North America Native Plant

Treetrunk Spleenwort

Botanical name: Asplenium auriculatum

USDA symbol: ASAU2

Life cycle: perennial

Habit: forb

Native status: Native to Puerto Rico  

Treetrunk Spleenwort: A Delicate Caribbean Fern for Tropical Gardens Meet the treetrunk spleenwort (Asplenium auriculatum), a charming little fern that’s as unique as its name suggests. This delicate perennial fern brings a touch of tropical elegance to any shaded garden space, though it’s definitely not your typical backyard plant. If ...

Treetrunk Spleenwort: A Delicate Caribbean Fern for Tropical Gardens

Meet the treetrunk spleenwort (Asplenium auriculatum), a charming little fern that’s as unique as its name suggests. This delicate perennial fern brings a touch of tropical elegance to any shaded garden space, though it’s definitely not your typical backyard plant. If you’re lucky enough to garden in a tropical climate or have a greenhouse setup, this Caribbean native might just steal your heart.

Where Does Treetrunk Spleenwort Come From?

This lovely fern calls Puerto Rico home, where it grows naturally as an epiphyte – that means it likes to live on other plants (usually trees) rather than in the ground. It’s perfectly content perching on tree trunks and branches, soaking up the humid Caribbean air. Being a true Puerto Rican native, it’s perfectly adapted to the island’s tropical conditions.

What Makes This Fern Special?

The treetrunk spleenwort is all about subtle beauty. Its delicate, feathery fronds create an almost lace-like appearance that adds texture and movement to any planting scheme. The distinctive auriculate or ear-like shape of its leaflets gives it character that sets it apart from other ferns. Don’t expect dramatic size – this is a petite beauty that makes its impact through grace rather than grandeur.

Is It Right for Your Garden?

Here’s where things get a bit tricky. This fern is quite the diva when it comes to growing conditions. It thrives in:

  • USDA hardiness zones 10-12 only
  • High humidity environments
  • Shaded locations with indirect light
  • Well-draining but consistently moist conditions

If you live outside of these tropical zones, don’t despair! The treetrunk spleenwort can make a stunning addition to a greenhouse or terrarium setup where you can control the humidity and temperature.

Growing Your Treetrunk Spleenwort

Since this is an epiphytic fern, traditional planting advice goes out the window. Instead of soil, think mounting! Here’s how to keep your treetrunk spleenwort happy:

  • Mount it on cork bark, tree fern slabs, or grow it in a very chunky, well-draining epiphytic mix
  • Keep humidity levels high (50-70% or more)
  • Provide bright, indirect light – never direct sunlight
  • Water regularly but ensure excellent drainage to prevent root rot
  • Maintain warm temperatures year-round

Garden Design Ideas

In tropical shade gardens, the treetrunk spleenwort works beautifully as part of an epiphyte collection mounted on tree trunks or garden structures. It pairs wonderfully with other small tropical ferns, bromeliads, and orchids. For those in cooler climates, it makes an excellent greenhouse specimen or terrarium resident.

Wildlife and Environmental Benefits

As a fern, the treetrunk spleenwort reproduces through spores rather than flowers, so it won’t directly attract pollinators. However, it does contribute to the overall ecosystem by providing shelter for small creatures and adding to the biodiversity of tropical gardens. Its facultative wetland status means it’s adaptable to varying moisture conditions, making it a resilient choice for Caribbean landscapes.

The Bottom Line

The treetrunk spleenwort is definitely a specialty plant for dedicated tropical gardeners or fern enthusiasts. While it requires specific conditions to thrive, those who can provide the right environment will be rewarded with a unique and graceful addition to their plant collection. If you’re new to growing epiphytic ferns, you might want to start with hardier species, but if you’re up for the challenge, this Puerto Rican beauty is absolutely worth the effort.

Wetland Status

The rule of seasoned gardeners and landscapers is to choose the "right plant for the right place" matching plants to their ideal growing conditions, so they'll thrive with less work and fewer inputs. But the simplicity of this catchphrase conceals how tricky plant selection is. While tags list watering requirements, there's more to the story.

Knowing a plant's wetland status can simplify the process by revealing the interaction between plants, water, and soil. Surprisingly, many popular landscape plants are wetland species! And what may be a wetland plant in one area, in another it might thrive in drier conditions. Also, it helps you make smarter gardening choices and grow healthy plants with less care and feeding, saving you time, frustration, and money while producing an attractive garden with greater ecological benefits.

Regions
Status
Moisture Conditions

Caribbean

FAC

Facultative - Plants with this status can occur in wetlands and non-wetlands

Treetrunk Spleenwort

Classification

Group

Fern

Kingdom

Plantae - Plants

Subkingdom

Tracheobionta - Vascular plants

Superdivision
Division

Pteridophyta - Ferns

Subdivision
Class

Filicopsida

Subclass
Order

Polypodiales

Family

Aspleniaceae Newman - Spleenwort family

Genus

Asplenium L. - spleenwort

Species

Asplenium auriculatum Sw. - treetrunk spleenwort

Plant data source: USDA, NRCS 2025. The PLANTS Database. https://plants.usda.gov,. 2/25/2025. National Plant Data Team, Greensboro, NC USA