Volvariella volvacea

The straw mushroom is a highly valued edible fungus. Its scientific name is *Volvariella volvacea*. It is also called the paddy straw mushroom. This species is cultivated throughout East and Southeast Asia. It is used extensively in many Asian cuisines. In fact, it is the third-most-consumed mushroom worldwide. People often eat them fresh in regions where they are grown. In other parts of the world, they are found canned or dried.

Cultivating these mushrooms follows a very specific process. Farmers grow them on beds made of rice straw. They thrive best in subtropical climates. These regions must have high annual rainfall to be successful. The mushrooms grow at a very rapid rate. They take only four to five days to reach maturity. Most farmers pick them while they are still immature. This is known as the button or egg phase. They are harvested before the veil ruptures.

Identifying these mushrooms requires careful attention to detail. In their button stage, they look like poisonous death caps. This resemblance can be very dangerous for foragers. However, mycologists use spore prints to tell them apart. A spore print is the color left by a mushroom's spores. Straw mushrooms produce a pink spore print. In contrast, death caps produce a white spore print. This distinction is vital for safety.

Misidentification has led to serious health problems. Death caps and straw mushrooms have different natural distributions. Death caps are generally not found where straw mushrooms grow natively. However, people have moved between regions. Immigrants from Southeast Asia have moved to places like California and Australia. Some people have been poisoned there due to misidentification. Always check the spore print color to ensure safety.

History shows that these mushrooms have a long tradition of use. There is no record of their cultivation before the 19th century. They are also used in specialized food production. For example, they play a role in making dark soy sauce. This is called *cǎogū lǎochōu*. Workers mix mushroom broth into the soy sauce during aging. The mixture is then exposed to the sun. This process gives the sauce a richer flavor than plain dark soy sauce.

Straw mushrooms are also very nutritionally dense. One cup of these mushrooms provides significant food energy. They contain 6.97 grams of protein and 4.5 grams of total dietary fiber. They are also a good source of several minerals. One cup provides 27.7 μg of selenium. This is 50.36% of the Recommended Dietary Allowance (RDA). They also provide 699 mg of sodium, which is 46.60% of the RDA.

Other essential nutrients are found in every cup. They contain 2.6 mg of iron, which is 32.50% of the RDA. They also offer 0.242 mg of copper, or 26.89% of the RDA. Other nutrients include 69 μg of vitamin B9 (folate) and 111 mg of phosphorus. You can also find 0.75 mg of vitamin B5 (pantothenic acid). Finally, they provide 1.22 mg of zinc, which is 11.09% of the RDA. These many nutrients make them a powerful part of a diet.