Hammarbya paludosa

Tracheophyta MagnoliopsidaOrchidaceaeHammarbyaHammarbya paludosa


A pseudobulbous herb of boggy areas where the water is usually acidic but subject to some lateral movement. Typically it grows amongst saturated Sphagnum, but also on peaty mud and among grasses on the edges of runnels and flushes. 0-500 m (Llyn Anafon, Caerns.).



World Distribution

Circumpolar Boreal-montane element, with a disjunct distribution.

© K.J. Walker, BSBI

Broad Habitats

Fen, marsh and swamp (not wooded)

Light (Ellenberg): 9

Moisture (Ellenberg): 9

Reaction (Ellenberg): 2

Nitrogen (Ellenberg): 1

Salt Tolerance (Ellenberg): 0

January Mean Temperature (Celsius): 2.9

July Mean Temperature (Celsius): 13.3

Annual Precipitation (mm): 1615

Height (cm): 8

Perennation - primary


Life Form - primary




Clonality - primary

Little or no vegetative spread

Clonality - secondary

Detaching ramets on leaves (Hammarbya)

Count of 10km squares in Great Britain: 302

Count of 10km squares in Ireland: 44

Count of 10km squares in the Channel Isles: 0

Atlas Change Index: -0.32

JNCC Designations


Scarce Atlas Account

Scarce Atlas Account: 

Hammarbya paludosa (L.) Kuntze

Bog orchid

Status: scarce



H. paludosa is found in boggy areas where the drainage water is moderately acidic. It frequently grows in sphagnum and can also be found on peaty mud and among grasses on the edges of runnels. In most sites it is associated with some water movement. Associated species are numerous but often include Carex echinata, Drosera rotundifolia, Erica tetralix, Molinia caerulea, Nardus stricta and Rhynchospora alba. In some sites Vaccinium oxycoccos is quite frequent. In Merioneth, and perhaps elsewhere, it tends to occur where bogs are flushed with water from base-rich rocks, growing with base-demanding sphagna such as S. contortum, S. teres and S. warnstorfii. H. paludosa is generally a lowland species, though it has been recorded up to 500 metres on Millfore and at Llyn Anafon.

H. paludosa is a perennial with a long flowering season: there may be plants in flower in one colony from the end of June until the second half of September. Though seed is often set, this species also reproduces vegetatively by means of bulbils which develop on the leaf tips and which, having become detached, develop into new plants (Summerhayes, 1951).

The drainage of bogs has brought about a dramatic decrease in the number of recorded sites, especially in lowland England. In lowland mires systems such as the New Forest the species depends on grazing to maintain open runnels, flushes and Molina-free mires in which it grows. The tiny, shallow-rooted plants are vulnerable to nearby trampling which can cause them to pop out of the ground. However, there are many areas in Scotland where H. paludosa could well be thriving unseen. More sites arc known in Cumbria, for example, than at any time in the past simply as a result of recent intensive recording.

H. paludosa is most frequent in northern and central Europe, but it is also recorded at scattered localities in the boreal zone of Asia and North America. It is considered to be under threat in Europe as a whole. 

Because of its small stature (sometimes under 3 cm in height), sporadic appearance and pale coloration, H. paludosa is notoriously difficult to find and may often escape detection. It could well be holding its own in the more western and northern parts of Great Britain.



M. S. Porter

Atlas text references

Atlas (335c)
Allan & Wood (1993)
Curtis TGF, McGough HN
1988.  The Irish Red Data Book. 1. Vascular Plants.
Hultén E, Fries M
1986.  Atlas of north European vascular plants north of the Tropic of Cancer. 3 vols.
Meusel H, Jäger E, Weinert E
1965.  Vergleichende Chorologie der zentraleuropäischen Flora. Volume 1. 2 vols.
Stewart A, Pearman DA, Preston CD
1994.  Scarce plants in Britain.