# Dendrographa

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***Dendrographa*** is a [genus](/source/Genus) of [lichen](/source/Lichen)-forming [fungi](/source/Fungi) in the family [Roccellaceae](/source/Roccellaceae).[1] It has seven species.[2] These lichens form small, shrubby tufts that cling to bark or coastal rocks along the Pacific seaboard, with brown-grey main branches and paler, pencil-thin tips that lack a protective outer skin. The genus was originally established in 1895 for a single Pacific coast species, but [molecular](/source/Molecular_phylogenetics) studies in the 2010s expanded it by transferring four additional species from other genera and led to the discovery of a seventh species in Brazil.

## Taxonomy

The genus *Dendrographa* was [circumscribed](/source/Circumscription_(taxonomy)) by the British lichenologist [Otto Vernon Darbishire](/source/Otto_Vernon_Darbishire) in 1895 to accommodate the distinctive Pacific-coast lichen then known as *Roccella leucophaea*; Darbishire recognised that its [fruticose](/source/Fruticose_lichen) habit, branch tips and [calcium oxalate](/source/Calcium_oxalate)-encrusted [medulla](/source/Medulla_(lichenology)) set it apart from *[Roccella](/source/Roccella_(lichen))* and related genera. He therefore transferred the species as *Dendrographa leucophaea* and designated it the [type species](/source/Type_species) of his new genus.[3]

For more than a century *Dendrographa* was treated as [monospecific](/source/Monospecific) until Sundin and Tehler's 1996 [monograph](/source/Monograph) combined detailed [morphology](/source/Morphology_(biology)) with [thin-layer chromatography](/source/Thin-layer_chromatography) to define the genus more precisely and to describe a second species, *D. alectoroides*. Their study also documented two informal forms produced by [vegetative](/source/Vegetative_reproduction) fragmentation, emphasising that the genus was characterised by the absence of specialised propagules ([isidia](/source/Isidia) or [soredia](/source/Soredia)) and by [protocetraric acid](/source/Protocetraric_acid) chemistry.[4]

[Molecular phylogenetics](/source/Molecular_phylogenetics) work in the early 2010s reshaped the genus. A broad rDNA/RPB2 analysis of the [Arthoniales](/source/Arthoniales) by Ertz and Tehler showed that four sorediate species previously scattered in *[Roccellina](/source/Roccellina)*, *[Dirina](/source/Dirina)* and allied genera actually nested within the *Dendrographa* [clade](/source/Clade); they were therefore transferred as *D. conformis*, *D. decolorans*, *D. franciscana* and *D. latebrarum* in 2011.[5] The decade closed with the description of *D. austrosorediata* from wave-washed granite in southern Brazil—the first member of the genus recorded outside the north-eastern Pacific—which expanded the genus to seven accepted species.[6]

## Description

*Dendrographa* lichens form small, shrubby ([fruticose](/source/Fruticose_lichen)) tufts that cling to bark or coastal rock along the Pacific seaboard of [Baja California](/source/Baja_California) and [California](/source/California). The main branches are brown-grey and often flattened near the base, but the younger, pencil-thin tips—and the many side that burst through the surface—lack a protective skin () and appear paler, with a fine white, powdery bloom (). Branches sometimes fuse to one another, and broken tips readily re-establish elsewhere, helping the lichen spread. A tightly packed outer of parallel fungal threads ([hyphae](/source/Hypha)) encloses a looser inner [medulla](/source/Medulla_(lichenology)); some specimens accumulate tiny [calcium oxalate](/source/Calcium_oxalate) crystals.[4]

The genus does not produce dedicated vegetative [propagules](/source/Propagule) such as [soredia](/source/Soredia) or [isidia](/source/Isidia), so reproduction relies chiefly on sexual fruit bodies ([ascomata](/source/Ascomata)) and accidental fragmentation. Ascomata are small lateral , 0.3–3 mm across, that erupt through the cortex and eventually sit on a narrow base; their exposed surface is smooth, white and often slightly domed, ringed by a pale margin of cracked cortex. Each [ascus](/source/Ascus) contains eight colourless, three-segmented (3-septate) spindle-shaped [ascospores](/source/Ascospore), roughly 22–24 μm long by 6–8 μm wide, which are shot into the air when mature. Tiny black [pycnidia](/source/Pycnidia)—flask-shaped cavities sunken in the thallus—exude curved [conidia](/source/Conidia) about 11–15 μm long. The [photosynthetic](/source/Photosynthesis) partner is the orange-tinged green alga *[Trentepohlia](/source/Trentepohlia_(alga))*, whose cells (10–20 μm) are scattered throughout the interior.[4]

