested in supporting local biodiversity.

Should You Grow Rattan’s Milkvetch?

Here’s where things get interesting – and a bit cautious. This plant appears to have a conservation status that suggests it may be somewhat rare or restricted in its natural range. If you’re considering adding it to your garden, here are some important points to consider:

  • Conservation value: Growing rare natives can help preserve genetic diversity and support conservation efforts
  • Responsible sourcing: Only obtain seeds or plants from reputable native plant nurseries that source material ethically
  • Specialized interest: This is more of a plant geek choice than a mainstream garden addition
  • Educational value: Perfect for botanical gardens, school gardens, or conservation-focused landscapes

Growing Rattan’s Milkvetch Successfully

Since this is an annual plant adapted to California’s climate, successful cultivation requires understanding its natural growing patterns:

Climate and Hardiness

Rattan’s milkvetch is best suited for USDA zones 8-10, thriving in California’s Mediterranean climate with its wet winters and dry summers.

Soil and Water Requirements

Like most California natives, this plant likely prefers well-draining soils and can tolerate drought conditions once established. Avoid overwatering, especially during the summer months.

Planting and Care Tips

  • Start from seed in fall or early winter to mimic natural growing patterns
  • Choose a location with good drainage to prevent root rot
  • Provide minimal supplemental water once established
  • Allow plants to go to seed to maintain the population in your garden
  • Be patient – as an annual, you’ll need to wait for natural reseeding or replant each year

Wildlife and Pollinator Benefits

While small, Rattan’s milkvetch likely provides nectar and pollen for native bees and other small pollinators. As a legume, it also contributes to soil health by fixing nitrogen, benefiting the entire plant community around it.

The Bottom Line

Rattan’s milkvetch isn’t for every gardener, but it’s perfect for those who want to grow something truly special and support California’s native plant heritage. If you’re interested in conservation, love rare plants, or want to create a landscape that tells the story of California’s unique botanical diversity, this little legume deserves a spot in your garden.

Just remember: if you decide to grow it, source your seeds responsibly and consider yourself a steward of this special piece of California’s natural heritage. Sometimes the smallest plants make the biggest difference in conservation efforts.

Rattan’s Milkvetch

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

Astragalus L. - milkvetch

Species

Astragalus rattanii A. Gray - Rattan's milkvetch

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