North America Native Plant

Curtiss’ Loosestrife

Botanical name: Lythrum curtissii

USDA symbol: LYCU2

Life cycle: perennial

Habit: subshrub

Native status: Native to the lower 48 states  

Curtiss’ Loosestrife: A Rare Wetland Treasure That Needs Our Protection Meet Curtiss’ loosestrife (Lythrum curtissii), one of the Southeast’s most endangered native wildflowers. This tiny perennial herb might not look like much, but it’s fighting for survival in the wetlands of Florida and Georgia. Before you even think about adding ...

Rare plant alert!

Region: Conservation status by state

Status: S1: Status is uncertain but is somewhere between the following rankings: 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) ⚘

Curtiss’ Loosestrife: A Rare Wetland Treasure That Needs Our Protection

Meet Curtiss’ loosestrife (Lythrum curtissii), one of the Southeast’s most endangered native wildflowers. This tiny perennial herb might not look like much, but it’s fighting for survival in the wetlands of Florida and Georgia. Before you even think about adding this plant to your garden, there’s something crucial you need to know about its conservation status.

A Plant on the Brink

Here’s the reality check: Curtiss’ loosestrife has a Global Conservation Status of S1, meaning it’s critically imperiled. We’re talking about fewer than five known locations and less than 1,000 individual plants remaining in the wild. This isn’t just rare – it’s teetering on the edge of extinction.

Important Conservation Note: Due to its critically endangered status, we strongly recommend against attempting to grow Curtiss’ loosestrife unless you’re working with conservation organizations and have access to ethically sourced, propagated material. Wild collection could push this species over the brink.

Where Does It Call Home?

This native wildflower is found exclusively in the southeastern United States, with its remaining populations scattered across Florida and Georgia. As an obligate wetland species, it depends entirely on wetland habitats that are constantly moist to saturated.

What Makes It Special?

Curtiss’ loosestrife is a perennial forb – essentially a non-woody herbaceous plant that comes back year after year. Like other members of the Lythrum family, it likely produces small, delicate purple-pink flowers that would be quite charming if you could actually see them in the wild (which, given their rarity, is extremely unlikely).

As an obligate wetland plant, this species has adapted to life in constantly wet conditions. Its entire existence revolves around specialized wetland ecosystems that are themselves under threat from development and climate change.

Growing Conditions (For Conservation Purposes Only)

If you’re involved in legitimate conservation efforts, here’s what Curtiss’ loosestrife needs:

  • Moisture: Obligate wetland conditions – think constantly saturated soils
  • Climate: Likely hardy in USDA zones 8-10, based on its Florida and Georgia distribution
  • Habitat: Specialized wetland ecosystems with very specific water chemistry and soil conditions
  • Care: Extremely challenging due to precise habitat requirements

Why You Shouldn’t Grow It (And What to Plant Instead)

Unless you’re a botanical garden, research institution, or conservation organization with proper permits and expertise, please don’t attempt to grow Curtiss’ loosestrife. Here’s why:

  • Wild collection could eliminate entire populations
  • It requires extremely specialized growing conditions that are nearly impossible to replicate in home gardens
  • There are many other beautiful native wetland plants that aren’t endangered

Better Native Alternatives for Wetland Gardens

Want to support native wetland plants without risking an endangered species? Try these gorgeous alternatives:

  • Blue flag iris (Iris virginica): Stunning purple-blue flowers, much easier to grow
  • Cardinal flower (Lobelia cardinalis): Brilliant red spikes that hummingbirds adore
  • Swamp milkweed (Asclepias incarnata): Pink clusters that support monarch butterflies
  • Pickerelweed (Pontederia cordata): Purple flower spikes with heart-shaped leaves

How You Can Help

The best thing you can do for Curtiss’ loosestrife is to protect its remaining habitat. Support wetland conservation organizations, avoid disturbing natural wetlands, and spread awareness about this critically endangered species. Sometimes the most loving thing we can do for a rare plant is to leave it alone and protect the places where it still grows.

Remember, every extinct plant is a library burned down. Let’s make sure Curtiss’ loosestrife doesn’t become just a memory in botanical texts.

Curtiss’ Loosestrife

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

Myrtales

Family

Lythraceae J. St.-Hil. - Loosestrife family

Genus

Lythrum L. - loosestrife

Species

Lythrum curtissii Fernald - Curtiss' loosestrife

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