Sphagnum balticum C. E. O. Jensen 1890

Recent studies of this moss suggest that it might be what is called a 'colonist' species. This means it is amongst the first species to colonise a new site. However, it does not appear to be a competitive species, so when other mosses and higher plants move on to the site, Baltic bog moss disappears.

Baltic bog moss is listed in the UK Biodiversity Action Plans (UK BAP), and is included in English Nature's Species Recovery Programme (SRP). The most important tasks behind protecting this moss are as follows: to re-survey those sites where it is known to have occurred in the past; ensure the survival of the moss where it is still found; establish ex-situ colonies (from British plants) to provide specimens for re-colonising suitable sites. It is also important that the precise habitat requirements of this species are known, particularly in view of its intolerance of poor water quality. It is hoped that more bryologists will be trained to identify this species and encouraged to report any new records. Finally, the indiscriminate collecting of sphagnum from the wild for use by the horticulture industry (for use in hanging baskets and displays) should be discouraged, perhaps by using local publicity and information boards at the appropriate sites.

This rare moss can grow whilst completely or partly submerged in water. It resembles several other members of the sphagnum moss family and ranges from dull green to orange in colour. It can form large floating mats under the right conditions but, typically, occurs as scattered shoots amongst other bog mosses.

Baltic bog moss, as its name suggests, is found in raised bogs holding water containing few nutrients. Occasionally, it is also found in blanket bogs.

It has been recorded from seven different and widely scattered sites in the UK, and it seems it has disappeared from four of these. In England there are three recorded sites, in Cheshire (from where it has not been seen for over a century), Yorkshire (not seen in recent years) and Northumberland, which is the only current site in England. The only known Welsh site is in Ceredigion (Cardiganshire), and it has not been seen here since 1967. In Scotland, it is recorded in Aberdeenshire, Dumfriesshire and Abernethy Forest in Inverness-shire but, here too, it has disappeared from two sites. Outside of the UK, it has an extensive range across the lowlands of the northern hemisphere, although it is confined to the more northerly latitudes.

Classified as Endangered in the UK, and protected by Schedule 8 of the Wildlife and Countryside Act, 1981.

One of the reasons for the disappearance of this moss from two of the Scottish sites is due to the afforestation of much of these upland bogs. This dates from the time when upland mires and bogs were not considered to be sites worthy of protecting. As well as shading, the moss is affected by changes in the water quality, particularly increased acidity and higher nutrient levels. Drainage of bogs and peat-cutting are also potential threats to this species, along with inappropriate gathering of all sphagnum species by the horticultural trade and by local collectors.

Unlike Sphagnum angustifolium and S. annulatum, S. balticum has stem leaves exerted at right angles to the stem. It also has fewer and weaker hanging branches than does S. angustifolium, which make the stem itself often visible and the stem leaves easier to see. Sphagnum balticum also lacks the paired pendent branch buds between the capitulum rays as seen in S. angustifolium.

In Sphagnum kenaiense there are sometimes spreading stem leaves but this species has 2 hanging branches per fascicle.

Plants small to moderate-sized, soft and ± weak-stemmed; brownish green, yellow-green, yellowish to golden brown, capitulum typically flat and 5-radiate. Stems pale green to brown, branch bases sometimes reddish; superficial cortex of 2-3 layers of moderately thin-walled and differentiated cells. Stem leaves 0.8-1.1 mm, triangular-lingulate to lingulate, concave, spreading, apex broadly obtuse, hyaline cells fibrillose in apical region. Branches slender and tapering, often 5-ranked and decurved, leaves somewhat elongated at distal end. Branch fascicles with 2 spreading and mostly 1 pendent branch. Branch stem green, cortex enlarged with conspicuous retort cells. Branch leaves ovate-lanceolate, 1-1.7 mm, straight, slightly undulate and spreading; margin entire, hyaline cells on convex surface with 1-5 pores in cell ends and free near apex, on concave surface with round wall thinnings in cell ends and angles; chlorophyllous cells triangular in transverse section and well-enclosed on concave surface. Sexual condition dioicous. Spores 25-33 µm; smooth to finely papillose on both surfaces; proximal laesura approximately 0.5 spore radius.

Sphagnum recurvum subsp. balticum Russow, Sitzungber. Naturf.-Ges. Univ. Dorpat 9: 99. 1890

Sphagnum balticum Russow ; C. Jens. Fests. Bot For. Kjob. 100. 1890.
Sphagnum recurvum balticum Russow, Sitz.-ber. Nat.-Ges. Dorpat 9: 111. 1890.
Plants rather small and delicate, generally yellowish or strongly tinged with brown. Wood-cylinder yellow-green ; cortical cells of the stem differentiated, in 2-3 layers, irregular in size and shape with relatively thick walls, the outer cells quadrilateral, generally longer than wide, without fibrils or pores: stem-leaves rather small, triangular-Ungulate to oval, as wide as or wider than long, obtuse at the apex and very slightly lacerate, the border broad, very broad toward the base, the walls of its cells pitted; hyaline cells narrow, shorter in the apical part, not divided, with fibrils or stumps of fibrils in the cells of the apical part, the membrane resorbed on the inner surface in the cells of the apical part and downward in the center of the leaf, on the outer surface with small pores near the commissures in the apical cells: branches in fascicles of 3 or 4, 2 spreading, their cortical cells in a single layer, the retortcells of good size with fairly conspicuous necks, sometimes a second cell above the first: branchleaves hardly or slightly undulate, ovate-lanceolate, sometimes slightly subsecund, abruptly contracted to the involute toothed apex, the border entire, of 2-3 rows of narrow cells; hyaline cells fibrillose, narrowly rhomboidal, 10-14 times as long as wide at the base, shorter above to 6-8 times, on the inner surface with pores in the ends and corners of the cells, 3 or 4 per cell, on the outer surface with similar ringed pores and also smaller pores along the commissures, up to 7-8 per cell: chlorophyl-cells in section triangular with the base exposed on the outer surface, the apex of the triangle rarely reaching the inner surface of the leaf, the lumen triangular-ovate; hyaline cells slightly convex on the inner surface, one sixth to one fifth of the diameter of the cell.
Dioicous.
Type i/icamty: Livonia. Russia.
I>istkibi;tion: Greenland; Alaska; also in northern Ivuropc and reported from Asia.