Key to Cycad Genera
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Note:
The smaller genera have keys to species adapted from
Jones, D.
L. 1993. Cycads of the World. Smithsonian Institution Press, Washington, D.C.; click on the genus name to
view. For the larger genera--i.e., Cycas, Encephalartos, and Zamia--the link will take you
to the keys in The Cycad Pages. |
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| 1 | Leaves
bipinnate Leaves pinnate |
Bowenia Go to 2 |
| 2 | Leaflets
with a prominent midrib Leaflets lacking a prominent midrib |
Go to 3 Go to 5 |
| 3 | Leaflet
margins entire, lateral veins absent Leaflet margins irregular or toothed, lateral veins present |
Cycas Go to 4 |
| 4 | Lateral
veins arising at right angle to midrib Lateral veins arising at acute angle to midrib |
Stangeria Chigua |
| 5 | Leaflets
attached to upper surface of rhachis Leaflets attached to margins of rhachis |
Lepidozamia Go to 6 |
| 6 | Swollen,
often colorful small patch of callous tissue at base of upper
leaflet margin Colorful callous tissue absent from the base of upper leaflet margin |
Macrozamia Go to 7 |
| 7 | Leaflets
not jointed to rhachis, cataphylls present on cone stalk Leaflets jointed to rhachis, cataphylls absent on cone stalk |
Go to 8 Go to 9 |
| 8 | Sporophyll
ends faceted, seeds attached directly to sporophyll, leaflets
weakly decurrent on rhachis Sporophyll ends not faceted, seeds attached to sporophylls by a basal stalk, leaflets strongly decurrent on rhachis |
Encephalartos Dioon |
| 9 | Leaflets
reflexed, prickles absent on petiole and rhachis Leaflets spreading, prickles present or absent on petiole and rhachis |
Microcycas Go to 10 |
| 10 | Sporophylls with two horns, leaflets entire Sporophylls lacking horns, leaflets with teeth or entire |
Ceratozamia Zamia |
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