Xanthomendoza ulophyllodes

Family: Teloschistaceae

Powdery Sunburst Lichen (Xanthomendoza ulophyllodes) is a bright yellow to orange foliose lichen distinguished from other Minnesota sunbursts by its well-developed lower surface with conspicuous white rhizines. These attachment structures are the most reliable field character separating it from superficially similar species.

This page documents Research Grade observations on iNaturalist using photos E21A8109-8136 and E21A8111A. Visual presentation and artistic interpretation are handled separately in the Gallery.

This species is less frequently encountered than Xanthomendoza fulva but can form robust, visually striking colonies where conditions are favorable.

Description

The thallus is foliose and moderately thick, forming irregular rosettes or spreading patches. Lobes are broad, uneven, and often somewhat inflated, with margins that may curl or lift slightly from the substrate.

The upper surface is yellow to yellow-orange, frequently appearing powdery or granular due to abundant soredia. Apothecia may be present but are often sparse or absent in heavily sorediate specimens.

The lower surface is pale and bears distinct white rhizines, frequently branched or tufted, which anchor the lichen firmly to bark.

Substrate and Habitat

Xanthomendoza ulophyllodes is typically found on:

Tree bark, especially hardwoods
Trunks and branches in open to lightly wooded settings

It often grows as a dominant patch rather than being tightly interwoven with other lichens, giving colonies a more self-contained appearance.

Identification Notes

Key diagnostic features include:

True rhizines visible along the lower surface or emerging beneath lobe margins
Powdery, sorediate upper surface
Thicker, more three-dimensional thallus than most other sunbursts

This species is most commonly confused with Bare-bottomed Sunburst (Xanthomendoza fulva), which:

Lacks true rhizines
Is more thinly attached to the substrate
Often grows embedded in mixed lichen communities

Care should be taken not to confuse rhizines with moss rhizoids, bark fibers, or fungal hyphae, which may appear as white threads but do not originate from the lichen’s lower surface.

Ecology and Notes

Like other members of the Teloschistaceae, Xanthomendoza ulophyllodes contains protective pigments that allow it to tolerate high light exposure. Its rhizinate attachment suggests a preference for more stable bark substrates, where firmer anchoring provides an advantage.

Confirmed observations in Minnesota are less common than those of X. fulva, making well-documented records particularly valuable.

References

Consortium of Lichen Herbaria
iNaturalist (Research Grade observations)
Brodo, I. M., Sharnoff, S. D., & Sharnoff, S. (2001). Lichens of North America