Family: Plantaginaceae

Foxglove (Digitalis purpurea) is an invasive forb that spreads from initial plantings. It was recently discovered growing on the edge of a critical conservation zone on the Big Island. As a bi-annual, foxglove begins life as just a small rosette of fuzzy leaves until the second year when the massive stalk rises and profusely blooms. While in the rosette stage, the population can go unnoticed. This was likely the case with this population: the plant went unnoticed or had not germinated yet during previous plant surveys, keeping it off the radar until botanists happened upon the plant during flowering season in a lucky break. This white flower was obviously out of place and raised the alarm!

Foxglove had not been documented as naturalized anywhere in the state. However, it has been cultivated in Hawaii as far back as 1948. Somehow, it made its way to a native forested area far from residential homes after all those years. Although close by was a patch of ground bulldozed more than four years prior, it was unknown how the foxglove got there. It is a BIISC eradication species.

Description and Dispersal:

• An herbaceous perennial with a rosette of fuzzy leaves
  
• The flowering stem can extend upwards to 1-2m from the base of the plant
  
• Flowering begins in the second year of life
  
• The flowers are tubular, pendent shaped, and can come in various colors including purple, pink, yellow, and white.
  
• The fruit is a capsule that splits open and disperses numerous tiny seeds

High Risk Traits:

• Widely naturalized beyond native range
  
• Thrives in disturbed areas
  
• Congeneric weed (Digitalis lanata is noxious)
  
• Highly toxic to animals and humans
  
• Forms dense stands that displace native vegetation
  
• Self-compatible; reproduces without mates or pollinators
  
• Produces up to 500,000 seeds per plant
  
• Seeds viable in soil for at least five years
  
• Dispersed intentionally by people, as well as by wind and water
  
• Broad climate suitability (USDA zones 3–9)
  
• Tolerates wide range of soil types and pH levels

Low Risk Traits:

• Not an agricultural, forestry, or horticultural weed
  
• Lacks spines, thorns, or burrs
  
• Palatable to grazing animals (despite toxicity)
  
• Not allelopathic
  
• Requires soil disturbance to establish seedlings
  
• Reproduces only by seed; no vegetative spread
  
• Does not increase fire risk