Their ancestors would have seen the dinosaurs come and go and survived many different climate changes.
At one stage they would have been a dominant feature of forests, deserts and open savannahs in the Jurassic period.
Cycad fossils have been found on every continent including Antarctica and encompass 19 extinct genera of cycads known only as fossils.
There have been many other cycad fossils found but they have not been able to be assigned to any known genera.
Today there are 11 genera and approximately 250 species of cycads found in small populations and distributed throughout many continents in tropical and subtropical regions occupying a wide range of habitats including grasslands, rainforests, deciduous and evergreen forests.
Cycads are still evolving and are capable of responding to environmental change, but the biggest change they have had to deal with is human change.
The destruction of their natural habitats caused by urban spread and deforestation for farming and agriculture, as well as their popularity as collectors' items for plant hunters has had a huge impact in the decline of their numbers in the wild.
Cycads are sometimes thought to be related to palm trees due to their stout trunks and spreading leaves, or ferns because of the way the leaves are arranged or unfurl, but they are not related to either of these plants.
They are more closely related to conifers and the maidenhair tree, Ginkgo biloba because they all produce seed from cones.
Some of the cycads on display in the Winter Garden Glasshouse include Cycas revoluta, probably the most common cycad found in cultivation today due to its tolerance of a variety of conditions and Stangeria eriopus, an endangered cycad from Natal in South Africa, which was first thought to be a fern due to its habit and leaf shape.
It was later identified as a cycad when it produced cones for reproduction and not spores. - Stephen Bishop
Stephen Bishop is curator of the Winter Garden Glasshouse at Dunedin Botanic Garden.
