Bryum marratii - BBS Field Guide

582<br />

Bryales<br />

Nerve ends<br />

below blunt<br />

leaf tip<br />

1 mm<br />

Identification<br />

Similar species<br />

<strong>Bryum</strong> <strong>marratii</strong><br />

Baltic <strong>Bryum</strong><br />

1 mm<br />

2 mm<br />

B. <strong>marratii</strong> 1 mm<br />

Photos David Holyoak Drawing Jonathan Graham Text Mark Lawley<br />

Beaked lid<br />

B. <strong>marratii</strong><br />

B. <strong>marratii</strong><br />

This is one of several very uncommon <strong>Bryum</strong> species with blunt-tipped leaves. Its<br />

shoots form rather bright green patches 2–10 mm tall. Leaves are very concave,<br />

blunt-tipped, oval-oblong, about 0.75–2 mm long and up to 2.5 times longer than<br />

wide. Capsules are uncommon, maturing in autumn. They are only about 1.5 mm<br />

long, and no more than 1.5 times longer than wide, with a beaked lid.<br />

B. <strong>marratii</strong> occurs mainly at the upper edge of saltmarshes, whereas the even<br />

rarer B. calophyllum (Smith, p. 540; also see photographs on opposite page) prefers<br />

base-rich coastal sands, particularly in dune slacks. Small plants can be difficult<br />

to distinguish, but the leaves of B. calophyllum are more strongly bordered and<br />

somewhat shorter relative to their length (about twice as long as wide), often with<br />

a tan to pinkish colour. The best distinction between these two species is that the<br />

capsules of B. calophyllum (which mature in autumn and winter) are about twice<br />

as long as wide, with a bluntly conical lid.<br />

Another rare species, B. cyclophyllum (Smith, p. 547) also has wide, bluntly tipped<br />

leaves that are somewhat concave; it is a much softer plant than the common<br />

Rhizomnium punctatum (p. 616), with a less well-defined leaf border. Filamentous<br />

gemmae sometimes occur in the leaf axils, but capsules are unknown in Britain.<br />

It grows on moist, bare soil, especially in the inundation zones of large lakes and<br />

reservoirs.

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3 mm<br />

2 mm<br />

B. neodamense 5 mm<br />

Bluntly<br />

conical lid<br />

Bryales<br />

Bryales<br />

B. calophyllum<br />

B. calophyllum<br />

The rare B. muehlenbeckii (Smith, p. 586) appears to consist of unusual forms<br />

of B. alpinum (p. 599) that have grown partly or entirely submerged. It has bluntly<br />

tipped, concave leaves, and forms green, or red-tinged tufts or patches 2–7 cm tall<br />

on acidic rocks in and near water courses in the mountains. The lower part of the<br />

stems is covered by long rhizoids which may bear orange-red tubers identical to<br />

those of ordinary B. alpinum. Capsules are not known in Britain.<br />

Rare forms of B. pseudotriquetrum (called B. neodamense in Smith, p. 566; also see<br />

photograph above) occurring in base-rich sites that are prone to flooding, have leaves<br />

which are concave, bluntly tipped and do not run down onto the stem, but resemble<br />

those of ordinary B. pseudotriquetrum (p. 592) in being rather evenly spaced along<br />

the stem and are distinctly bordered.<br />

Habitat<br />

B. <strong>marratii</strong> grows mainly at the upper edge of saltmarshes, and rarely on dune slacks.<br />

583