North America Non-native Plant

Castilla

Botanical name: Castilla elastica costaricana

USDA symbol: CAELC

Native status: Not native but doesn't reproduce and persist in the wild

Synonyms: Castilla panamensis O.F. Cook (CAPA66)   

Castilla: The Mysterious Costa Rican Rubber Tree You Probably Haven’t Heard Of If you’re the type of gardener who loves discovering rare and unusual plants, you might find yourself intrigued by Castilla elastica costaricana, commonly known simply as castilla. This lesser-known variety of rubber tree carries an air of botanical ...

Castilla: The Mysterious Costa Rican Rubber Tree You Probably Haven’t Heard Of

If you’re the type of gardener who loves discovering rare and unusual plants, you might find yourself intrigued by Castilla elastica costaricana, commonly known simply as castilla. This lesser-known variety of rubber tree carries an air of botanical mystery that’s both fascinating and, well, a bit frustrating for those of us who like our plant facts neat and tidy.

What Exactly Is Castilla?

Castilla elastica costaricana is a subspecies of the Panama rubber tree, and as its scientific name suggests, it’s associated with Costa Rica. You might also see it referenced by its synonym, Castilla panamensis O.F. Cook, which can add to the confusion when you’re trying to track down information about this elusive plant.

Here’s where things get interesting (and by interesting, I mean challenging): specific information about this particular variety is surprisingly scarce. While its parent species, Castilla elastica, has been cultivated and studied, the costaricana subspecies remains something of an enigma in the horticultural world.

Where Does It Come From?

Based on its scientific name and the limited information available, this castilla variety appears to be native to Costa Rica, likely thriving in the country’s diverse tropical ecosystems. However, without more detailed distribution data, it’s difficult to pinpoint exactly where you might encounter this plant in its natural habitat.

Should You Grow Castilla in Your Garden?

This is where I have to be completely honest with you: the lack of specific cultivation information for Castilla elastica costaricana makes it a risky choice for most home gardeners. Here’s what we’re dealing with:

  • Unknown hardiness zones and climate requirements
  • Unclear growth habits and mature size
  • Uncertain soil and water preferences
  • Unknown pest and disease susceptibilities
  • Unclear propagation methods

The Reality Check

While the idea of growing a rare Costa Rican rubber tree variety might sound appealing, the practical challenges are significant. Without reliable information about its growing requirements, invasive potential, or even basic care needs, attempting to cultivate this plant becomes more of a botanical experiment than a gardening project.

If you’re drawn to the idea of growing unusual rubber trees or plants with tropical origins, you might want to consider better-documented alternatives that can provide the exotic appeal you’re seeking without the guesswork.

A Word of Caution

If you do somehow encounter Castilla elastica costaricana for sale or trade, proceed with extreme caution. Always ensure any plant material is:

  • Legally and ethically sourced
  • Free from pests and diseases
  • Accompanied by proper documentation
  • Appropriate for your local climate and growing conditions

The Bottom Line

Castilla elastica costaricana remains one of those plants that’s more interesting as a botanical curiosity than as a practical garden addition. While there’s something undeniably appealing about rare and unusual species, the lack of reliable growing information makes this particular variety better left to botanical gardens and specialized researchers who can properly study and document its needs.

For most gardeners, focusing on well-documented native species or thoroughly researched non-native plants will yield better results and fewer headaches. Sometimes the most responsible thing we can do as gardeners is to admire a plant’s mystery from afar rather than attempting to solve it in our own backyards.

Castilla

Classification

Group

Dicot

Kingdom

Plantae - Plants

Subkingdom

Tracheobionta - Vascular plants

Superdivision

Spermatophyta - Seed plants

Division

Magnoliophyta - Flowering plants

Subdivision
Class

Magnoliopsida - Dicotyledons

Subclass

Hamamelididae

Order

Urticales

Family

Moraceae Gaudich. - Mulberry family

Genus

Castilla Cerv. - castilla

Species

Castilla elastica Sessé - Panama rubbertree

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