Carex divisa

Tracheophyta MagnoliopsidaCyperaceaeCarexCarex divisa

Ecology

A rhizomatous perennial herb of brackish ditches, dune-slacks and damp grasslands near the sea. It avoids areas of standing water. Lowland.

Status

Native

World Distribution

Submediterranean-Subatlantic element.

Broad Habitats

Neutral grassland (includes coarse Arrhenatherum grassland)

Light (Ellenberg): 8

Moisture (Ellenberg): 7

Reaction (Ellenberg): 7

Nitrogen (Ellenberg): 6

3

Salt Tolerance (Ellenberg): 3

January Mean Temperature (Celsius): 4.4

July Mean Temperature (Celsius): 16.4

Annual Precipitation (mm): 727

Life form information

Height (cm): 70

Perennation - primary

Perennial

Life Form - primary

Hemicryptophyte

Woodiness

Herbaceous

Clonality - primary

Rhizome shortly creeping

Count of 10km squares in Great Britain: 162

Count of 10km squares in Ireland: 4

Count of 10km squares in the Channel Isles: 1

Atlas Change Index: -0.35

Distribution information

JNCC Designations

NHMSYS0000456845

Scarce Atlas Account

Scarce Atlas Account: 

Carex divisa Hudson

Divided sedge

Status: scarce

 

A perennial sedge of grassland near the sea, C. divisa is moderately tolerant of salt, but absent from saltmarshes themselves. It is particularly characteristic of lightly grazed depressions in coastal pastures and the margin of grazing-marsh ditches on alluvial or sandy soils. It often accompanies Carex distans, Oenanthe lachenalii and Trifolium fragiferum in the damp brackish sward. C. divisa rarely occurs above 10 metres altitude, although it does occur on the inland margins of grazing marshes.

C. divisa has a far-creeping rhizome and much of its local spread is by vegetative means. Longer-distance dispersal by seed is frequent.

C. divisa is declining within most of its British range, and has disappeared from its inland sites. Many populations have been lost as a result of ploughing, drainage and industrial development of coastal grasslands (in particular the conversion of grazing marsh to arable land); increasing control of tidal water may also have contributed to its demise on some sites, by reducing the occurrence of brackish conditions inland.

C. divisa occurs inland in southern and south-central Europe, but is mainly coastal further north; it reaches its northern limit in Britain. It is also widespread in Mediterranean north Africa and west Asia.

 

J. O. Mountford

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 (367a)
Curtis TGF, FitzGerald RA
1994.  The re-discovery of Carex divisa Hudson, Divided Sedge, in Ireland. Irish Naturalists’ Journal. 24:496-498.
Curtis TGF, McGough HN
1988.  The Irish Red Data Book. 1. Vascular Plants.
Jermy AC, Chater AO, David RW
1982.  Sedges of the British Isles. Botanical Society of the British Isles Handbook no. 1, edn 2.
Stewart A, Pearman DA, Preston CD
1994.  Scarce plants in Britain.