North America Native Plant

Onesided Threadplant

Botanical name: Nemacladus secundiflorus

USDA symbol: NESE

Life cycle: annual

Habit: forb

Native status: Native to the lower 48 states  

Onesided Threadplant: A Rare California Native for Specialized Gardens Meet the onesided threadplant (Nemacladus secundiflorus), one of California’s most delicate and uncommon native wildflowers. This tiny annual might not win any beauty contests against showier native plants, but it holds a special place in the hearts of native plant enthusiasts ...

Rare plant alert!

Region: Conservation status by state

Status: S3: 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 ⚘

Onesided Threadplant: A Rare California Native for Specialized Gardens

Meet the onesided threadplant (Nemacladus secundiflorus), one of California’s most delicate and uncommon native wildflowers. This tiny annual might not win any beauty contests against showier native plants, but it holds a special place in the hearts of native plant enthusiasts and desert gardening aficionados.

What Makes Onesided Threadplant Special?

The onesided threadplant is a diminutive forb—essentially a small, non-woody flowering plant—that epitomizes the phrase good things come in small packages. This annual produces thread-like stems topped with tiny white to pale pink flowers that bloom along just one side of the stem, hence its descriptive common name.

As a native species exclusive to California, this plant represents the unique botanical heritage of the Golden State’s desert regions. However, there’s an important caveat every gardener should know: onesided threadplant has a Global Conservation Status of S3, meaning it’s considered vulnerable in the wild.

Where Does It Grow Naturally?

Onesided threadplant is endemic to California, where it thrives in the state’s desert environments. You’ll find this rare beauty in sandy washes, rocky slopes, and other well-draining desert habitats throughout Southern California’s arid regions.

Should You Grow Onesided Threadplant?

The short answer: Only if you’re a dedicated native plant gardener with the right conditions and access to responsibly sourced seeds or plants. Here’s why:

  • Rarity concerns: With its vulnerable conservation status, it’s crucial to source this plant only from reputable native plant nurseries or seed companies that collect sustainably
  • Specialized growing requirements: This isn’t a plant for beginners or typical garden settings
  • Limited aesthetic impact: Its tiny flowers and delicate structure make it more of a botanical curiosity than a landscape showstopper
  • Perfect for the right garden: If you’re creating a desert native garden or rock garden in appropriate climate zones, this could be a meaningful addition

Growing Conditions and Care

Onesided threadplant is definitely not your typical garden annual. Success requires mimicking its natural desert habitat:

Climate: Best suited for USDA hardiness zones 9-11, particularly in areas with hot, dry summers and mild winters.

Soil: The key to success is excellent drainage. Think sandy, rocky, or gravelly soils that drain quickly after any moisture. Heavy clay or water-retentive soils will likely kill this desert native.

Water: Once established, this plant thrives on minimal water. Overwatering is probably the fastest way to lose it. Natural rainfall in its native habitat is typically sufficient.

Sun exposure: Full sun is essential—this plant evolved in open desert conditions with intense sunlight.

Planting and Propagation Tips

Since onesided threadplant is an annual, you’ll need to replant each year or allow it to self-seed:

  • Timing: Plant seeds in fall or early winter to align with natural germination patterns
  • Method: Direct seeding is preferred, as the delicate roots don’t transplant well
  • Spacing: Given its tiny size, plant seeds close together for visual impact
  • Patience required: Germination can be sporadic and may require specific temperature and moisture conditions

Garden Design Role

Think of onesided threadplant as a botanical accent piece rather than a garden workhorse. It works beautifully in:

  • Desert-themed rock gardens
  • Native plant collections
  • Containers with other small desert annuals
  • Spaces between larger desert plants where its delicate texture provides contrast

Wildlife and Pollinator Benefits

While small, onesided threadplant does provide nectar for tiny native bees and other small pollinators. Its role in the ecosystem may be modest, but every native plant contributes to supporting local wildlife communities.

The Bottom Line

Onesided threadplant isn’t for everyone, and that’s okay. This rare California native is best suited for dedicated native plant gardeners who appreciate subtle beauty and want to support conservation through cultivation. If you’re drawn to this unique little plant, make sure to source it responsibly and provide the specialized care it needs to thrive.

For most gardeners interested in California natives, consider starting with more readily available and garden-friendly options before tackling this delicate beauty. But if you’re up for the challenge and have the right growing conditions, onesided threadplant could be a meaningful addition to your native plant collection.

Onesided Threadplant

Classification

Group

Dicot

Kingdom

Plantae - Plants

Subkingdom

Tracheobionta - Vascular plants

Superdivision

Spermatophyta - Seed plants

Division

Magnoliophyta - Flowering plants

Subdivision
Class

Magnoliopsida - Dicotyledons

Subclass

Asteridae

Order

Campanulales

Family

Campanulaceae Juss. - Bellflower family

Genus

Nemacladus Nutt. - threadplant

Species

Nemacladus secundiflorus G.T. Robbins - onesided threadplant

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