Zamioculcas

Zamioculcas is a genus of flowering plants in the family Araceae, containing the single species Zamioculcas zamiifolia. It is a tropical herbaceous perennial plant, and is native to eastern Africa, including Kenya, KwaZulu-Natal, Malawi, Mozambique, Tanzania, and Zimbabwe. Its common names include Zanzibar gem, ZZ plant, Zuzu plant, aroid palm, eternity plant and emerald palm. It is grown as a houseplant, mainly because it has attractive glossy foliage and is easy to care for. Zamioculcas zamiifolia is winter-hardy in USDA Zones 9 and 10.

Dutch nurseries began wide-scale commercial propagation of the plant around 1996. It was first described in 1829 by Loddiges, who named it Caladium zamiifolium; Heinrich Wilhelm Schott later reassigned it to the genus Zamioculcas, and Adolf Engler renamed it Zamioculcas zamiifolia.

Etymology
The genus Zamioculcas derives its name from the similarity of its foliage to that of the cycad genus Zamia and its kinship to the Araceae genus Colocasia, whose name comes from the word “” or “” (from an ancient Middle Eastern name), and which is named qolqas (قلقاس, ) in Arabic. Botanical synonyms include Caladium zamiaefolium, Zamioculcas loddigesii and Z. lanceolata.

The species name Zamiifolia means "leaves like Zamia" and is formed from the botanical name Zamia and the Latin word folium, "leaf."

Cultivars



 * Zamioculcas zamiifolia 'HANSOTI13,' commercially known as 'Zenzi'
 * Zamioculcas zamiifolia 'Dowon,' commercially known as 'Raven',  is licensed by Costa Farms.
 * Zamioculcas zamiifolia 'Super Nova'
 * Zamioculcas zamiifolia ‘Chameleon’

Growth pattern
It is an herbaceous perennial growing to 45–60 cm tall, from a stout, underground, succulent rhizome. It is normally evergreen but becomes deciduous during drought, surviving drought due to the large potato-like rhizome that stores water until rainfall resumes.

The most visible "branches" are actually smooth, shiny, dark green, pinnately compound leaves. These are 40–60 cm long, with swollen, succulent petioles and 6–8 pairs of leaflets, each 7–15 cm long. Zamioculcas zamiifolia grows slowly, reaching heights and widths ranging from 2 to 4 feet.

Inflorescence
The flowers are produced in a small, bright yellow to brown or bronze spadix 5–7 cm long and wrapped in a yellow-green spathe; the whole inflorescence is partly hidden among the branch bases. Flowering is from midsummer to early autumn.

Leaves
Zamioculcas zamiifolia contains 91% water in the leaves, and 95% water in the petioles. It has an individual leaf longevity of at least six months, which may be the reason it can survive extremely well under interior low light levels for four months without water.

Temperature
It may survive outdoors as long as the temperature does not fall below around 15 C; though best growth is between 18 and 26 C, while high temperatures give an increase in leaf production. In temperate regions, it is grown as a houseplant. Overwatering may destroy this plant through tuber rot. Bright, indirect light is best; some sun will be tolerated.

Propagation
Zamioculcas zamiifolia may be propagated by leaf cuttings: typically, the lower ends of detached leaves are inserted into a moist, gritty growing medium, and the pot is enclosed in a polythene bag. Though the leaves may well decay, succulent bulb-like structures should form in the bag, and these may be potted up to produce new plants. The process may take upwards of one year. The plant can also be propagated by division.

Light
Due to its strong green leaves, it is especially suitable for open, bright rooms. When grown indoors, the plant prefers bright indirect light but will tolerate low light conditions. However, lower light is not optimal for an extended period of time. Insufficient amounts of sunlight can result in leaves lengthening and/or falling off, yellowing (chlorosis), and generally uneven or disproportionate growth as the plant stretches towards a light source. When grown outdoors, Zamioculcas zamiifolia prefers part shade to full shade.

Soil
The substrate used must be well-drained and contain nutrients. It can be composed of a mixture of tanned ox manure, washed river sand and red earth (1:1:1). For indoor plants, use a well-drained potting soil mix.

Water
Zamioculcas zamiifolia roots are rhizomatous and have the ability to store moisture, thus aiding the plants in their drought resistance. The plants like regular waterings, but the soil should be allowed to dry out between waterings.

Usage in traditional medicine
Though little information is available, Z. zamiifolia is apparently used medicinally in the Mulanje District of Malawi and in the East Usambara mountains of Tanzania where juice from the leaves is used to treat earache.

In Tanzania, a poultice of bruised plant material from Z. zamiifolia is used as a treatment for the inflammatory condition known as "mshipa".

Roots from Z. zamiifolia are used as a local application to treat ulceration by the Sukuma people in north-western Tanzania.

Chemicals
Zamioculcas zamiifolia contains acylated C-glycosylflavone apigenin 6-C-(6″-O-(3-hydroxy-3-methylglutaroyl)- β-glucopyranoside).

Air purification
A 2014 study from the Department of Plant and Environmental Science at the University of Copenhagen shows that, in a laboratory setting, the plant is able to remove volatile organic compounds in this order of effectiveness: benzene, toluene, ethylbenzene and xylene at a molar flux of around 0.01 mol/(m2 day). The same study stated that any effectiveness on indoor environments is inconclusive.

Toxicity
Zamioculcas zamiifolia is part of the family Araceae, which includes many poisonous genera, such as Philodendron, Monstera, Anthurium, Dieffenbachia, Aglaonema  and  Spathiphyllum, all of which contain insoluble calcium oxalate.

An initial toxicological experiment, conducted by the University of Bergen in 2015, on extracts from Z. zamiifolia (using brine shrimp as a lethality assay), did not indicate lethality to the shrimp, even at concentrations of extracts up to 1 mg/mL. The scientists conducting the experiment observed that, "…On the contrary, it could appear as though the extract contributed to improvements in the vitality of the larvae".