prairie peppergrass

(Lepidium densiflorum)

Conservation Status
prairie peppergrass
  IUCN Red List

not listed

     
  NatureServe

NNR - Unranked

SNR - Unranked

     
  Minnesota

not listed

     
           
Wetland Indicator Status
     
  Great Plains

FAC - Facultative

     
  Midwest

FAC - Facultative

     
  Northcentral & Northeast

FACU - Facultative upland

     
           
 
Description
 
 

Prairie peppergrass is a 8 to 20 tall, erect, annual or biennial forb that rises on usually a single stem from a slender, branching taproot.

At first it forms a rosette about 6 in diameter of basal leaves. The basal leaves are 1½ to 2¾ long and either coarsely toothed or untoothed and once lobed. When the plant is a biennial it overwinters in this form. Basal leaves are usually wilted by flowering time.

The flowering stems are erect or ascending. They are occasionally branched at the base, often branched in the upper third. They are covered with minute, straight, spreading hairs.

Lower stem leaves are similar to the basal leaves, alternate, narrowly inversely egg-shaped or linear, 1 to 3 long, and less than wide. They are on short leaf stalks and are sometimes lobed but are usually unlobed. The leaf blades are tapered at the base and taper to a point at the tip with straight sides along the tip. The upper surface is hairless. The lower surface is usually hairless, sometimes sparsely minutely hairy. The margins are usually untoothed.

Upper stem leaves are similar but smaller, linear, and stalkless but not clasping.

The inflorescence is a dense, unbranched cluster (raceme) at the end of the stems and branches. The racemes are compact when in flower, but quickly elongate as the fruits develop, eventually becoming up to 4 long. Typically, a few flowers are in bloom crowded at the top of the raceme, with developing and developed fruits below.

The individual flowers less than wide. There are 4 green, linear to narrowly elliptic sepals, and either 4 white petals or no petals at all. When petals are present they are no longer than the sepals. There is no floral scent.

The fruit is a flattened, 1 16 to long, broadly egg-shaped, seed pod. It is widest above the middle. The tip is narrowly winged and has a broad, shallow notch. It is initially green, turning brownish when dry. It is on a stalk that is spreading or ascending.

 
     
 

Height

 
 

8 to 20

 
     
 

Flower Color

 
 

White petals when present, otherwise green sepals.

 
     
 

Similar Species

 
 

Clasping pepper grass (Lepidium perfoliatum) upper stem leaves are broadly egg-shaped to circular and perfoliate or strongly clasping with auricles that surround the stem and overlap.

Field pennycress (Thlaspi arvense) fruits are much larger, 5 16 to ¾ long, and are broadly winged all around, not just at the tip.

Gardencress pepperweed (Lepidium sativum) fruits are on stalks that are closely ascending or almost erect. The fruits are larger, 3 16 to ¼ wide.

Virginia pepper grass(Lepidium virginicum var. virginicum) is nearly indistinguishable when not in flower. The flowers always have petals. The petals are as long to twice as long as the sepals. The fruits are mostly round, widest at the middle.

 
     
 
Habitat
 
 

Dry to moist. Disturbed sites, roadsides, pastures.

 
     
 
Biology
 
 

Flowering

 
 

May to June

 
     
 

Pests and Diseases

 
 

 

 
     
 

Defense Mechanisms

 
 

This and other mustards (family Brassicaceae) produce chemical compounds when cells are damaged that are toxic to most animals, fungi, and bacteria.

 
     
 
Use
 
 

 

 
     
 
Distribution
 
 

Distribution Map

 

Sources

2, 3, 4, 5, 7, 28, 29, 30.

 
  3/25/2021      
         
 

Nativity

 
 

Native

 
         
 

Occurrence

 
 

Common

 
         
 
Taxonomy
 
  Kingdom Plantae (green algae and land plants)  
  Subkingdom Viridiplantae (green plants)  
  Infrakingdom Streptophyta (land plants and green algae)  
  Superdivision Embryophyta (land plants)  
  Division Tracheophyta (vascular plants)  
  Subdivision Spermatophytina (seed plants)  
  Class Magnoliopsida (dicots)  
  Subclass Rosidae  
  Superorder Rosanae  
 

Order

Brassicales (Mustards, Capers, and Allies)  
 

Family

Brassicaceae (mustard)  
  Tribe Lepidieae  
 

Genus

Lepidium (peppergrass)  
       
 

Subordinate Taxa

 
 

Several varieties of prairie peppergrass have been described. The characteristics used to define these varieties are weak and differ among authors. For these reasons most taxonomists do not recognize any varieties of prairie peppergrass.

 
       
 

Synonyms

 
 

Lepidium densiflorum var. densiflorum

Lepidium densiflorum var. elongatum

Lepidium densiflorum var. macrocarpum

Lepidium densiflorum var. pubecarpum

Lepidium densiflorum var. ramosum

Lepidium densiflorum var. typicum

Lepidium elongatum

Lepidium neglectum

Lepidium pubecarpum

Lepidium ramosum

Lepidium texanum

 
       
 

Common Names

 
 

common peppergrass

common peppergweed

green-flowered peppergrass

miner’s pepperweed

miner’s pepperwort

peppergrass

pepperweed

prairie peppergrass

prairie pepperweed

prairie pepperwort

 
       

 

 

 

 

 

 

 

 

Glossary

Auricle

A small, ear-like projection at the base of a leaf or at the junction of a grass blade and stem.

 

Clasping

Describing a leaf that wholly or partly surrounds the stem but does not fuse at the base.

 

Linear

Long, straight, and narrow, with more or less parallel sides, like a blade of grass.

 

Perfoliate

A leaf having margins that entirely surround the stem, giving the appearance that the stem is growing through the leaf.

 

Raceme

An unbranched, elongated inflorescence with stalked flowers. The flowers mature from the bottom up.

 

 

 

 

       
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Plant

  prairie peppergrass   prairie peppergrass
       

Inflorescence

  prairie peppergrass    
       

Infructescence

  prairie peppergrass   prairie peppergrass
       
       

 

Camera

     
Slideshows
   
  Lepidium campestre FIELD CRESS
Frank Mayfield
 
  Lepidium campestre FIELD CRESS  
     

 

slideshow

       
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MinnesotaSeasons.com Sightings
         

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