All examined specimens contain [protocetraric acid](/source/Protocetraric_acid) as their principal [secondary metabolite](/source/Secondary_metabolite), sometimes accompanied by trace amounts of [fumarprotocetraric](/source/Fumarprotocetraric_acid) and [succinprotocetraric acids](/source/Succinprotocetraric_acid); these closely related compounds are thought to deter [grazers](/source/Grazing) and mitigate [ultraviolet](/source/Ultraviolet) stress.[4]

## Species

- *[Dendrographa alectoroides](/source/Dendrographa_alectoroides)* Sundin & Tehler (1996)[4]
- *[Dendrographa austrosorediata](/source/Dendrographa_austrosorediata)* Aptroot & Gumboski (2017)[6] – Brazil
- *[Dendrographa conformis](/source/Dendrographa_conformis)* (Tehler) Ertz & Tehler (2011)
- *[Dendrographa decolorans](/source/Dendrographa_decolorans)* (Turner & Borrer) Ertz & Tehler (2011)
- *[Dendrographa franciscana](/source/Dendrographa_franciscana)* (Zahlbr.) Ertz & Tehler (2011)
- *[Dendrographa latebrarum](/source/Dendrographa_latebrarum)* (Ach.) Ertz & Tehler (2011)
- *[Dendrographa leucophaea](/source/Dendrographa_leucophaea)* (Tuck.) Darb. (1898)

## References

1. Wijayawardene, Nalin; Hyde, Kevin; Al-Ani, Laith Khalil Tawfeeq; Somayeh, Dolatabadi; Stadler, Marc; Haelewaters, Danny et al. (2020). "Outline of Fungi and fungus-like taxa". *Mycosphere*. **11**: 1060–1456. [doi:10.5943/mycosphere/11/1/8](https://doi.org/10.5943/mycosphere/11/1/8). [hdl:10481/61998](https://hdl.handle.net/10481/61998)

1. Darbishire, O.V. (1895). ["*Dendrographa*, eine neue Flechtengattung"](https://www.biodiversitylibrary.org/page/42092846) (in German). *Berichte der Deutschen Botanischen Gesellschaft*. **13**: 313–326.

1. Sundin, Rikard & Tehler, Anders (1996). "The genus *Dendrographa* (Roccellaceae)". *The Bryologist*. **99** (1): 19–31. [doi:10.2307/3244433](https://doi.org/10.2307/3244433). [JSTOR 3244433](https://www.jstor.org/stable/3244433)

1. Ertz, D. & Tehler, A. (2011). "The phylogeny of Arthoniales (Pezizomycotina) inferred from nucLSU and RPB2 sequences". *Fungal Diversity*. **49** (1): 47–71. [doi:10.1007/s13225-010-0080-y](https://doi.org/10.1007/s13225-010-0080-y)

1. Aptroot, André; Gumboski, Emerson Luiz; Cáceres, Marcela Eugenia da Silva (2017). "Ocean view: a first assessment of the littoral, crustose lichen biota of south Brazil". *The Lichenologist*. **49** (6): 597–605. [Bibcode:2017ThLic..49..597A](https://ui.adsabs.harvard.edu/abs/2017ThLic..49..597A). [doi:10.1017/s0024282917000512](https://doi.org/10.1017/s0024282917000512)

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Adapted from the Wikipedia article [Dendrographa](https://en.wikipedia.org/wiki/Dendrographa) by Wikipedia contributors ([contributor history](https://en.wikipedia.org/wiki/Dendrographa?action=history)). Available under [Creative Commons Attribution-ShareAlike 4.0 International](https://creativecommons.org/licenses/by-sa/4.0/). Changes may have been made.