Holy Mushrooms

Aharon from Ramot asks:

My wife bought a can of mushrooms with a good hechsher (kosher
certification). However, I was surprised to see that there was no mention of
whether trumos and ma’asros had been separated nor was there any
mention of sh’mittah. Could you please enlighten me?

Mushrooms may be popularly considered a vegetable, but they are really very
different. They do grow on the ground, but not from the ground. They have no
roots and take their nourishment from the moisture in the air. There is
therefore no obligation to take trumos and ma’asros from
mushrooms. For the same reason, they have no kedushas shvi’is and the
prohibition of s’fichin does not apply to them. The correct berochoh
(blessing) on mushrooms is shehakol, and not ho’adomoh.
Nevertheless, when buying canned mushrooms one should ensure that they have a
good hechsher for two reasons: (a) they are cooked with steam, which may
previously have been used for non-kosher products, such as soup (b) there may be
other ingredients which present kashrus problems. (Source: Minchas
Yitzchok, Vol.8, No.99, from the Me’iri to Avodah Zoro
14b.)