North America Native Plant

Santa Cruz Island Silverhosackia

Botanical name: Lotus argophyllus var. adsurgens

USDA symbol: LOARA5

Life cycle: perennial

Habit: forb

Native status: Native to the lower 48 states  

Synonyms: Lotus argophyllus (A. Gray) Greene ssp. adsurgens (Dunkle) P.H. Raven (LOARA)   

Santa Cruz Island Silverhosackia: A Rare California Native Worth Protecting Meet one of California’s most exclusive native plants: the Santa Cruz Island silverhosackia (Lotus argophyllus var. adsurgens). This perennial forb is so special that it’s found nowhere else in the world except California, making it a true Golden State gem ...

Rare plant alert!

Region: Conservation status by state

Status: S5T1: Status is uncertain but is somewhere between the following rankings: Subspecies or variety is critically Imperiled: Extremely rare due to factor(s) making it especially vulnerable to extinction. Typically 5 or fewer occurrences or very few remaining individuals (<1,000) ⚘ Secure: At very low or no risk of extinction in the jurisdiction due to a very extensive range, abundant populations or occurrences, with little to no concern from declines or threats. ⚘

Santa Cruz Island Silverhosackia: A Rare California Native Worth Protecting

Meet one of California’s most exclusive native plants: the Santa Cruz Island silverhosackia (Lotus argophyllus var. adsurgens). This perennial forb is so special that it’s found nowhere else in the world except California, making it a true Golden State gem for native plant enthusiasts who appreciate botanical rarities.

What Makes This Plant Special?

The Santa Cruz Island silverhosackia belongs to the pea family and grows as a herbaceous perennial forb. Unlike woody shrubs or trees, this plant lacks significant woody tissue above ground, instead producing soft stems and foliage that die back seasonally while the root system persists year after year.

As its name suggests, this variety is closely associated with California’s Channel Islands ecosystem, representing a unique evolutionary adaptation to island conditions.

Where Does It Grow?

This native plant is exclusively found in California, making it a true endemic species. Its limited geographical distribution contributes to its conservation significance.

A Word of Caution: Rarity Matters

Here’s something every responsible gardener needs to know: Santa Cruz Island silverhosackia has a Global Conservation Status of S5T1, indicating it’s extremely rare. This means if you’re interested in growing this plant, you must only source it from reputable native plant nurseries that propagate their own stock responsibly.

Never collect seeds or plants from wild populations. Instead, support conservation efforts by purchasing only nursery-propagated specimens and ensuring your source follows ethical collection practices.

Why Grow Santa Cruz Island Silverhosackia?

Despite limited information about its specific garden performance, there are compelling reasons to consider this rare native:

  • Conservation value: Growing rare natives helps preserve genetic diversity
  • True California heritage: Support authentic local ecosystems
  • Perennial reliability: Returns each year once established
  • Conversation starter: Few plants have such an exclusive story

Growing Conditions and Care

Unfortunately, specific growing requirements for Santa Cruz Island silverhosackia aren’t well-documented in readily available sources. However, as a California Channel Islands native, it likely prefers:

  • Mediterranean climate conditions
  • Well-draining soils
  • Protection from harsh inland heat
  • Moderate water during establishment

Given its rarity, we recommend consulting with specialized California native plant societies or botanical gardens for specific cultivation advice before attempting to grow this variety.

The Bottom Line

Santa Cruz Island silverhosackia represents the kind of botanical treasure that makes California’s native flora so remarkable. While information about its garden performance is limited, its conservation value alone makes it worthy of consideration for dedicated native plant gardeners.

If you decide to grow this rare beauty, remember: source responsibly, grow with care, and appreciate the privilege of nurturing one of California’s most exclusive native plants. Your garden could become a small sanctuary for a species that exists nowhere else on Earth.

Consider connecting with local native plant societies, botanical gardens, or Channel Islands specialists who might offer guidance on successfully cultivating this remarkable island endemic.

Santa Cruz Island Silverhosackia

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 argophyllus (A. Gray) Greene - silver 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