How many basidiospores are produced by each basidium?

The number of basidospores per basidium is generally four, although it’s not uncommon to find two spores per basidium. Some species produce more than four; in Phallus impudicus, there can be 9 spores per basidium.

Sources:

• An Introduction to Mycology (Mehrotra and Aneja)

• Fungi and Allied Organisms (Sharma)