North America Native Plant

Isle-of-pines Crabgrass

Botanical name: Digitaria simpsonii

USDA symbol: DISI

Life cycle: annual

Habit: grass

Native status: Native to the lower 48 states  

Synonyms: Syntherisma simpsonii (Vasey) Nash (SYSI)   

Isle-of-Pines Crabgrass: A Rare Florida Native Worth Protecting Meet one of Florida’s most endangered grasses – the Isle-of-Pines crabgrass (Digitaria simpsonii). Don’t let the crabgrass name fool you into thinking this is just another weedy pest. This delicate annual grass is actually a botanical treasure that’s fighting for survival in ...

Rare plant alert!

Region: Conservation status by state

Status: S2: Status is uncertain but is somewhere between the following rankings: Imperiled: Extremely rare due to factor(s) making it especially vulnerable to extinction. Typically 6 to 20 occurrences or few remaining individuals (1,000 to 3,000) ⚘

Isle-of-Pines Crabgrass: A Rare Florida Native Worth Protecting

Meet one of Florida’s most endangered grasses – the Isle-of-Pines crabgrass (Digitaria simpsonii). Don’t let the crabgrass name fool you into thinking this is just another weedy pest. This delicate annual grass is actually a botanical treasure that’s fighting for survival in the Sunshine State.

What Makes Isle-of-Pines Crabgrass Special?

Isle-of-Pines crabgrass is a fine-textured annual grass that’s as rare as it is beautiful. Also known scientifically as Digitaria simpsonii (and formerly called Syntherisma simpsonii), this Florida endemic has earned a sobering conservation status of S2, meaning it’s imperiled with only 6 to 20 known occurrences remaining in the wild.

Unlike its weedy relatives, this native crabgrass plays an important role in Florida’s unique ecosystems, particularly in sandy coastal areas and pine rocklands where it has evolved over thousands of years.

Where Does It Call Home?

This grass is found exclusively in Florida, making it a true Floridian native. Its natural habitat includes the state’s sandy coastal regions and specialized pine rockland ecosystems, where it has adapted to thrive in challenging conditions that would stress many other plants.

Should You Grow Isle-of-Pines Crabgrass?

Here’s the important part: Due to its imperiled status, this grass should only be grown using responsibly sourced material from reputable native plant nurseries or seed suppliers. Never collect seeds or plants from wild populations, as this could further harm already vulnerable communities.

That said, there are compelling reasons to consider this rare beauty:

  • Support conservation efforts by growing a piece of Florida’s natural heritage
  • Perfect for specialized restoration projects in coastal or pine rockland areas
  • Adds authentic Florida character to native plant gardens
  • Helps maintain genetic diversity of this endangered species

Growing Conditions and Care

Isle-of-Pines crabgrass is quite particular about its growing conditions, which partly explains its rarity:

  • Soil: Sandy, well-drained soils that mimic its coastal native habitat
  • Sun: Full sun exposure
  • Water: Moderate moisture; avoid waterlogged conditions
  • Climate: Thrives in USDA zones 9b-11 (South Florida conditions)
  • Salt tolerance: Can handle some salt spray, making it suitable for coastal gardens

Planting and Maintenance Tips

Growing this rare grass successfully requires attention to detail:

  • Start from seed in fall when temperatures begin to cool
  • Prepare sandy, well-draining soil similar to its natural pine rockland habitat
  • Scatter seeds lightly and barely cover with sand
  • Keep soil consistently moist until germination
  • Once established, this annual will self-seed under ideal conditions
  • Minimal fertilization needed – too much nutrition can actually harm native grasses

Garden Design and Landscape Use

Isle-of-Pines crabgrass works best in specialized settings:

  • Native Florida plant collections
  • Coastal restoration projects
  • Educational gardens showcasing rare species
  • Pine rockland habitat reconstructions
  • Areas where you want to support biodiversity conservation

Wildlife and Ecological Benefits

While this grass may seem inconspicuous, it likely provides important ecological services in its native habitat, including soil stabilization and serving as part of the complex web of native plant communities that support Florida’s unique wildlife.

A Word of Caution and Hope

Growing Isle-of-Pines crabgrass is more than just gardening – it’s conservation in action. With only 6 to 20 wild populations remaining, every responsibly grown plant helps preserve this species for future generations. If you’re interested in growing this rare native, work with reputable native plant societies, botanical gardens, or specialized nurseries that can provide ethically sourced material.

Remember: protecting our rarest native plants requires both respect for wild populations and commitment to growing them responsibly in our gardens. Isle-of-Pines crabgrass may be small and humble, but it represents something irreplaceable – a living piece of Florida’s natural heritage that deserves our protection.

Isle-of-pines Crabgrass

Classification

Group

Monocot

Kingdom

Plantae - Plants

Subkingdom

Tracheobionta - Vascular plants

Superdivision

Spermatophyta - Seed plants

Division

Magnoliophyta - Flowering plants

Subdivision
Class

Liliopsida - Monocotyledons

Subclass

Commelinidae

Order

Cyperales

Family

Poaceae Barnhart - Grass family

Genus

Digitaria Haller - crabgrass

Species

Digitaria simpsonii (Vasey) Fernald - Isle-of-Pines crabgrass

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