The genus Xylaria

 

 

Xylaria aff. aristata (B00-024), Ouagadougou, Burkina Faso (© JHP)

Unfortunately without mature spores. Macroscopically a fairly close match to X. aristata, but could represent another taxon.

 

Xylaria or Dead man's fingers is a genus with mostly upright, clavate or strap-like stromata. As in most other genera the ascospores are dark-coloured with a germ slit that can be running along the whole axis of the spore or be variously modified including destinctly spiral. Again as in most genera, the apical apparatus in the asci stain blue in iodine reagents. The inner stroma is mostly very firm and white, but some taxa have hollow, sap-filled cavities and others yellow or even blackish colours.

The number of known species of Xylaria in Africa exceeds 50, but I suspect the true number to much higher. As in South East Asia some species are associated with termites, although the specific nature of this relationship is unknown (see some of the pictured examples). Xylaria species, although most often encountered on woody substrates, also to a large extend colonize substrates such as woody legume pods and other kinds of fruit, petioles and herbaceous stems.

Anamorps: mostly in the form of compact palisades of conidiophores (Nodulisporium/Geniculisporium-like) on immature stromata.

Important references: Scattered, but see Dennis (1958, 1961, 1962, 1963, 1964 - listed at the Xylariales page)

 

 

 

 

Xylaria arenicola Welw. & Curr. (B00-023), Ouagadougou, Burkina Faso (© JHP)

One of those species that possibly has an asssociation with termites. This is one of the very few collections known of this very interesting taxon. Note the highly variable stromatal shape .

 

 

Xylaria sp. (B00-018), Ouagadougou, Burkina Faso (© JHP)

Unfortunately in the anamorphic, very hard to name, state with a very young teleomorph developing.

 

 

Xylaria poitei (Lev.) Fr. (B00-073), Ouagadougou, Burkina Faso (© JHP)

One of the more common African Xylarias, certainly one of those with the most impressive stromata. It has a rather smooth surface and wrinkles strongly upon drying due to a high water content. It may be related to Xylaria cubensis s.l. rather than to the Xylaria polymorpha series.

 

 

Xylaria sp. (B00-077), Ouagadougou, Burkina Faso (© JHP)

Again a 'rooting' species that may be termite associated. It is almost certainly an undescribed species.

 

 

Xylaria sp. (Pat.) Dennis (B00-085), Ouagadougou, Burkina Faso (© JHP)

Also a species that 'root' and may or may not be termite asscociated. I have found no matching species so probably represents an undescribed species.

 

 

Xylaria ustorum (B00-050), Ouagadougou, Burkina Faso (© JHP)

This very unual species with unknown affinities within the genus also has a very interesting ecology being found exclusively on burnt grass rhizomes.