North America Native Plant

Interior Phacelia

Botanical name: Phacelia dubia var. interior

USDA symbol: PHDUI

Life cycle: annual

Habit: forb

Native status: Native to the lower 48 states  

Interior Phacelia: A Rare Tennessee Native Worth Discovering If you’re passionate about native plants and love discovering hidden gems, interior phacelia (Phacelia dubia var. interior) might just capture your gardening heart. This charming annual forb represents one of nature’s more elusive treasures, found naturally only in Tennessee. What Makes Interior ...

Rare plant alert!

Region: Conservation status by state

Status: S5T3T4: 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. ⚘ Subspecies or varieties is apparently secure: Uncommon but not rare, and usually widespread. Possibly cause for longterm concern. Typically more than 100 occurrences in the region or more than 10,000 individuals ⚘ 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. ⚘

Interior Phacelia: A Rare Tennessee Native Worth Discovering

If you’re passionate about native plants and love discovering hidden gems, interior phacelia (Phacelia dubia var. interior) might just capture your gardening heart. This charming annual forb represents one of nature’s more elusive treasures, found naturally only in Tennessee.

What Makes Interior Phacelia Special?

Interior phacelia belongs to the waterleaf family and showcases the delicate beauty typical of native Phacelia species. As an annual forb, this herbaceous plant completes its entire life cycle in one growing season, making it a perfect choice for gardeners who enjoy seasonal variety and the excitement of replanting each year.

What sets this variety apart is its extremely limited natural range. Unlike its more widespread relatives, interior phacelia calls only Tennessee home, making it a true regional specialty that connects your garden directly to the unique ecosystems of the Volunteer State.

Geographic Distribution and Native Range

Interior phacelia has one of the most restricted distributions of any native plant in the lower 48 states. This rare variety is endemic to Tennessee, where it has adapted to specific local conditions over thousands of years. Its limited range makes it a botanical treasure that represents the unique biodiversity of Tennessee’s landscapes.

Important Considerations for Gardeners

Before you get too excited about adding this plant to your garden, there’s something crucial to know: interior phacelia carries a Global Conservation Status of S5T3T4. While the exact conservation implications of this status aren’t fully defined, it suggests this variety may face some level of rarity or conservation concern.

If you choose to grow interior phacelia, please ensure you source seeds or plants responsibly. This means:

  • Purchase only from reputable native plant suppliers
  • Never collect seeds or plants from wild populations
  • Choose suppliers who ethically propagate their stock
  • Consider supporting conservation efforts for rare Tennessee plants

Garden Role and Landscape Design

As a native Tennessee forb, interior phacelia would shine in authentic regional gardens, native plant collections, and naturalized areas. Its annual nature makes it ideal for:

  • Native wildflower meadows
  • Seasonal display gardens
  • Educational or conservation-focused landscapes
  • Rain gardens and naturalized areas (where appropriate)

Growing Interior Phacelia

While specific growing information for this rare variety is limited, most Phacelia species share similar preferences. As a Tennessee native, interior phacelia likely thrives in conditions typical of the region’s natural habitats.

Since detailed growing requirements for this specific variety aren’t well-documented, success will likely come from:

  • Observing the plant’s natural habitat preferences
  • Providing well-draining soil
  • Choosing appropriate sun exposure for your region
  • Following general annual flower care practices

The Bottom Line

Interior phacelia represents something special in the native plant world – a rare, regionally-specific variety that connects us to Tennessee’s unique botanical heritage. While growing this plant requires extra responsibility due to its conservation status, it offers the reward of nurturing a truly uncommon native species.

If you’re a dedicated native plant enthusiast in Tennessee or surrounding areas, and you can source this plant responsibly, interior phacelia could become a treasured addition to your collection. Just remember: with rare plants comes the responsibility to protect and preserve them for future generations.

Consider also exploring other native Phacelia species that might be more readily available and equally beneficial to your local ecosystem. Sometimes the most common natives make the biggest impact in supporting local wildlife and pollinators.

Interior Phacelia

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

Solanales

Family

Hydrophyllaceae R. Br. - Waterleaf family

Genus

Phacelia Juss. - phacelia

Species

Phacelia dubia (L.) Trel. - smallflower phacelia

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