Sago palm
The sago palm (Cycas revoluta), also known as king sago or Japanese sago palm, is a slow-growing, evergreen cycad species that resembles a true palm but belongs to the ancient gymnosperm family Cycadaceae, with origins dating back over 200 million years.[1] Native to the tropical and subtropical regions of southern Japan (including Kyushu and the Ryukyu Islands) and southern China, it features a stout, shaggy trunk up to 1 foot in diameter and a crown of stiff, glossy, dark green, pinnate fronds that arch outward, each reaching 3 to 5 feet long with spiny-tipped leaflets that curl under at the edges.[2] This dioecious plant, requiring separate male and female specimens for reproduction, produces male cones up to 2 feet long or female clusters of furry, globe-like structures bearing bright orange seeds about 2 inches in diameter, typically pollinated from April to June with seeds maturing by September to October.[1] In cultivation, the sago palm thrives in USDA hardiness zones 9a to 11, preferring full sun to partial shade, well-drained sandy or loamy soils with neutral to acidic pH, and moderate watering, though it exhibits strong drought tolerance once established.[3] It grows very slowly, often taking over 50 years to reach 10 feet in height and width outdoors, making it suitable for use as a landscape accent, container plant, or bonsai specimen in subtropical gardens, borders, or indoor settings where it requires bright indirect light and temperatures above 15°F to avoid frost damage.[2] Historically in Japan, the pith of the trunk was processed to extract a starch used as a famine food after thorough detoxification, though commercially, true sago starch is primarily sourced from the unrelated palm Metroxylon sagu to distinguish it from this cycad.[2] Despite its ornamental appeal, the sago palm is highly toxic to humans and animals due to cycasin and other compounds in all parts, particularly the seeds, which can cause severe gastrointestinal distress, liver failure, seizures, and potentially death if ingested without proper preparation.[1] It is susceptible to pests like scale insects, mealybugs, and spider mites, and while female plants are generally non-allergenic, male plants may cause mild skin irritation from pollen.[3] Propagation occurs via offsets or seeds, but due to its toxicity and slow growth, it requires careful handling and is not recommended for households with pets or children.[2]Description
Physical characteristics
The sago palm (Cycas revoluta) is an evergreen cycad with a stout, cylindrical trunk that grows up to 3 meters tall and 30 to 40 centimeters in diameter.[2] The trunk is dark brown, rough-textured, and covered in a thick layer of matted fibers or scales, giving it a shaggy appearance, topped by a rosette of 50 to 150 stiff, arching leaves.[2] These leaves are pinnately compound, reaching 1 to 1.5 meters in length, with glossy dark green leaflets that are linear, 10 to 20 centimeters long, and feature reduced spines at the base, curled margins, and sharply pointed tips.[1] As a dioecious species, it bears separate male and female reproductive structures: males produce a large, upright cone up to 60 centimeters long covered in golden-yellow sporophylls, while females form clusters of leaf-like megasporophylls bearing bright orange, bead-like seeds up to 5 centimeters in diameter.[2]Growth and life cycle
Cycas revoluta is a very slow-growing plant, often taking 50 years or more to reach 10 feet (3 meters) in height.[1] It can live for many decades, with some specimens surviving over 100 years under suitable conditions. Growth occurs primarily through the production of new leaves from the apical meristem, with trunk elongation happening gradually over time.[4] The plant is polycarpic, meaning it can reproduce multiple times without dying after reproduction, unlike monocarpic species. Reproduction is dioecious, requiring male and female plants. Male plants produce a conical structure (strobilus) up to 60 cm long that releases pollen, primarily dispersed by wind or insects. Female plants develop clusters of megasporophylls, each bearing 2–5 ovules that, upon fertilization, develop into bright orange seeds about 5 cm in diameter. Seeds mature over several months and are dispersed by gravity or animals.[1][2] Vegetative propagation occurs naturally through offsets (pups) that develop at the base of the trunk and can be separated to produce new plants. Sexual reproduction from seeds is slower, with germination taking 3–4 months under moist, warm conditions, followed by years of slow juvenile growth before maturity, which may not occur for 15–20 years or longer.[2]Taxonomy and etymology
Scientific classification
"Sago palm" most commonly refers to the cycad Cycas revoluta in the family Cycadaceae, order Cycadales, which are gymnosperms phylogenetically distant from true palms despite superficial resemblances in foliage and form.[2] This species yields sago-like starch from its trunk, though it is not the primary commercial source. In contrast, the term is sometimes applied to true sago palms in the genus Metroxylon within the family Arecaceae, order Arecales, part of the monocotyledonous angiosperms; Metroxylon sagu is the primary source of commercial sago starch.[5][6] The genus Metroxylon comprises approximately seven species.| Taxonomic Rank | Classification |
|---|---|
| Kingdom | Plantae |
| Phylum | Tracheophyta |
| Class | Liliopsida |
| Order | Arecales |
| Family | Arecaceae |
| Genus | Metroxylon Rottb. |
| Species | M. sagu Rottb. |
| Taxonomic Rank | Classification |
|---|---|
| Kingdom | Plantae |
| Phylum | Cycadophyta |
| Class | Cycadopsida |
| Order | Cycadales |
| Family | Cycadaceae |
| Genus | Cycas L. |
| Species | C. revoluta Thunb.; C. circinalis L. |