page_title: Impatiens
section_title: Ecology
hierarchical_section_title: Impatiens / Ecology
caption_attribution_description: Deutsch: Indisches Springkraut am Erlenbach. English: Himalayan Balsam at the Erlenbach, tributary of the Nidda.
context_page_description: Impatiens is a genus of more than 1,000 species of flowering plants, widely distributed throughout the Northern Hemisphere and the tropics. Together with the genus Hydrocera, Impatiens make up the family Balsaminaceae.
  Common names in North America include impatiens, jewelweed, touch-me-not, snapweed and patience. As a rule-of-thumb, "jewelweed" is used exclusively for Nearctic species, and balsam is usually applied to tropical species. In the British Isles by far the most common names are impatiens and busy lizzie, especially for the many varieties, hybrids and cultivars involving Impatiens walleriana. “Busy lizzie” is also found in the American literature. The invasive alien Impatiens glandulifera is commonly called Policeman's helmet in the UK.
context_section_description: Most Impatiens species are perennial herbs. However, several annual species exist, especially in the temperate regions as well as in the Himalayas. A few Impatiens species in southeast Asia (e.g. Impatiens kerriae or Impatiens mirabilis) form shrubs or small trees up to three meters tall. Most Impatiens species occur in forests, especially along streams and paths or at the forest edge with a little bit of sunlight. Additionally, a few species occur in open landscapes, such as heathland, river banks or savanna.
  The genus Impatiens is characterized by a large variety of flower architectures. Traditionally two flower types are differentiated: one with a sacculate spur and a more or less two-lipped flower and a second with a filiform spur and a flat flower surface. However, several transition forms exist. Additionally, a group of 125 spur-less species exist on Madagascar, forming a third main flower type. Due to the large variability in flower architecture it seems reasonable to group the species by their main pollinators: such as bees and bumblebees, butterflies, moths, flies, and sunbirds. Further, a few cleistogamous species exist. However, most species are dependent on pollinator activity for efficient seed production but many of them are self-compatible. Most temperate species as well as some tropical species can switch from chasmogamous (pollinator-dependent) to cleistogamous (seed production within closed flowers) flowers when nutrient and light conditions become adverse.
  Impatiens foliage is used for food by the larvae of some Lepidoptera species, such as the dot moth (Melanchra persicariae), as well as other insects, such as the Japanese beetle (Popillia japonica). The leaves are toxic to many other animals, including the budgerigar (Melopsittacus undulatus), but the bird will readily eat the flowers. The flowers are also visited by bumblebees and certain Lepidoptera, such as the common spotted flat (Celaenorrhinus leucocera).
  Parasitic plants that use impatiens as hosts include the European dodder (Cuscuta europaea). A number of plant diseases affect this genus.
  The starkly differing flower shapes found in this genus, combined with the easy cultivation of many species, have served to make some balsam species model organisms in plant evolutionary developmental biology. Also, Impatiens is rather closely related to the carnivorous plant families Roridulaceae and Sarraceniaceae. Peculiar stalked glands found on balsam sepals secrete mucus and might be related to the structures from which the prey-catching and -digesting glands of these carnivorous plants evolved. Balsams are not known to be protocarnivorous plants, however.
  In 2011-2013, the United States experienced a significant outbreak of the fungal disease downy mildew that affects impatiens, particularly Impatiens walleriana.  The disease was also reported  in Canada as well.  The pathogen plasmopara obducens is the chief culprit suspected by scientists, but Bremiella sphaerosperma is related.  These pathogens were first reported in the United States in 2004.
caption: Himalayan balsam (I. glandulifera) invading habitat along a creek in Hesse
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