CYCADACEAE

The Cycadaceae is an ancient plant family that has existed since the age of dinosaurs. It comprises of a single genus Cycas, with some 100+ tropical Old World species. Unlike flowering plants  (angiosperms), Cycadaceae is a non-flowering gymnosperm. Cycads do not produce flowers that develop into fruits with enclosed seeds. Instead, they produce cones containing open-air seeds that are not visible until maturity. The genus Cycas is dioecious, there is an individual male and female plant, each bearing male and female cones, respectively. Cycas leaves are palm-like, pinnate, and arranged in a rosette. The apex consists of hardened scale leaves, which develop slowly into matured leaves.

All Cycadaceae species are poisonous due to the presence of a  toxin called cycasin. Once ingested, cycasin breaks down into highly reactive compounds that damage the DNA, causing death by multi-organ failure or cancer. Cycadaceae also harbours symbiotic relationship with cyanobacteria, which produces a neurotoxic amino acid called beta-methylamino-L-alanine (BMAA). Despite the apparent toxicity, humans consume the starchy stem of many Cycas species, particularly the sago palm (misnomer!), Cycas revoluta. Careful processing is required to quench the reactive cycasin by hot water (hydrolysis). Cycas spp. are cultivated worldwide as landscaping plants. They are particularly toxic to domestic dogs, which tend to consume the seeds with fatal consequences. 

Japanese sago palm (Cycad revoluta)