M. riedlei benefits from a close association with bacteria that fix nitrogen, which also produce substances found throughout the plant that are toxic to some animals when consumed.

[4] The first species description was published as Cycas riedlei by Friedrich Ernst Ludwig von Fischer, based on a specimen collected at King George Sound and held at the Paris museum.

reidlei— was used by the revising author, Charles Gardner, when assigning it to the genus Macrozamia and citing specimens obtained near Collie, Manjimup, Bow Bridge, and other sites south of Perth.

Macrozamia riedlei is mentioned as causing sickness in men eating the seeds by Vlamingh in 1697, La Perouse in 1788, Flinders in 1801, and Sir George Grey in 1839.

[12]The Willem de Vlamingh incident, the earliest episode of a European poisoning themselves with an Australian plant, was recorded as an unsigned entry in the ship's journal, the officer being one of several who ventured to eat the seeds while exploring the Swan River area.

Ingestion of the unprepared seed induced vomiting after several hours, that was described as putting those afflicted as so bilious there "was hardly any difference between us and death".

Some crew members of the circumnavigation expedition led by Matthew Flinders made a similar error, consuming the toxins of M. riedlei while anchored at the south coast.

Charles Fremantle testily records that despite witnessing and being informed of the consequences of eating the same, many of the men and two officers did just that and some suffered severe reactions.

[5] The misadventure of George Grey's party occurred 13 April 1839, while undertaking a journey to Perth after being shipwrecked on Gantheaume Bay at Kalbarri.

[14] The species known as by-yu and djiriji was an important plant to the Noongar people once processed, the flesh around the seeds a staple food;[15][16] this is comparable with the use of many cycads around the world.

Aside from finding the foodstuff at Noongar camps, or offered it when hungry, early visitors and colonists recorded people harvesting the fruit.

[6] The preparation of the seeds is a method known to the people as mordak, an excavation at a cave in Cape Le Grand national park of a nearly intact example was dated at thirteen thousand years old.

[21] The birds include a western rosella subspecies (moyadong, Platycercus icterotis icterotis) which eat the fleshy part of the seed cone,[22] other birds known to eat the seeds include the emu, common bronzewing pigeon (Phaps chalcoptera), white-tailed black cockatoo, and common species silvereye, grey butcherbird and raven (wodang; Corvus coronoides).

[25] The distribution of the zamia in the southwest has been correlated to sites of long term human habitation, close to lakes or springs, and freshwater points at granitic outcrops of the kwongan, although the intervention of other consumers, birds and mammals, complicates a postulate that inadvertent or intentional cultivation is the primary factor in seed dispersal.

[6] The fruiting cone begins to fully ripen and break apart during the local season bunuru, which occurs between February and March, and is ready to harvest.