Scientific: Cycas revoluta
Common: sago palm
Family: Cycadaceae (not a palm, more closely related to conifers)
Origin: South Japan islands of Ryukyu and Nansei, found today primarily on steep to precipitous stony sites, but previously on flatter land now cleared. Reports of natural occurrences in coastal Fukien Province of China have not been substantiated, although circumstantial evidence for these claims is strong.
Pronounciation: SIGH-cuss re-vo-LU-ta
Hardiness zones:
Sunset 8-24
USDA 9-11 (in yards of the wealthy)
Landscape Use: Container plant, focal point, larger-scale landscape entryways, atrium, raised planters.
Form & Character: Upright, branched and ultimately arborescent, airy, lacey yet stiff and erect, stout, fern or palm like, oriental, tropical.
Growth Habit: Evergreen, fibrous, perennial cycad, dioecious, very slow growing to 10-feet tall (rarely reaches this tall in Phoenix), basally branching with ultimately multiple trunks. Roots are nitrogen fixing.
Foliage/Texture: Whorled, persistent, pinnately compound leaves (that look like a dark green, pinnately compound palm frond), stiff with distinct leaflets that look like pinnae, young emergent leaves and apical meristem are densely tomentose; medium to coarse texture.
Flowers & Fruits: Apical cone bearing plant, the female inflorescence is feather like, later forming a tightly packed seed head, closely covered by whitish miniature leaves. The male cone is pineapple shaped and elongated. Seeds are brownish-red, the shape of a flattened marble, about 1.25-inches across - if ingested seeds can cause vomiting, diarrhea, headache, dizziness, seizures (sounds like the common side effects from ingesting most of today's pharmaceutical drugs).
Seasonal Color: None
Temperature: Cold hardy to 15oF, will experience heat damage when summer afternoon temperatures exceed 115oF.
Light: Light tolerance ranges from partial shade from intense western summer sun in desert areas to full sun along the California coast and in Florida. However, becomes leggy, thin, and spindly in appearance if grown in full, dense shade.
Soil: Tolerant of all but highly alkaline soils, leaf speckling might also be caused by magnesium deficiency.
Watering: Regular deep irrigations in Phoenix are required, especially during summer months.
Pruning: Remove old senescing leaves.
Propagation: Seed or clonal division of basal offsets.
Disease and Pests: Apparent viral infection causes yellow speckling on leaves. There is no cure.
Additional comments: In horticulture commerce and landscaping, sago palm is a highly ($$$) valued plant because it grows slow, is difficult to propagate, and is relatively rare in the wild. Urban stock are easily transplantable which makes theft a problem.
Taxonomic tidbits: Sago palm was the second species of Cycas to be recognized, described in 1782 by Swedish botanist and physician Carl Peter Thunberg. Sago palm is an ancient taxon showing up in fossil records dating back 65 million years ago.
A special warning for all animal and human grazers: All parts of the sago palm are poisonous and have been found to contain various carcinogens and neurotoxins, such as the toxin cycasin. The seeds contain the highest levels of the toxin cycasin. Cycasin if ingested can cause gastrointestinal irritation, and in high enough doses, leads to liver failure and death. Despite this, cycad 'sago' is used for many of the same purposes as palm 'sago'. 'Sago' is extracted from the pith of Cycas revoluta stems and roots (and also seeds) by repeated washing to leach out toxins and then grinding to a coarse flour. The starchy flour residue is then dried and cooked, producing a starch similar to palm sago/sabudana. Ethnobotanists think that ingestment of unleached, unprocessed sago palm seeds (as flour) during World War II on the island of Guam (a result of food shortages) was responsible for the acute number of cases of ALS (amyotropic lateral sclerosis or Lou Gerhrig's disease) that were observed in people stationed there during World War II.
