Quiet, of course, it adheres to
The cracks of waste-pipes, velvets,
Velours them; an enriching
Unnatural ruff swathing the urban ‘manifestation’:
The urban nature is basemented, semi-dark:
It musts, it is alone.
John Silkin, Penguin Modern Poets 7
In the places that have most recently been abandoned to returning nature – such as disused car parks and the various hard standings from newly failed enterprise – we have found the first pioneering clumps of dark green moss. Somehow, these most ancient of botanical life-forms have found the most fragile of germinative footholds for their diminutive spores – often within the shallowest cracks created by fluctuations of heat or by settling of the ground.
It is thus the brave mosses that are the first to re-vivify the sterility of such terrain.
Favouring the dank (and low levels of light) these pioneering plants – known as bryophytes – began a very similar enterprise some 65,000,000 years ago; leaving the ancient seas to break ground across the barren land … and it was the dead, damp, mosses that made the first soils for the vascular plants that subsequently spread their living carpets across the earth.
Mosses are small, soft plants that are typically 1–10 cm (0.4–4 in) tall, though some species are much larger. They commonly grow close together in clumps or mats in damp or shady locations. They do not have flowers or seeds, and their simple leaves cover the thin wiry stems. At certain times mosses produce spore capsules which may appear as beak-like capsules borne aloft on thin stalks.
Botanically, mosses are bryophytes, or non-vascular plants. They differ from ‘higher’ plants by not having internal water-bearing vessels or veins, and no flowers and therefore no fruits, cones or seeds. They are small (a few centimeters tall) and herbaceous (nonwoody) and absorb water and nutrients through their leaves. Mosses have stems which may be simple or branched and upright or lax, simple leaves that often have midribs, roots (rhizoids) that anchor them to their substrate, and spore-bearing capsules on long stems. They harvest sunlight to create food through photosynthesis. Mosses do not absorb water or nutrients from their substrate through their roots, so while mosses often grow on trees, they are never parasitic on the tree.
They can be distinguished from the similar liverworts by their multi-cellular rhizoids. Also, in most mosses, the spore-bearing capsule enlarges and matures after its stalk elongates, while in liverworts the capsule enlarges and matures before its stalk elongates. Other differences are not universal for all mosses and all liverworts, but the presence of a clearly differentiated stem with simple-shaped, ribbed leaves – without deeply lobed or segmented leaves and not arranged in three ranks – all point to the plant being a moss.
There are approximately 12,000 species of moss classified in the Bryophyta.
Moss is often considered a weed in grass lawns, but is deliberately encouraged to grow under aesthetic principles exemplified by Japanese gardening. Moss is thought to add a sense of calm, age, and stillness to a garden scene.
A passing fad for moss-collecting in the late 19th century led to the establishment of mosseries in many British and American gardens. The mossery was typically constructed out of slatted wood, with a flat roof, open to the north side (maintaining shade). Samples of moss were installed in the cracks between wood slats. The whole mossery would then be regularly moistened to maintain growth.