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  • Paula Ogilvie

Up in the Air

By Paula Ogilvie:

Perhaps this past holiday season you received a small gray-green air plant as a gift – or treated yourself to one as a way to overcome the winter doldrums. But what exactly are air plants?

Tillandsia bromeliad growing on an oak in Puebla, Mexico
Tillandsia bromeliad growing on an oak in Puebla, Mexico

These small plants, often 2-6 inches long, are mostly comprised of twisty grayish-green leaves, a small bulb-shaped body, and no root system at all. Yes, they are alive. Their botanical name is Tillandsia, a genus of over 650 species of flowering plants in the Bromeliad family. While this popular family is actually named for the terrestrial pineapple, most of the members of the family don’t grow in the soil but up on tree branches.

Plants that grow on another plant for support but not nutrition are called epiphytes (epi means upon, phyte means plant). The tiny roots, which are not always present, actually help the plant cling to a support plant. Air plants often grow in clusters and can be found nestled in branches. Epiphytes are not parasites; their leaves are photosynthetic, producing the plants’ needed food.

Since epiphyte refers to a lifestyle, the term is applied to many plants including most bromeliads, most orchids, ferns such as the staghorn, and many begonias. The term air plant is commonly used for the tiny Tillandsias.

Tillandsias range from the southern United States through Mexico, Central and South America, and the Caribbean islands. Perhaps the most famous is Spanish Moss (Tillandsia usneoides), with its long hanging tresses of entwined leaves that drape over tree branches in humid locations.

Air plants usually grow in humid areas though they have adapted to many environments. A few grow in the desert-like environments of some coastal regions where they derive moisture from fog and condensation in the evenings. Their roots, when present, help them to stay anchored. The leaves, covered with microscopic hairs that shade the plants and impart a grayish color, are modified to absorb moisture from the air and nutrients from decaying leaves and insects that fall on them.

Growing them in Colorado homes can be a challenge. They require bright light but no direct hot sun, humidity but not wet conditions, and good air circulation. Do not plant them in soil; they truly are air plants. A bathroom window or kitchen window near the sink where humid air from the dishwasher will help are both good locations. Keep temperatures above 45 degrees. Most homes have some of these conditions.

I’ve seen air plants growing in tiny, open, clear terrariums, in shells or other small hanging pots. Combined with the plants’ unique shapes these architectural pots can be striking. The trick is keeping them humid but not wet. Consider placing them in the sink once a week, watering well, then shaking off any excess water and returning them to their container. More adventurous gardeners might secure them to a branch for a more natural look.

Look for plants that are firm with healthy leaves and check for rot. Popular in the 1970s, many new Tillandsias were bred so it is likely you won’t find a botanical name with the plants. Some have a bulb shape with long strap-like leaves. Make sure that water doesn’t accumulate in the bulb. Others may have a blush of reddish color on the leaf tips adding to their interesting shape. Flowers are small but often colorful shades of white, rosy-pink or bluish-purple, and they may produce feathery seeds. The leaves may also add color when the plants bloom. While not grown for their flowers, tillandsias will re-bloom unlike larger bromeliads. Just cut off the flowers once they are finished blooming. Some air plants will produce small plantlets at the base, called pups, after blooming. Either leave them attached or break off to start in a new container.

Plants that grow on another plant for support but not nutrition are called epiphytes.

I used to bring a few air plants home from my sister’s southern yard along with some Spanish moss. The Spanish moss died almost immediately even though I manage to grow orchids that bloom repeatedly bloom without a greenhouse. The air plants survived a bit longer - until I forgot to mist them. So this year’s resolution is to try again with a few interesting Tillandsias.

A couple of other fun oddities…

Marimo moss balls in their natural habitat, Lake Akan, Japan
Marimo moss balls in their natural habitat, Lake Akan, Japan

Moss Balls

When shopping at fancier plant shops, I’ve noticed “moss balls” growing in bowls of water. Though they look like moss, they are actually a type of algae that grows in ball form. Called Marimo moss balls, they can be safely grown in a fresh water aquarium or in a water bowl by themselves. First identified in the early 1800s, they are found in northern hemisphere lakes in Japan and Iceland. Interestingly, this species of algae grows in round colonies where wind, currents and low light conditions help maintain the rounded shape.

Moss balls are very slow growers adding only a few millimeters per year. Given the proper conditions, they might grow for a century. Their care is simple: clean water (allow chlorine to dissipate overnight before adding moss balls to a container), occasionally squeeze the balls gently (mimicking wave action in nature), and rotate them so all sides receive sunlight. They will grow in lower light, not direct sun, so this might be an interesting and beautiful winter project to set up in a glass container or fish tank.

Air ferns are the dead, dried skeletons of a marine animal known as  sea fir. Dyed green, the coloring will dissolve in water.
Air ferns are the dead, dried skeletons of a marine animal known as sea fir. Dyed green, the coloring will dissolve in water.

Air Ferns are brightly colored novelties sold as low maintenance plants. But they aren’t plants! Air ferns are the skeletons of small marine “animals” that lived in a colony. Collected by fishing vessels, the now dead colonies resemble a fern’s branching fronds but they have been dyed a bright green. If you mist them the dye comes off. Hopefully, you won’t get one; these are only for friends who can’t grow anything.

Paula Ogilvie is a science advisor at Community College of Denver who has taught biology, botany, and botany for gardeners.

All photos: Wikimedia Commons



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