North America Native Plant

Brooks’ Alsophila

Botanical name: Alsophila brooksii

USDA symbol: ALBR3

Life cycle: perennial

Habit: subshrub

Native status: Native to Puerto Rico  

Synonyms: Cyathea brooksii Maxon (CYBR7)   

Brooks’ Alsophila: A Rare Puerto Rican Tree Fern Worth Knowing If you’ve ever dreamed of adding a touch of prehistoric elegance to your tropical garden, Brooks’ alsophila might just capture your imagination. This remarkable tree fern, scientifically known as Alsophila brooksii, is a living piece of Puerto Rico’s natural heritage ...

Rare plant alert!

Region: Conservation status by state

Status: S1S3: Status is uncertain but is somewhere between the following rankings: Critically Imperiled: Extremely rare due to factor(s) making it especially vulnerable to extinction. Typically 5 or fewer occurrences or very few remaining individuals (<1,000) ⚘ Vulnerable: Either very rare and local throughout its range, found only in a restricted range (even if abundant at some locations), or factors are making it vulnerable to extinction. Typically 21 to 100 occurrences or between 3,000 and 10,000 individuals ⚘

Brooks’ Alsophila: A Rare Puerto Rican Tree Fern Worth Knowing

If you’ve ever dreamed of adding a touch of prehistoric elegance to your tropical garden, Brooks’ alsophila might just capture your imagination. This remarkable tree fern, scientifically known as Alsophila brooksii, is a living piece of Puerto Rico’s natural heritage that brings both beauty and botanical significance to the right garden setting.

What is Brooks’ Alsophila?

Brooks’ alsophila is a perennial tree fern that’s actually classified as a shrub due to its woody, multi-stemmed growth pattern. Don’t let that fool you though – this isn’t your typical backyard shrub! It can reach impressive heights of up to 13-16 feet, creating a dramatic vertical presence with its distinctive trunk and crown of large, feathery fronds that give it that classic prehistoric fern appeal.

You might also see this plant referenced by its synonym, Cyathea brooksii, in older botanical literature, but Alsophila brooksii is the current accepted name.

Where Does It Come From?

This special fern is endemic to Puerto Rico, meaning it naturally occurs nowhere else in the world. It’s found in the island’s mountainous regions, where it thrives in the humid, shaded conditions of tropical forests.

A Word of Caution: Rarity Matters

Here’s something important to know before you fall head-over-heels for this beautiful fern: Brooks’ alsophila has a conservation status of S1S3, which indicates it’s quite rare in its native habitat. While this makes it even more special, it also means we need to be extra thoughtful about how we approach growing it.

If you’re considering adding this fern to your collection, please ensure you source it from reputable nurseries that propagate their plants responsibly rather than collecting from wild populations. Every wild plant matters when a species is this rare!

Is It Right for Your Garden?

Brooks’ alsophila isn’t a plant for everyone, and that’s perfectly okay! This tropical beauty is only suitable for USDA hardiness zones 10-11, which means it’s really only an option for gardeners in consistently warm, humid climates like southern Florida, Hawaii, or similar tropical regions.

Here’s what makes it special in the right setting:

  • Creates stunning vertical interest as a specimen plant
  • Adds authentic tropical character to shade gardens
  • Works beautifully in humid, woodland-style landscapes
  • Provides a unique conversation piece due to its rarity

Growing Conditions

If you’re lucky enough to live in a climate where Brooks’ alsophila can thrive, here’s what it needs to be happy:

  • Light: Filtered shade to partial shade – think dappled sunlight through a tree canopy
  • Moisture: Consistent humidity and regular watering; it’s classified as facultative, meaning it can handle both wet and moderately dry conditions, but prefers consistent moisture
  • Protection: Shelter from strong winds, which can damage the delicate fronds
  • Soil: Well-draining but moisture-retentive soil rich in organic matter

What About Wildlife Benefits?

While we don’t have specific data on Brooks’ alsophila’s wildlife benefits, tree ferns generally provide habitat for various small creatures and can contribute to the overall ecosystem health of tropical gardens. Since this is a fern rather than a flowering plant, it won’t directly attract pollinators, but it can provide shelter and contribute to the humid microclimate that many tropical species appreciate.

The Bottom Line

Brooks’ alsophila is undeniably gorgeous and would make a stunning addition to any tropical garden that can accommodate its needs. However, its rarity means it’s more of a special-occasion plant than an everyday garden choice. If you’re passionate about conservation and have the right growing conditions, seeking out responsibly propagated specimens can be a wonderful way to help preserve this unique piece of Puerto Rico’s natural heritage.

For most gardeners outside tropical zones, appreciating Brooks’ alsophila might be best done through botanical gardens or by supporting conservation efforts in Puerto Rico. But if you do have the opportunity to grow one responsibly, you’ll be caring for a truly special piece of our planet’s botanical diversity.

Brooks’ Alsophila

Classification

Group

Fern

Kingdom

Plantae - Plants

Subkingdom

Tracheobionta - Vascular plants

Superdivision
Division

Pteridophyta - Ferns

Subdivision
Class

Filicopsida

Subclass
Order

Polypodiales

Family

Cyatheaceae Kaulf. - Tree Fern family

Genus

Alsophila R. Br. - alsophila

Species

Alsophila brooksii (Maxon) R. Tryon - Brooks' alsophila

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