Cycas revoluta, the Sago Cycad, is a cycad native to southern Japan, but is now grown worldwide. Though often known by the common name of King Sago Palm, or just Sago Palm, it is not a palm at all, but a type of gymnosperm.
This very symmetrical plant supports a crown of shiny, dark green leaves on a thick shaggy trunk that is typically about 20 cm in diameter, sometimes wider. The trunk is very low to subterranean in young plants, but lengthens above ground with age. It can grow into very old specimens with 6-7 m of trunk, however, the plant is very slow-growing and requires about 50-100 years to achieve this height. Trunks can branch multiple times, thus producing multiple heads of leaves.
The leaves are a deep semiglossy green and about 50-150 cm long when the plants are of a reproductive age. They grow out into a feather-like rosette to 1 m in diameter. The crowded, stiff, narrow leaflets are 8-18 cm long and have strongly recurved or revolute edges. The basal leaflets become more like spines. The petiole or stems of the Sago Cycad are 6-10 cm long and have small protective barbs that must be avoided.
Propagation of Cycas revoluta is either by seed or by removal of basal offsets. As with other cycads, it is dioecious, with each specimen bearing either male or female cones. Pollination of receptive female cones can be done naturally by insects or artificially.
Cultivation and uses
Cycas revoluta grows best in sandy, well-drained soil, preferrably with some organic matter. It needs good drainage or it will rot. It is fairly drought-tolerant and grows well in full sun or outdoor shade, but needs bright light when grown indoors. Leaf color can bleach somewhat in full sun.
The pith is very rich in edible starch, and is used for making sago. Before use, the starch must be carefully washed to leach out toxins contained in the pith.
Of all the cycads, the Sago Palm is the most popular in horticulture. It is seen in almost all botanical gardens, in both temperate and tropical locations. In many areas of the world it is heavily promoted commercially as a landscape plant. It is also quite popular as a bonsai plant. First discovered in the late 1700’s, it is native to various areas of southern Japan and is thus tolerant of mild to somewhat cold temperatures, provided the ground is dry. Frond damage can occur at temperatures below −5° C. It does however require hot summers, with mean temperatures of 30° to 35°C, for successful growth, making outdoor growing impossible in e.g. northern Europe even where winter temperatures are not too cold.
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