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8.3: Cycads

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    Cycads (Phylum Cycadophyta)

    Cycads are easy to recognize because they look like a palm tree. However, they bear large cones rather than fruits. Their leaves are quite large compared to the stem and grow out in a rosette around the stem (Figure 8). They can be either male or female, and their cones vary in shape and size, depending on the species. There are approximately 340 species worldwide (Christenhusz and Byng, 2016) and are native to tropical and subtropical areas. They can grow in deserts as well as wet forests. Even though we don’t have any native cycad species in Hawai‘i, you have probably seen them around homes, botanical gardens, and parks.

    There are two main families of cycads: Cycadaceae and Zamiaceae (another family, Stangeriaceae, has only two living species). Many cycad species are endangered in their natural habitat, although some species are very common in cultivation.

    Cycads by DutraElliott.jpg
    Figure \(\PageIndex{1}\): Examples of cycad species growing in Hawai'i. By DutraElliott is licensed under CC BY-NC-SA 4.0 via Flickr.

    The seeds in some cycad species are considered toxic and can negatively affect humans by entering the food cycle through bats, which eat the seeds. Humans then eat the bats, acquiring the poison through second-hand exposure. Another interesting characteristic of cycads is that their roots form a special relationship with bacteria that are able to fix nitrogen.

    This page titled 8.3: Cycads is shared under a CC BY-NC-SA 4.0 license and was authored, remixed, and/or curated by Daniela Dutra Elliott & Paula Mejia Velasquez.

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