- Tall whitetop, Tall pepperweed, Perennial pepperweed, Giant whiteweed, Perennial peppergrass, Slender perennial peppergrass, Broadleaf pepperweed, Ironweed
- Cardaria latifolia
- An herbaceous perennial reaching up to 5 feet tall. Begins as a basal rosette before stem elongation, with basal leaves dying off when top leaves develop. Plant has a horseradish-like taste and odor.
- glaucous (waxy grayish-green)
- glabrous, sometimes hairy
- basal rosette leaves 11.8 inches long and 3 inches wide
- 1.2-6 inches long petioles
- Stem leaves alternate, sessile, reduced
- tapering at base
- lanceolate to elliptic or oblong
- entire or weakly toothed margins
- glabrous (smooth), sometimes hairy
- White flowers with four ovate petals and four small, green, oval sepals. Each flower contains six stamens with a single pistil. Blooms from early summer through most of growing season.
- small 0.08 inches
- round capsule (silicle), green to brown
- one reddish-brown, slightly flattened seed per chamber
- fruits produced in late summer and fall
- coastal beaches, dunes or grasslands
- New England infestations are mainly found near coastal areas, especially above the high tide line at the upper edges of salt marshes
- also occurs in disturbed or mowed areas far from coastal areas, abandoned fields, roadsides, and vacant lots
- seeds mechanically or wind-dispersed
- animals, humans or vehicles can disperse by coming into contact with the plant
- also reproduces vegetatively by rhizomes
Key ID Features:
- 4 white petals
- plant has horseradish taste and odor
- waxy grayish-green leaves and stems
- basal rosette leaves toothed
- stem leaves alternate and sessile
- Hoary cress (Cardaria draba), Lens-podded whitetop (C. chalepensis) and Hairy whitetop (C. pubescens) are similar to this species, since they all have creeping roots and are all noxious perennial weeds, but they have hairy foliage. Cardaria also typically have pods that are more than 2mm long, appear inflated and have persistant styles.
- Field pepperweed (Lepidium campestre) and Clasping pepperweed (L. perfoliatum) are similar but flower in long racemes, while Tall pepperweed inflorescences are rounded umbels.
- Can form dense stands that increase over time
- Can out-compete native species within these habitats
- Tall pepperweed is common in coastal habitats on the New England coast, but is not restricted to these habitats.
- While this species is not known on Nantucket as of December 2006, it is a salt-tolerant invader that is already known along most of the Massachusetts coast and several Boston Harbor islands. Please report any potential sightings of this species.
Growth Form: Herb
Origin: Southeast Europe, North Africa, Southwest Asia
Level of Invasiveness for Nantucket: Potential Invasive
Level of Invasiveness for Massachusetts: Invasive
Massachusetts Cultivation Restrictions: importation ban, propagation ban