Tokyo Food Safety Information Center » Good things to know »  Poisonous plants easily mistaken for harmless ones » Cycas revoluta (Cycadaceae)

Cycas revoluta (Cycadaceae)

Evergreen tree with a stem that grows from 1 to 4 meters. Dioecious plant that grows a flower on the tip of the trunk in the summer. At a glance, its form is similar to a palm, but it is a gymnosperm related to ginkgo, cedar and similar. Its ripe seed is large in size, cinnabar red with glossy outer seed coat.


Habitat Besides growing in southern Kyushu and Okinawa, it is cultivated in all regions.
Parts of the plant that may be ingested accidentally. Seeds, etc.
Symptoms Vomiting, dizziness, breathing difficulties, etc.
Venomous constituents Seeds contain glycoside cycasin. When disintegrated in the body after ingestion, it produces formaldehyde and causes poisoning.

Cycas revoluta
Cycas revoluta
Cycas revoluta seed
Cycas revoluta seed


Bureau of Public Health, Tokyo Metropolitan Government
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