North America Non-native Plant

Mammoth Wildrye

Botanical name: Leymus racemosus sabulosus

USDA symbol: LERAS

Habit: grass

Native status: Not native but doesn't reproduce and persist in the wild

Synonyms: Elymus sabulosus M. Bieb. (ELSA5)   

Mammoth Wildrye: The Mysterious Grass That’s Hard to Pin Down Ever stumbled across a plant name that seems to exist in a botanical twilight zone? Meet mammoth wildrye (Leymus racemosus sabulosus), a grass species that’s more enigmatic than your average lawn inhabitant. While its name suggests something grand and substantial, ...

Mammoth Wildrye: The Mysterious Grass That’s Hard to Pin Down

Ever stumbled across a plant name that seems to exist in a botanical twilight zone? Meet mammoth wildrye (Leymus racemosus sabulosus), a grass species that’s more enigmatic than your average lawn inhabitant. While its name suggests something grand and substantial, this particular plant is surprisingly elusive in the gardening world.

What We Do Know

Mammoth wildrye belongs to the grass family (Poaceae) and falls under the broader category of grasses and grass-like plants. You might also see it referenced by its botanical synonym Elymus sabulosus M. Bieb., which gives us a hint that this plant has had some taxonomic shuffling in its past—always a sign of a plant that keeps botanists on their toes!

As a member of the Leymus genus, this species would theoretically share some characteristics with its better-known relatives, which are typically hardy, clumping grasses. However, specific details about mammoth wildrye’s appearance, growth habits, and garden performance remain frustratingly scarce.

The Information Gap

Here’s where things get interesting (and a bit frustrating for us plant enthusiasts): reliable information about Leymus racemosus sabulosus is remarkably limited. We don’t have clear data on:

  • Its native range and geographic distribution
  • Specific growing conditions and care requirements
  • USDA hardiness zones
  • Wildlife and pollinator benefits
  • Whether it’s considered invasive or beneficial in garden settings

Should You Plant It?

Given the lack of available information about mammoth wildrye’s growing requirements, native status, and potential impacts, it’s difficult to make a solid recommendation either way. This uncertainty is actually pretty common with lesser-known or potentially misidentified plant species.

If you’re considering adding this grass to your landscape, you might want to explore better-documented Leymus species instead. Many wildrye grasses in this genus are excellent choices for native gardens, offering drought tolerance, wildlife habitat, and attractive seed heads that add movement to the landscape.

The Bottom Line

Mammoth wildrye represents one of those botanical mysteries that remind us how much we still don’t know about the plant kingdom. While its name certainly sounds impressive, the lack of reliable growing information makes it a risky choice for most gardeners.

If you’re drawn to wildrye grasses in general, consider researching well-documented species in your area that can provide similar aesthetic benefits with the confidence that comes from proven garden performance. Sometimes the best plant choices are the ones we can actually find reliable information about!

Have you encountered this mysterious mammoth wildrye in your gardening adventures? We’d love to hear about your experiences with this elusive grass.

Mammoth Wildrye

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

Leymus Hochst. - wildrye

Species

Leymus racemosus (Lam.) Tzvelev - mammoth wildrye

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