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Irish Marsh-orchid
Dactylorhiza occidentalis

This Irish endemic is very tricky to identify, especially where it grows in close proximity to Narrow-leaved Marsh-orchid Dactylorhiza traunsteinerioides, Northern Marsh-orchid Dactylorhiza purpurella, and Early Marsh-orchid Dactylorhiza incarnata. Dactylorhiza occidentalis is locally common in parts of Ireland and Northern Ireland, where it flowers early (from mid May to mid June); this helps avoid confusion with one of the similar species, Northern Marsh-orchid. The Irish Marsh-orchid does, however, flower at the same time as Early Marsh-orchid, but the latter has smaller flowers and narrower leaves. Dactylorhiza occidentalis favours alkaline habitats including lough margins, roadside verges, marshy meadows and dune slacks.

Distribution Map Key Features
distribution map

Records for the Irish Marsh-orchid from BSBI are shown on the map with most recent in front. (Hover the mouse over the small map to expand it.)

CLICK HERE to visit the BSBI website page for updated data and maps with separated data for individual record periods.

Plant: 10 to 40cm tall, occasionally to 50cm; stem green but flushed purple towards the tip, where it is also ridged; somewhat hollow.
Leaves: up to 5 sheathing leaves arranged at the base of the stem and 2 to 3 non-sheathing leaves higher up; green, with a significant number of plants displaying brown spots, rings or dashes that tend to be concentrated from the middle to the tip of the leaf. There are sometimes markings on the lower surface of the leaf.
Bracts: long; green and washed purple.
Flowers: up to 20 on a densely packed inflorescence; quite large; mainly purple or dark pink. The upper sepal and petals form a hood that encloses the column; the lateral sepals are close to horizontal. The lip is usually wider than it is long and is divided into 3 rounded lobes, often with wavy margins. The lip is pink, becoming paler or white towards the base, and has numerous darker dots and dashes both within and outside rings or loops.

Image Gallery for Irish Marsh-orchid Dactylorhiza occidentalis


Pollination Taxonomy & Hybrids

Very little is known about the reproduction of the Irish Marsh-orchid.

The specific name 'occidentalis' means 'western'.

Subspecies: none.
Varieties: Dactylorhiza occidentalis var. kerryensis always has unspotted leaves and is reported to be a shorter plant with smaller, paler flowers; it may be closely allied to the Southern Marsh-orchid Dactylorhiza praetermissa.
Hybrids: Dactylorhiza x dinglensis is a hybrid with Heath Spotted-orchid Dactylorhiza maculata. Dactylorhiza x aschersoniana is a hybrid with Early Marsh-orchid Dactylorhiza incarnata. Dactylorhiza x braunii is a hybrid with Common Spotted-orchid Dactylorhiza fuchsii and is reported from County Clare.

Articles about Irish Marsh-orchid in JHOS