Haplotrichum pulchrum

This grew on damp, well-rotted eucalypt wood in a suburban garden. It has a fairly open-weave type of growth, with some similarity to fairy floss in terms of appearance and softness, and about as easy to photograph as fairy floss! Here masses of asexual spores are being produced, colourless when immature and lemon yellow at maturity. My estimate of abundance is arbitrary and likely to be wrong. Counting spore-producing structures such as mushrooms, puffballs, brackets on wood, etc is fairly easy since the individual structures are often easy to tell apart. In this case I have no idea as to whether this mass of 'fairy-floss' is one or a hundred separate structures.

I have studied this specimen microscopically to determine the species. The material (as collection number: HL6120) is now at the Australian National Herbarium, Canberra.

I have added a composite picture showing microscopic features. I rehydrated a small fragment in a potassium hydroxide solution (a colourless liquid, so the greyish background colours that you see here are photographic artefacts). In the fluffy mass that you see with the naked eye, there are numerous conidiophores (upright hyphae that produce the asexual spores, or conidia). The conidiophore’s apical cell may be narrow or swollen and from it several noticeable prongs protrude. Inset at the upper left of Photo 3 I show one such swollen cell. Three prongs protruding to the left are easy to see and the white arrow points to a fourth that is protruding towards you. A conidium is produced on each prong and sometimes such a conidium may have a prong (or a few) on which a further conidium (or conidia are produced). I did not see the process continue any further, so no chains of conidia. Inset at the lower left you see two joined conidia. The upper one has developed on a prong on the lower one and at the bottom of the lower conidium you see a slight bump, the point at which it was attached to the conidiophore. Inset at the lower right I show a few free-floating conidia. Conidia may also be produced on prongs that protrude from non-apical cells and the arrows in Photo 4 point to a few examples. In this specimen the conidia were colourless to pale yellow, 12.8-19.2x 9.6-15.2 microns and (apart from possible prongs) had a smooth surface.