Foxglove

Scientific name: Digitalis purpurea
  • Key characteristics
  • Biology
  • Impacts
  • Control
  • Further information

  • Erect, rosette-based biennial or short-lived perennial
  • In its second year, each plant produces a single flower stalk, up to 2 m tall
  • Attractive pinkish purple or white flowers are arranged on a long, one-sided, tapering spike. Each flower is a nodding, tubular ‘bell’ up to 5 cm long, with dark purplish spots inside
  • Rosette leaves are green, downy, finely wrinkled on the upper surface, grey and woolly underneath. Leaves are oval or lance-shaped, up to 25 cm long by 12 cm across, with bluntly-toothed margins. Rosette leaves have stalks but leaves on the flowering stem are stalkless or almost so.

Origin and habitat

  • Native to western Europe, south to Spain and east as far as Czechoslovakia, now widely distributed throughout New Zealand but less common in drier areas
  • Common in poorer pastures, second-growth bush, disturbed ground, waste places and lime-free soils
  • Considered a very serious problem in parts of New Zealand in the late 1800s  and was included as a noxious weed in the Second Schedule of the Noxious Weeds Act of 1900 by special Gazette Notice of 21st December 1905
  • Always common on pastures newly cleared from bush but rarely persists as pastures thicken and are improved.

Life-cycle

  • The seeds are dust-like, about 0.8 mm long, and can be spread by strong winds
  • In its first year the rosette of dark-green to white-woolly leaves is formed. In the plant’s second year of growth the flower stem grows from the rosette
  • In most cases the plant dies after its seed has been shed, but under favourable conditions plants can sometimes survive for another year or two after flowering.

Benefits

  • Traditionally used in herbal remedies but today is a source of drugs used as heart stimulants
  • Has been grown overseas as a crop for extraction of the heart drug digitalin
  • Both this species and the related species Digitalis lutea have attractive flowers and are sometimes cultivated as garden plants.

  • All parts of the plant are very poisonous to humans and livestock but are not usually touched by grazing animals; the seeds are especially toxic to humans
  • Listed among the National Poisons Centre’s top ten poisonous plants; consistently involved in unintentional childhood poisonings.

Impact on pasture

  • Dense infestations of foxgloves, sometimes seen in new pastures sown following bush clearance, take up space that would be better occupied by desirable pasture species.

Impact on livestock

  • Fortunately foxglove foliage is quite unpalatable to livestock, so the main effect from infestations is a reduction in pasture productivity due to the replacement of more valuable forage species.

Grazing management

  • Patience is probably the best weapon against a foxglove infestation
  • Often foxgloves are most prevalent in new pasture freshly cleared from bush
  • As pasture strengthens and thickens, new foxglove seedlings find it harder to establish successfully
  • Sowing of pasture species appropriate to the local environment, using suitable fertilisers and careful use of grazing management to strengthen the new pastures will all help to hasten the decline of foxgloves.

Chemical control

  • Foxgloves are difficult to control chemically and economic chemical control is difficult to achieve
  • A combination of aminopyralid and triclopyr will control foxglove, but is also damaging to clovers, therefore, it is better used as a spot treatment.

  • Popay I, Champion P, James T 2010. An illustrated guide to common weeds of New Zealand. New Zealand Plant Protection Society, Christchurch, New Zealand. 416 p.