Encephalartos

Male cones are elongated, and three or four may appear at a time. Female cones are borne singly, or up to three at a time, and may weigh up to 60 pounds (27 kg). In some species, male cones with ripe pollen emit a nauseating odour. When the pollen has been shed and the males cones decay, a strong odour of acetic acid has also been noted.[6]

Colonies of the cyanobacterium Nostoc punctiforme occur in apparent symbiosis inside the root tissue,[6] while the rootlets produce root tubercles at ground level which harbour a mycorrhizal fungus of uncertain function,[6] which is however suspected to facilitate the capturing of nitrogen from the air.[7]

In several species the pith of the trunk contains a copious amount of high quality starch below the crown. This was formerly cut out by native people as food. Thunberg recorded around 1772 that the Hottentots removed the stem's pith at the crown and buried it wrapped in animal skin[7] for about two months, after which they recovered it for kneading into bread,[6] whence the vernacular name "broodboom" (i.e. bread tree). The burial of the pith apparently facilitated its fermentation and softening,[6] and the dough was lightly roasted over a coal fire.[8] In 1779 Paterson likewise found that the pith of a "large palm" near King William's Town was utilised by the Africans and Hottentots as bread. The pith was removed and left till sourish, before it was kneaded into bread.[6][9]

Their large seeds consist of an often poisonous kernel covered by an edible fleshy layer.[7] Female cones are consequently destroyed by baboons, as they relish the pith around the seeds.[6] Vervet monkeys, rodents and birds also feed on the seeds, but due to their unpredictable toxic qualities they are not recommended for human consumption.[7]

The early larval instars of some aposematic, day-flying looper moths are specific to cycads, and genus Encephalartos is one of their food plants.[10] They include the leopard magpie (most Encephalartos spp., other cycads, etc.), Millar's tiger (cultivated E. villosus), dimorphic tiger (cycads under forest canopy), spotted tigerlet (E. villosus), inflamed tigerlet (E. villosus), Staude's tigerlet (E. ngoyanus, cultivated E. villosus and Stangeria) and pallid grey (E. natalensis).[11]

In cultivation various scale insects attack the leaves of the genus. These include cycad aulacaspis scale, zamia scale and latania scale.[12]