Puzzling Hoary Mosses: Grimmia, Schistidium and Racomitrium
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Sphagnum fuscum and S. beothuk in Britain and Ireland Beginners Corner 112: extensive sloping mire, 100 m alt., NW of 110: hummock at edge of bog pool in blanket Loch Basta, Yell, HU504952, 2000, Payne (E); mire, 111 m alt., Loch nan Steàrnag, Pentland H18: raised bog, 90 m alt., Raheenmore Bog, Road, Lewis, NB324366, 2016, ap Rheinallt; Puzzling hoary N43, 2014, Moen, det. Flatberg (TRH); H22: H02: bog, Cores bog, W side of Mangerton Rossan Bog, half mile SE of Kinnegad, N54, Mountain, V98, 1983, Synnott (BBSUK); 1956, King (BBSUK). H09: hummock on bog, near Kilkishen, R5175, mosses: Grimmia, Sphagnum beothuk. 9: hummocks in valley 1979, Lockhart; H10: bog, Carrig, SW of Birr, mire, 25 m alt., Lower Hyde Bog, nr Bere N00, 1965, King (BBSUK); H14: hummocks Regis, SY872922, 2006, Edwards (BBSUK); in raised bog, 110 m alt., Caher Bog, S2691, Schistidium and 46: raised mire, Cors Fochno, SN6391, 1987, 2009, Hodgetts (BBSUK); H15: raised bog, nr Blackstock; 48: hummocks in acid bogland, 200 Woodford, M70, 1962, Smith (BBSUK); H16: m alt., near Trawsfynydd, SH63, 1978, Benoit robust hummock in degraded bog, 13 m alt., Racomitrium Racomitrium aciculare bearing its distinctive, erect capsules (BBSUK); 66: Widdybank Fell, NY818290, Pollagh, Moycullen, M201377, 2016, Eakin; 2007, O’Reilly; 69: Witherslack, SD4284, H17: large raised bog, Addergoole North, River In September 2016 an excellent Grimmia identification workshop was delivered 1884, C.H. Waddell (E); 70: raised bog, 10 m Suck, near Ballinasloe, M83, 1968, Birks (E); by Ron Porley on behalf of the BBS. Some participants noted how difficult it alt., Glasson Moss, NY2360, 1959, Paton (E); H18: raised bog, 60 m alt., Woodfield Bog, can be to distinguish some Grimmia species without capsules from members of 73: bog, 250 m alt., Corranoch Bog, the Silver near Clara, N23, 1990, Long (E); H19: bog, Flowe, NX473830, 1966, Birks (E); 74: 10 m Mouds Bog, near Newbridge, N81, 1956, King the closely related genera of Schistidium and Racomitrium, producing the first alt., Borrow Moss, Wigtown, NX4357, 1977, (BBSUK); H23: Derries Bog, N04, 1952, King kernels of an idea for this Beginner’s Corner. Sharon Pilkington Corner; 87: raised bog, Flanders Moss, NS69, (BBSUK); H24: Cloontirm Bog, nr Longford, 1979, Chamberlain (E); 88: wet base-rich N17, 1966, King (BBSUK); H25: hummocks epending on where you do your Common species like Grimmia pulvinata, flushes, 195 m alt., near Milton of Invervack, on raised bog, 53 m alt., Derreenasoo Bog, bryologising, you’re almost G. donniana, Schistidium crassipilum and Blair Atholl, NN8364, 1981, Chamberlain & G9309, 2016, Eakin & Fernandez, det. Lockhart; certainly familiar with some of the Racomitrium aciculare are usually so distinctive Long (E); 89: raised bog, 380 m alt., Dun Moss, H27: tussock on blanket bog, near Lough DGrimmiaceae. In the British Isles this large that it quickly becomes second nature to NO15, 1967, Brookes (E); 97: open raised bog, Namucka, Louisburgh, L8275, 1951, Dalby family currently includes 28 species in Grimmia1, recognise these when they are growing well and 130 m alt., W of Leanachan, Leanachan Forest, (BBSUK); H28: ombrotrophic blanket bog, 19 in Schistidium, 13 in Racomitrium and 1 in in typical habitats. With others, when the plants NN1978, 1986, Long (E); 98: 298 m alt., by 152 m alt., Fiddandarry Bog, Ox Mountains, Coscinodon. Most of these are small, cushion- or bear capsules the differences between the genera A82 N of Lochan na h-Achlaise, NN3148, 2011, G392224, 2016, Douglas & Lockhart, conf. tuft-forming mosses which grow in sunny places are usually obvious. Kyrkjeeide & Kyrkjeeide, det. M.O. Kyrkjeeide Flatberg; H29: hummock on raised bog, South on hard rock. However, vegetative differences are often much (TRH); 102: Islay, Duich Moss, NR3355, 1998, Cashel, N085900, 1986, Douglas & Grogan Although the species of the Grimmiaceae are more subtle. Sooner or later you are likely to O’Leary; 104: valley mire, 50 m alt., Portree, (BBSUK); H30: hummocks on raised bog, 55 very variable, the combination of leaves with encounter puzzling plants without capsules and above Sluggans, NG460452, 2016, Hodgetts; m alt., Drummany Bog, H4017, 2016, Eakin (i) usually some cells with slightly to strongly then it can be difficult to know if you have found 105: hummocks on raised bog, 15 m alt., near & Fernandez, det. Lockhart; H32: Scottstown, sinuose walls and (ii) a whitish hair-point (when a Grimmia, a Schistidium or a Racomitrium (or Loch Sguod, NW of Poolewe, NG812879, Red Bogs, H63, 1900, C.H. Waddell (CGE); present) arising directly from the leaf tissue, even a completely unrelated species such as 1986, Long (E); 107: blanket bog, 225 m alt., H33: undisturbed blanket bog, Pettigoe Plateau, rather than extending from the nerve will serve Dicranoweisia cirrata or Didymodon rigidulus). In by Loch Gaineamhach, Lairg to Tongue road, H035644, 2011, Forster Brown (NMW); H34: to separate members of the Grimmiaceae from fact many of our Grimmia species rarely or never NC513259, 2006, Chamberlain & Kungu (E); large hummock in blanket bog, 150 m alt., other acrocarps in different families. produce capsules. 