Car-pet Moss

Silvery Bryum (Bryum argenteum)

For evidence of how little we use the car – and how infrequently we wash it – you need look no further than the window "sill" on the passenger side. Sheltered from the summer sun by a thick Leyland Cypress hedge (and from the winter sun by the bulk of the house), it provides a perfect substrate for a diminutive carpet of Silvery Bryum (Bryum argenteum). Mike got these closeup portraits of the spiky little moss with its distinctively silvery tipped lobes. This widespread species is said to be one of the most recognisable of Britain's mosses, and is one of the most common in urban areas. It forms compact patches less than 1 cm (about a half-inch) high, typically appearing quite "shiny" and always showing those silvery tips. Tolerant of high-nutrient substrates, it cohabitates well with humans, regularly growing in places such as pavement cracks, railway lines, stone walls, roofs, tarmac, arable fields and path edges. In the "wild", it also grows on regularly disturbed ground, such as sand dunes and eroding river banks or cliffs. It's found around the world, from the cities of Europe and North America to the vast deserts of Australia and the frigid plains of Antarctica – quite a hardy and adaptable little plant!

Against the wall

Wall Screw-Moss (Tortula muralis)

While most of the garden goes into some level of hibernation for the winter, mosses are an exception. Right now, many of them are in their prime – lush and green and studded with numerous spore capsules. Our windowsills, roof tiles, and the top of the stone wall between ours and a neighbouring property are currently bristling with the lance-straight sporophytes of Wall Screw-Moss (Tortula muralis). This is one of the commonest mosses on brick and stone in Britain, and one of the first that neophytes like us learn to identify. Like the Grey-cushioned Grimmia (Grimmia pulvinata), this one has a long hair (called a "nerve") that extends from the tip of each leaf, as seen in the picture below. (Click on the picture to see it at a larger size.) Its leaves, when wet, like now, are bright green and opaque, developing into little cushions about a centimetre high. When it's dry, as in the summer, those nerves make the moss look frosty grey. Currently, the spore capsules end in spiky caps, but once the spores have finished developing, those caps will drop off. Then, a network of twisted hairs known as the peristome (the partial remnants of dead cells) which surround the mouth of the spore capsule will help to ensure that the spores are dispersed gradually rather than all at once. Given the vast number of little colonies sprinkled throughout the garden, this must be a pretty successful strategy.

Showing the twisted peristomes

Windowsill hedgehogs

Grey-cushioned Grimmia (Grimmia pulvinata) 

As the days get steadily longer (and occasionally warmer) the garden is stirring back to life. Among the brightest greens in view at the moment are the humped little mounds of an impressive variety of mosses, most as yet unidentified. The roof tiles and windowsills of our house and its various outbuildings are covered with them! We've managed to work out the ID of a few, like this Grey-cushioned Grimmia (Grimmia pulvinata), which is named for the carpet of long, dense hairs that extend from the tips of its leaves. These also give the moss its other common name – Hedgehog Grimmia. This is one of the easiest mosses to put a name to, at least when it has young spore capsules like the one above does. These green capsules curl back into the cushion on arching stems, only standing upright when they become old, dry and brown. Each capsule has a long, pointed "beak" at the tip, which helps to distinguish them from the superficially similar Grimmia orbicularis with its rounded tip. Its elliptically-shaped leaves are distinctive. It's a widespread moss, found across much of the UK, primarily in the lowlands. Elsewhere, it occurs across most of the globe, and is the most common species in its genus. It prefers sunny locations, and usually grows on stone rather than trees and shrubs. In the wild, it occurs on limestone or calcareous cliffs and boulders. However, because it can tolerate moderate levels of pollution, it's also common in urban and suburban areas, where it grows on mortar, tombstones, asbestos and concrete. So it's not an unexpected resident in our garden, but a welcome splash of greenery none-the-less.

Starry

Springy Turf-moss (Rhytidiadelphus squarrosus)

Now that winter is well and truly on its way, things are slowing down considerably in the garden. But some things are now coming into their own — including the mosses, which are really enjoying our recent rains. One of the garden's most common species is Springy Turf-moss (Rhytidiadelphus squarrosus), which has spread throughout most of the lawn, particularly where the grass is short. The moss's long stems (sometimes as long as 15-20 cm; 4-6 inches), yellow-green colour and sharply splayed leaves are distinctive. From above, it has quite a "star-like" appearance. It has red stems too, but these are often almost completely hidden by the broad leaves (broad for a moss, anyway). It thrives in unimproved and semi-improved grasslands, and is ubiquitous across the UK. It's widespread in Eurasia and North America (where it's known as Square Goose Neck Moss) too, and has been accidentally introduced into parts of the southern hemisphere. Speaking from experience, I can tell you that it makes a wonderfully soft cushion for those of us who spend time sprawled out flat on the lawn!