Drive through the American Deep South and you pass beneath it for miles: long silver-grey beards hanging from the live oaks, stirring in air that hardly moves. Spanish moss looks every inch the part, soft and grey and draping, and yet it is no moss. It is a flowering plant, and a fairly close relative of the pineapple.
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A cousin of the pineapple
Spanish moss is Tillandsia usneoides, one of the air plants, and it belongs in the bromeliad family with the pineapple and the spiky tank bromeliads sold as houseplants. A close look tells it apart from a true moss straight away. It carries a real, if wiry, stem that branches and trails in long festoons, hung with slender curved leaves. Once or twice a year it opens small pale-green flowers, faintly fragrant towards evening; a moss never blooms, but sheds spores instead. The leaves are clad in tiny silvery scales called trichomes, and those scales are the whole secret of how it lives, since each can pull moisture and specks of dust and mineral straight out of the air.
Where the name comes from
The name is a small historical joke, and wrong twice over. The plant is native to the Americas rather than to Spain, ranging from the southern United States down through Central America to Argentina and Chile. One old story has French settlers naming it "Spanish beard" as a jibe at Spanish explorers, whose long dark beards it was said to resemble, and the Spanish paying them back with "French hair". The "moss" is just the loose English habit of pinning that word on anything low, soft and hanging. Older country names read truer to the eye: graybeard, old man's beard, tree hair. Even its Latin tag admits the muddle, since usneoides means "resembling Usnea", the beard lichen it apes without being any relation to.
How it lives on the tree
People often fear it strangles or feeds on the trees it drapes. It does neither. Spanish moss is an epiphyte, a plant that perches on another only for a foothold and takes nothing from it, living entirely on rain, mist and the dust that settles on it. The oaks and bald cypresses it favours simply offer a bright, humid branch to hang from. A very heavy load can shade a tree's own foliage, or weigh down an already failing limb when it is sodden, but that is the limit of the damage. Dry, it turns pale silver and curls tight; wet, it greens and softens within minutes. That colour change is the plant shifting between resting and drinking, not dying and reviving.
Keeping it at home
This is where it parts company with most of the things wrongly called moss: you can genuinely keep Spanish moss alive indoors, which is more than can be said for reindeer "moss". It wants no pot and no soil whatsoever. Hang a handful somewhere bright but clear of scorching midday sun, keep the air around it moving, and wet it two or three times a week, either by misting it thoroughly or dunking it for half an hour, then letting it dry right out before the next soak. The usual way to kill it is to leave it damp in still, stuffy air, where it rots. Growth is slow, and a contented strand simply lengthens and branches year on year. One word of caution: festoons gathered from the wild can carry chiggers, minute biting mites, so a good rinse and a spell of drying pays off, though nursery-grown material comes clean.
What it has been used for
Long before it was a windowsill curiosity, Spanish moss was harvested as a crop. Cured and ginned much as cotton is, the tough black inner fibre left once the outer tissue has rotted away went into mattresses, cushions, upholstery and, well into the twentieth century, car seats; the early Ford motor cars left the factory with their seats packed with it, until the fibre's knack for sheltering the odd insect saw the practice dropped. It has served as packing, mulch and garden liner besides, and it still earns a living in floristry and in model-railway scenery, prized for the same draping softness that keeps reindeer lichen in demand. In the wild it is a habitat in itself: certain warblers and bats roost and nest among the hanging curtains, and a few small creatures are found almost nowhere else. To meet the other everyday impostor that trips people the same way, the springy grey stuff sold by the bag, turn to reindeer moss; and for the clean line between a real moss and everything that merely borrows the word, there is telling moss apart.