108: blanket bog, 190 m alt., W of Lochan nan Croaghonagh Bog, H053885, 2008, Hodgetts The following tables provide you with some Clach Geala, NC926494, 2015, Charman; 109: (BBSUK); H36: hummocks in raised bog, 70 1 Following Ron Porley’s conspectus of broad guidance in distinguishing Grimmia, blanket bog, 100 m alt., Shielton Peatlands, m alt., Tully, NW of Omagh, H417758, 2016, Grimmia which currently includes G. ramondii Schistidium and Racomitrium. Do bear in Flow Country, ND195477, 2002, Porley; Long. (Dryptodon patens) but not Coscinodon cribrosus mind though that many species are highly 3030 FieldFieldBryologyBryology No117No117 || May17May17 FieldBryology No117 | May17 31 Beginners Corner Beginners Corner Table 1. Growth form and substrate Table 2. Vegetative characters Grimmia Schistidium Racomitrium Grimmia Schistidium Racomitrium Growth form Various cushion-, tuft- and Mostly tuft-formers. Mostly patch-formers but some Colour patch-formers Sometimes cushion-forming tuft- and cushion-formers Various shades of green (beware G. Some species have reddish/ Various shades of green e.g. young S. crassipilum elongata) yellowish pigments Often have numerous short Nerve in TS Cells differentiated. At the base of the Cells little differentiated Cells little differentiated stubby-looking branches leaf a row of at least 4 guide is present (except in S. maritimum) Substrate Hard rocks and masonry. Hard rocks and masonry Hard, mainly acid rocks, also on the ventral side, with a row of Most species prefer acid rocks some ground-dwellers stereids and sometimes hydroids below although some are calcicoles Hair-point Present or not Present or not. If present often Present or not. If present short and may be toothed often toothed variable and leaf cell characters in particular in the uplands) but others are calcicoles and Terete at the point of insertion on the can be very complex, leading to difficulties usually grow on natural limestone, concrete, wall leaf tip Terete at the point of insertion Flattened at the point of in separating Grimmia and Schistidium in mortar or other man-made calcareous substrates. on the leaf tip insertion on the leaf tip particular. A few such as Racomitrium ericoides typically Upper leaf Entire Toothed (S. apocarpum and S. Usually entire (toothed in R. grow directly on the ground whilst Schistidium margins crassipilum) or entire aciculare) Growth form and substrate (Table 1) rivulare, R. aciculare and others specialise in rock, Cell walls at Usually straight-sided to slightly Usually slightly sinuose, Strongly sinuose At first, many of the Grimmiaceae can look tree roots and other substrates associated with base of leaf sinuose or nodulose sometimes straight-sided superficially similar, forming dense cushions on running water. rock, or looser tufts and patches. Most species base (depending on the species), although they are strongly associated with hard, igneous or Vegetative characters (Table 2) may be more strongly sinuose elsewhere in the metamorphic acid rock such as granite (often In the field, a useful distinguishing character that leaf. with practice can be observed with a hand-lens You’ll need a high-power microscope and is the nature of the leaf hair-point. Species of a steady hand to examine the leaves. When Racomitrium have hair-points that are flattened selecting leaves to place on your slide, make sure at the point of insertion on the leaf tip whereas you choose mature ones from the upper part those of Grimmia and Schistidium are terete of a well-grown shoot. If you are examining a (round). However not all species have hair- cushion-former, select leaves from young shoots points and in others they may be very short and within the cushion. inconspicuous. Separating vegetative Grimmia from Under the microscope, species of Racomitrium Schistidium can be tricky and here it is often are usually relatively straightforward to separate helpful to examine a nerve in transverse section from Grimmia and Schistidium. Examination (TS). Grimmia has a ventral row of guide cells, of the cells at the base of the leaf will show that usually 4 in the leaf base, a row of stereids and in Racomitrium they are clearly elongate and sometimes hydroids. Schistidium lacks this strongly sinuose down to the extreme leaf base. specialisation of cells so in TS the nerve looks In Grimmia and Schistidium they usually have rather homogenous and lacks stereids. Beware of straight-sided or slightly sinuose walls in the leaf poorly developed plants! v Top. Grimmia laevigata is an uncommon cushion- wTop. Grimmia dissimulata nerve section showing cell former that rarely has capsules. differentiation. v Bottom. Schistidium elegantulum: a strikingly hoary wBottom. Racomitrium aciculare has elongate basal leaf cells cushion-former. This plant has very few capsules with strongly sinuose walls. 32 FieldBryology No117 | May17 FieldBryology No117No117 || May17May17 3333 Beginners Corner Beginners Corner Table 3.