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Barton Lab

Island defense · Endemic Hawaiian flora

The Pua Kala Project

A luminous white flower armed with prickles, bright latex, and a remarkably flexible defense strategy.

Explore the project View research data

Project summary

Defense, built in layers

Pua kala (Argemone glauca) is Hawaiʻi’s endemic prickly poppy. Its conspicuous defenses make it a powerful system for testing a persistent idea in island biology: that island plants evolve weak defenses because they experience less pressure from herbivores.

Since 2010, the Barton Lab has examined how prickles, latex, epicuticular waxes, and tolerance vary among populations, across plant development, after herbivory, and in response to light and water availability. Together, these traits reveal a defense strategy that is dynamic rather than fixed.

Endemicfound naturally only in Hawaiʻi
3+complementary defense mechanisms
2010project research began

Defense toolkit

More than just prickly

Pua kala combines structural, chemical, and whole-plant responses—each changing with environment and life stage.

Young pua kala seedling with sharply lobed leaves
01

Prickles

Physical barriers vary strikingly among populations and can become stronger after damage.

Bright orange latex emerging from a cut pua kala stem
02

Latex

Bright orange latex provides a rapid chemical response when stems or leaves are damaged.

Pua kala plant with waxy blue-green leaves
03

Waxes & tolerance

Epicuticular waxes and the ability to regrow broaden defense beyond deterrence alone.

Open research resources

Explore the data

Interactive map

Explore pua kala sampling locations across Hawaiʻi.

Interactive plots

Compare traits and environmental patterns.

Sampling sites

Open the project’s site-level spreadsheet.

Environmental context

External data sources

Statewide environmental layers help connect variation in defense traits with climate, geology, elevation, and protected landscapes.

Annual rainfall

Giambelluca, T. W., et al. 2013. Online Rainfall Atlas of Hawaii. Bulletin of the American Meteorological Society 94: 313–316.

Citation KML

Geologic age

Sherrod, D. R., et al. 2007. Geologic map of the State of Hawaii. USGS Open-File Report 2007-1089.

Source KML

Elevation

1983 USGS Digital Elevation Models obtained through the Hawaiʻi Statewide GIS Program.

Source KML

Rain gauges

Rain summary locations supplied by the National Weather Service in Honolulu.

Source KML

Reserves and protected lands

Reserve, preserve, and park boundaries obtained through the Hawaiʻi Statewide GIS Program.

Source KML

Further reading

References

Hoan, R. P., R. A. Ormond, and K. E. Barton. 2014. Prickly poppies can get pricklier: ontogenetic patterns in the induction of physical defense traits. PLoS ONE 9(5): e96796. PDF

Barton, K. E. 2014. Prickles, latex and tolerance in the endemic Hawaiian prickly poppy (Argemone glauca): variation between populations, across ontogeny and in response to abiotic factors. Oecologia 174: 1273–1281. PDF

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