Paddy straw mushroom

What the mushroom is

Volvariella volvacea is a gilled fungus that decomposes plant residue. It is known as the paddy straw mushroom, and its scientific synonyms include Volvaria volvacea, Agaricus volvaceus and Volvariopsis volvacea. The catalogue treats Volvariella volvacea as a research name and does not validate it against the current taxonomic authorities, so the synonyms are kept as search aliases.

The fruiting body rises from a grey, egg-shaped sac called the volva. As it matures the volva splits and the cap and stem emerge. The cap is grey to brownish, the gills are free and turn pink as the spores mature, and there is no ring on the stem. The flesh is white and does not change colour when cut.

In the market it is sold as a fresh, canned or dried culinary mushroom. Sources describe its flavour as mild, slightly sweet and nutty, with a soft texture.

Straw, cotton waste and cultivation

The fungus grows naturally on decomposing straw, compost heaps and rotting wood in warm, humid places. Cultivation began on rice straw, the substrate that gave the mushroom its common name. Sources also name sugarcane bagasse and other cellulose waste as substrates.

A change of substrate marked the modern history of the crop. Cotton waste from ginning mills replaced rice straw in Hong Kong around 1971 to 1973. The source that records this describes it as the turning point for yields, which became higher and more stable. Cultivation then became semi-industrialized in Hong Kong, Taiwan, Indonesia, China and Thailand.

Growers in India are usually credited with the first cultivation in 1940 at Coimbatore, with systematic spawn-based production from 1943 onward.

History of cultivation

The sources do not agree on when the mushroom was first cultivated. The most common account dates cultivation in China to 1822, when Buddhist monks are said to have grown it at Nanhua Temple, and records a tribute shipment to the Chinese imperial court by 1875. Another source says cultivation probably began before the eighteenth century. A less rigorous source places cultivation in the Tang dynasty, around 700 to 900 AD. None of these dates is confirmed here, and they should be read as the claims of their sources.

Overseas Chinese communities are credited with carrying the cultivation to the Philippines, Malaysia and South Asia in the 1932 to 1935 period. The sources are less precise about the routes and the people involved.

Look-alikes and identification

The main hazard named in the sources is the young button stage. Before the cap opens, the fungus looks like a death cap (Amanita phalloides), which is one of the most toxic mushrooms known. The two are separated in the field by the spore print: the straw mushroom has a pink spore print, and the death cap has a white one. Sources report poisonings when people who had moved from Southeast Asia took death caps for the straw mushroom in California and in Australia.

The catalogue gives the warning that immature Amanita can be fatal look-alikes, and that cultivated supply still needs correct identity. A market or cultivation record does not, by itself, establish that a wild specimen is safe to eat. Identification from the appearance of a young fruiting body alone is not reliable, and this page does not offer an identification or a safety verdict for wild material.

Use and preparation

The supplied catalogue records the food uses as fresh, canned and dried mushrooms, and the cultivated supply as the main source. Sources say the young egg-stage fruiting body is prized for its texture, and that the mushroom is used in soups, stir-fries, hot pots, curries and noodle dishes, mainly in Chinese and Southeast Asian cooking.

The sources give no tested storage times or temperatures for the fresh mushroom, so none are stated here.

Open questions

The species records in the catalogue are research labels. The catalogue flags the Chinese listing as a research lead rather than an independent safety assessment. The dates of the first cultivation disagree between sources and have not been checked against primary records. What remains unknown is which cultivated strains are sold under the common name in each market.