North America Native Plant

Thickleaf Pepperweed

Botanical name: Lepidium integrifolium var. integrifolium

USDA symbol: LEINI

Life cycle: biennial

Habit: subshrub

Native status: Native to the lower 48 states  

Synonyms: Lepidium campestre (L.) W.T. Aiton var. integrifolium (Nutt.) C.L. Hitchc. (LECAI)  âš˜  Lepidium montanum Nutt. var. integrifolium (Nutt.) C.L. Hitchc. (LEMOI)   

Thickleaf Pepperweed: A Rare Native Worth Knowing About Meet thickleaf pepperweed (Lepidium integrifolium var. integrifolium), a lesser-known native plant that’s quietly making its home in the American West. This unassuming member of the mustard family might not be the showiest plant in your garden, but it carries the important distinction ...

Rare plant alert!

Region: Conservation status by state

Status: S2S3T2T3: 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) ⚘ Subspecies or variety is 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) ⚘ 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 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. ⚘

Thickleaf Pepperweed: A Rare Native Worth Knowing About

Meet thickleaf pepperweed (Lepidium integrifolium var. integrifolium), a lesser-known native plant that’s quietly making its home in the American West. This unassuming member of the mustard family might not be the showiest plant in your garden, but it carries the important distinction of being a true native with an interesting story to tell.

Where You’ll Find This Native Gem

Thickleaf pepperweed is native to the lower 48 states, though it keeps a relatively low profile with a limited geographic range. You’ll find this hardy little plant naturally occurring in Arizona, Utah, and Wyoming, where it has adapted to the challenging conditions of the American Southwest and Mountain West.

What Makes This Plant Special

As a forb (that’s botanist-speak for a non-woody flowering plant), thickleaf pepperweed grows as a biennial or perennial herb. Like other members of its family, it lacks significant woody tissue and keeps its growing points at or below ground level – a smart strategy for surviving harsh winters and dry summers.

This plant also goes by a couple of scientific aliases, including Lepidium campestre var. integrifolium and Lepidium montanum var. integrifolium, which you might encounter in older botanical references.

A Word About Rarity

Here’s where things get important: thickleaf pepperweed has a conservation status that suggests it’s uncommon to rare in its native range. This means if you’re interested in growing this plant, you’ll want to be extra careful about sourcing. Never collect from wild populations, and always purchase from reputable native plant nurseries that practice ethical propagation methods.

Should You Grow Thickleaf Pepperweed?

The honest answer is: it depends on your goals and location. Here are some considerations:

  • For native plant enthusiasts: If you’re in Arizona, Utah, or Wyoming and passionate about growing truly local species, this could be a meaningful addition to your collection
  • For general gardeners: With limited information available about its garden performance and ornamental value, you might want to consider more well-documented native alternatives
  • For conservation-minded gardeners: Growing rare natives from responsibly sourced material can contribute to conservation efforts

The Growing Challenge

Here’s where we hit a bit of a roadblock: specific growing information for this particular variety is quite limited in available resources. As a native of the Southwest and Mountain West, it likely prefers:

  • Well-draining soils (most desert and semi-arid natives do)
  • Full sun to partial shade
  • Low to moderate water once established
  • USDA hardiness zones that match its native range (likely zones 4-8)

However, without detailed cultivation studies, these are educated guesses based on its native habitat and plant family characteristics.

Consider These Alternatives

If you’re drawn to the idea of growing native pepperweed species but want more reliable growing information, consider researching other Lepidium species native to your area. Many states have their own native members of this genus with better-documented cultivation requirements.

The Bottom Line

Thickleaf pepperweed represents the fascinating world of lesser-known native plants – species that play important roles in their ecosystems but haven’t yet made it into mainstream gardening. While it might not be the easiest plant to grow or find, it offers dedicated native plant gardeners a chance to connect with truly local flora.

If you decide to seek out this plant, remember to source responsibly and consider it an experiment in growing rare natives. And who knows? You might just become one of the few gardeners helping to preserve this uncommon piece of American botanical heritage.

Thickleaf Pepperweed

Classification

Group

Dicot

Kingdom

Plantae - Plants

Subkingdom

Tracheobionta - Vascular plants

Superdivision

Spermatophyta - Seed plants

Division

Magnoliophyta - Flowering plants

Subdivision
Class

Magnoliopsida - Dicotyledons

Subclass

Dilleniidae

Order

Capparales

Family

Brassicaceae Burnett - Mustard family

Genus

Lepidium L. - pepperweed

Species

Lepidium integrifolium Nutt. - thickleaf pepperweed

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