Impatiens noli-tangere

Tracheophyta MagnoliopsidaBalsaminaceaeImpatiensImpatiens noli-tangere

Ecology

Our only native Impatiens is an annual plant of nutrient-rich soils in damp but not waterlogged woodland, occurring on streamsides and in valley-side seepages. Lowland.

Status

Native

World Distribution

Eurasian Temperate element; also in western N. America. The British sites for this species are amongst several scattered western outliers detached from its continuous range from C. Europe eastwards.

© K.J. Walker, BSBI

Broad Habitats

Broadleaved, mixed and yew woodland

Light (Ellenberg): 4

Moisture (Ellenberg): 7

Reaction (Ellenberg): 7

Nitrogen (Ellenberg): 6

0

Salt Tolerance (Ellenberg): 0

January Mean Temperature (Celsius): 2.6

July Mean Temperature (Celsius): 13.9

Annual Precipitation (mm): 1833

Life form information

Height (cm): 60

Perennation - primary

Annual

Life Form - primary

Therophyte (annual land plant)

Woodiness

Herbaceous

Clonality - primary

Little or no vegetative spread

Count of 10km squares in Great Britain: 21

Count of 10km squares in Ireland: 0

Count of 10km squares in the Channel Isles: 0

Atlas Change Index: -0.77

Distribution information

JNCC Designations

NBNSYS0000003186

Scarce Atlas Account

Scarce Atlas Account: 

Impatiens noli-tangere L.

Touch-me-not balsam

Status: scarce

 

 

This is essentially a woodland plant, occurring in damp, nutrient-rich soil in streamside silt and valleyside seepage areas. In the former it occurs chiefly under alder and oak and in the latter under oak and sometimes ash. Although an annual, it has few associated species and often forms pure stands. Most of the sites are below 100 metres but it reaches 200 metres at Dolgellau.

Flowering is from August onwards. Most flowers are produced in the more open, sunny and disturbed sites, as along woodland roads, around the bases of fallen trees and by car-parks. In shade, reproduction is most likely to be by cleistogamous flowers. The seeds probably have only a short viability and there is little evidence of a seed bank.

The populations are mostly small, 300-400 individuals, but some in the Lake District contain over 1000 plants. Although the Lake District populations fluctuate somewhat from year to year, they do not appear to be under any particular threat. However, populations on the Welsh borders have been reduced since 1950 by river management designed to increase flow rates.

This species is widespread throughout most of continental Europe, though absent from most of the Iberian peninsula, the extreme south-east and the extreme north. It ranges across Asia to Japan and in North America is largely confined to the north-west coast. 

I. noli-tangere is probably native only in the Lake District, where it is locally frequent, around Dolgellau and in a small area on the Montgomery-Shropshire border, where it was found, new to Britain, by G. Bowles in 1632. The numerous records from outside these `native' areas probably represent casual occurrences, originating perhaps as garden escapes or throw-outs, although it is rarely cultivated. Some may be the result of confusion with I. parviflora. Its claim to native status in the Lake District and Dolgellau is reinforced by the occurrence there of the only two British populations of the netted carpet moth Eustoma reticulatum, the larvae of which feed on I. noli-tangere (Hatcher & Alexander 1994), and by the presence of other oligophagous invertebrates (Coombe 1956).

 

 

P. E. Hatcher & G. Halliday

PLANTATT - Attributes of British and Irish plants. (.zip 1455KB) This dataset was compiled and published in 2004, and last updated in November 2008. Download includes an Excel spreadsheet of the attributes, and a PDF explaining the background and nomenclature. Note that the PDF version is the booklet as published, whereas the Excel spreadsheet incorporates subsequent corrections. A hardcopy can be purchased from the Centre for Ecology and Hydrology.

Atlas text references

Atlas (96a)
Hultén E, Fries M
1986.  Atlas of north European vascular plants north of the Tropic of Cancer. 3 vols.
Meusel H, Jäger E, Rauschert S, Weinert E
1978.  Vergleichende Chorologie der zentraleuropäischen Flora. Volume 2. 2 vols.
Stewart A, Pearman DA, Preston CD
1994.  Scarce plants in Britain.