Cycadaceae: Cycads

Family Characters:

Habit***: pachycaul, unbranched, palm-like (old leaf-bases remain), dioecious trees

Leaves***: pinnately compound; developing like ferns....(circinate vernation)

Ovules: in cones on peltate scales or on edges of modified leaves

Sperm: largest known (300 um); motile with spiral band of flagella; sex determined by X and Y chromosomes

Seeds: covered with fleshy seed coat

Diversity: 10 genera / ca. 100 species of the tropics in 1 family (older texts) or 3 families (the more recent treatments) :

• --Cycadaceae (pinnae with no lateral veins; Cycas, ca. 20 spp., sago-palm)
• --Stangeriaceae (pinnae with simple lateral veins; 1 sp., Stangeria eriopus)
• --Zamiaceae (pinnae with numerous parallel or wavy, simple or forked veins; 8 genera, 85 species)

Distribution: tropics world-wide
Economics: all cultivated ornamentals and endangered through over-collecting; some yield sago (starch for bread in India)

Representative species found in Arizona:

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