^{(photo above: Barrel cactus fruit and black seeds, Jason)}

Additional Reading: Cactus Seed Germination

Opuntia macrorhiza fruit with seeds, Tony Frates

Barrel cactus fruit with dried flower, David Leonard

Pitaya fruits, Sam Blackman

Astrophytum myriostigma seeds, Kathy

Tiny actus seedling with seed coat , Peter Baur

Echinocactus polycephalus xeranthermoides seed, USGS

Echinocactus polycephalus polycephalus seed, USGS