A cascading plant that evokes images of the Louisiana Bayou, sold at local garden centres, is flourishing in certain parts of Australia.
Spanish moss (Tillandsia usneoides), sometimes also known as ‘Old Man’s Beard’, is an ethereal hanging plant with silver-green leaves and fragrant flowers. It’s also, despite its name, not a moss but rather a flowering air plant (epiphyte) belonging to the bromeliad family (related to pineapples).
Native to humid places such as south-eastern United States, Central America, South America and the Caribbean, Spanish moss drapes dramatically over other tree branches and requires only air and moisture — and no soil — to survive.
It’s often used in floral decorations, and even packaging and stuffing. Fun fact: Spanish moss was used in the upholstery of the first Model-T Ford cars.
It sounds like a gorgeous addition to any garden – and many gardeners love it. But it’s worth noting that it can damage its host plants and, in Australia, Spanish moss is considered an environmental weed.
It’s currently proliferating across native trees and bushland on Sydney’s North Shore, around Lismore on the NSW North Coast and on Lord Howe Island where it threatens the island’s unique World-Heritage-Listed ecosystems.
An environmental weed is considered to be any plant – whether introduced or native – that invades natural ecosystems and can harm native wildlife, plant communities, or ecological functions.
Spanish moss is not currently listed as a prohibited or restricted plant under NSW biosecurity laws, nor is it listed as a priority weed under regional plans like the Greater Sydney Regional Strategic Weed Management Plan.
The more serious category of invasive weed (or invasive plant) is specifically reserved for non-native (exotic) species that spreads rapidly on its own into new areas and causes economic, environmental, or health damage.
Spanish moss has also been found in Queensland and some Pacific Islands.
Why is Spanish moss such a menace?
While Spanish moss isn’t a parasite, it spreads easily, and its leaves can damage host trees by shading their branches from the sun.
Those heavy cascades of pretty, silvery tendrils can also weigh down the limbs of native foliage, such as turpentines, brush box and lilly pilly. It’s growing more rapidly on our eastern seaboard due to warmer and wetter climate conditions.
Spanish moss seeds, which are light and fluffy, can get picked up by the wind and stick to tree branches. From there, they spawn new plants. “Its weedy potential is highlighted by how easily the plant spreads from one place to another without human intervention, including being spread by birds,” a spokesperson for the NSW Department of Primary Industries and Regional Development told Better Homes and Gardens.
What can we do about Spanish moss?
Willoughby City Council, on Sydney’s Lower North Shore, recently urged its constituents to check gardens for Spanish moss and to remove it, if safe to do so.
They also recommended not use it for landscaping or decoration, even though it’s readily available to buy in garden centres and online. “Spanish moss is becoming an environmental threat in our urban forest,” said Mayor Tanya Taylor. “Early action and strong community cooperation are essential to protect the health of our tree canopy and local biodiversity.”
Spanish moss isn’t the only potentially problematic plant being sold in retailers. Not-for-profit organisation Invasive Species Council (ISC) estimates there are thousands of species on the Australian market that can jump your fence, so to speak, and impact local bushland. These include gazania (Gazania spp.), mock orange (Murraya paniculata), duranta (Duranta erecta), English ivy (Hedera helix) and the popular snake plant or mother-in-law’s tongue (Sansevieria trifasciata).
Old varieties of Agapanthus (Agapanthus praecox) are invasive. Newer cultivars are bred to be sterile or set significantly fewer seeds to prevent them from escaping into bushland. Vegetative spread is still possible, even if a variety has sterile seeds many types can still spread and multiply underground through their thick tubers and root clumps.
So, next time you’re shopping for new plants or seeds, take a moment to research the species and find out if it’s a weed in your region. And if you can’t resist the lure of dreamy Spanish moss or hardy purple agapanthus, do your best to prevent it from spreading beyond your property.
The lead image accompanying this article is of Spanish moss in a Jacaranda tree, photographed in Sydney, Australia. (credit: Rupert Bickersteth).
“Old Man’s Beard”
“Old man’s beard” is a common or vernacular name for several different trailing, fuzzy, or white-bearded plants, based on what they look like. The name is shared by a few completely different species:
- Some lichens like Usnea hang from tree branches
- The seed pods of clematis like Traveller’s Joy (Clematis vitalba or Clematis aristata)
- Fluffy flowering plants like fringe tree (Chionanthus virginicus)
- Air plants like Spanish moss (Tillandsia usneoides) from the bromeliad family
