orange lichen

Caloplaca adnexa Vězda

Caloplaca adnexa has an orange body, or thallus, divided into tiny lobules about 0.5 mm across. Its original diagnosis describes rounded, disk-like reproductive structures called apothecia set against this finely divided surface. University of Graz Herbarium GZU000287779: Caloplaca adnexa isotype and Vězda diagnosis

Botanical name

Caloplaca adnexa Vězda is retained in the 2025 North American lichen checklist. The supplied Vezda is the same author name without its diacritic. Consortium of North American Lichen Herbaria: Cumulative Checklist, version 24, 2025

Recognizing the plant

The apothecia are 0.5–0.8 mm across, with thick orange margins and darker orange disks that are flat or slightly convex. Under a microscope, the spore-producing layer measures about 120 micrometres deep. Spores are 12–14 by 7–8 micrometres, with two rounded chambers. The partition between them is thin, approximately 2 micrometres, and particularly narrow at its center. University of Graz Herbarium GZU000287779: Caloplaca adnexa isotype and Vězda diagnosis

Native range

The original collection grew on schist at Popova Šapka in the Šar Mountains, now North Macedonia, at about 2,000 metres. The North American checklist supplies another regional record; these occurrences do not define its complete native range. University of Graz Herbarium GZU000287779: Caloplaca adnexa isotype and Vězda diagnosis Consortium of North American Lichen Herbaria: Cumulative Checklist, version 24, 2025

Ecological relationships

In the originally described material, the lichen begins growing in cracks between patches of Rhizocarpon disporum. It eventually destroys these host areoles, replacing parts of the other lichen’s surface. University of Graz Herbarium GZU000287779: Caloplaca adnexa isotype and Vězda diagnosis

Botanical sources

Reviewed 2026-10-11. Seasonal development varies with location and growing conditions.