File:A slime mould - Arcyria nutans - geograph.org.uk - 967636.jpg

English: A slime mould - Arcyria nutans This slime mould species was growing on the soggy wood of a dead tree that was still standing upright; the woods in which the tree stands are not far from a footpath.

In this image, the central portion may resemble baked beans, but this fruiting body is made up of many worm-like individual spore-bearing structures (sporangia) packed closely together (as can be seen at the top, for example). These sporangia are less than 1 cm long, and are much narrower at the base, thus forming a kind of stalk. The whole colony shown here was about 3 or 4 cm high.

[Compare the illustrations of this species on the following page: http://www.nahuby.sk/obrazok_detail.php?obrazok_id=34811 ]

According to Bruce Ing's "The Myxomycetes of Britain and Ireland – An Identification Handbook" (1999), Arcyria nutans is "very common throughout the British Isles", and its habitat is "on fallen trunks and branches, especially of beech, also on dead branches of oak still attached to the tree, occasionally on conifer logs; from mid-summer to late autumn".

[The species is listed in that book as "A. obvelata", but the same author's "A Census Catalogue of The Myxomycetes of Great Britain and Ireland" (2nd edn, 2000) was able to reinstate the more familiar name of A. nutans (see that work for the details).]

I collected a couple of the individual sporangia seen here, and kept them overnight. By morning, their smooth outer layer had disappeared, and they had expanded into delicate loofah-like yellow structures (the link given above also shows these). This illustrates the manner in which the spores are dispersed in nature.

The species name "nutans" means "nodding", and the sporangia are "when mature drooping and loofah-like, to 15 mm tall when fully expanded" [Bruce Ing, in the identification handbook already cited].