A. asiaticus A. hygrometricus A. koreanus A. morganii A. odoratus A. pteridis A. sirindhorniae A. smithii A. telleriae Astraeus is a genus of fungi in the family Diplocystaceae.

[2] They are distinguished by the outer layer of flesh (exoperidium) that at maturity splits open in a star-shape manner to reveal a round spore sac.

[5] Astraeus species are strongly hygroscopic, and absorb moisture from the environment, so that the rays are closed over the spore case when dry, but open up flat when moistened.

[10] However, studies in the 2000s showed that species collected from around the world and labelled under the specific epithet hygrometricus were actually considerably variable in a number of macroscopic and microscopic characteristics.

Currently, eight species are recognized:[12][13] In 2008, five lanostane-type triterpenes were isolated and identified from the fruit bodies of A. pteridis; two of these compounds had an inhibitory effect on the growth of the pathogen Mycobacterium tuberculosis.