Epipremnum aureum

Epipremnum aureum / Money plant is a species in the arum family Araceae, native to Mo'orea in the Society Islands of French Polynesia. The species is a popular houseplant in temperate regions but has also become naturalised in tropical and sub-tropical forests worldwide, including northern South Africa, Australia, Southeast Asia, South Asia, the Pacific Islands and the West Indies, where it has caused severe ecological damage in some cases.

The plant has a number of common names including golden pothos, Ceylon creeper, hunter's robe, ivy arum, silver vine, Solomon Islands ivy, and taro vine. It is also called devil's vine or devil's ivy because it is very hardy and stays green even when kept in the dark. It is sometimes simply labelled Pothos, or mistakenly labelled as a Philodendron or Scindapsus in plant stores. It is commonly known as a money plant in many parts of Asia. It rarely flowers without artificial hormone supplements; the last known spontaneous flowering in cultivation was reported in 1964.

The plant has gained the Royal Horticultural Society's Award of Garden Merit.

History and etymology
This species has been assigned to a number of genera. In 1880 when it was first described, it was named Pothos aureus, which is why it is often commonly referred to as a "pothos". After an inflorescence was observed in 1962, it was given the new name of Rhaphidophora aurea. However, after closer examination of the flower, researchers noticed its heightened similarity to Epipremnum pinnatum and synonymised it with that species. Only after closer observation of the entirety of the plant, including the leaves and growth patterns, did researchers again separate it from E. pinnatum, and classify it as E. aureum.

Description
Epipremnum aureum is an evergreen vine growing to 20 m tall, with stems up to 4 cm in diameter, climbing using aerial roots which adhere to surfaces. The leaves are alternate, heart-shaped, entire on juvenile plants, but irregularly pinnatifid on mature plants, up to 100 cm long and 45 cm broad; juvenile leaves are much smaller, typically under 20 cm long.

The flowers are produced in a spathe up to 23 cm long. This plant produces trailing stems when it climbs up trees and these take root when they reach the ground and grow along with it. The leaves on these trailing stems grow up to 10 cm long and are the ones normally seen on this plant when it is cultivated as a potted plant.

Shy-flowering nature
While E. aureum is classified as an angiosperm, which typically produce flowers at some point in their life cycle, it is the only reported species in its family (Araceae) that does not readily bloom, if at all. Regardless of where this “shy-flowering” plant is grown, or what the conditions are like, it will apparently not flower due to a genetic impairment of the gibberellin (GA) biosynthetic gene, EaGA3ox1. This impairment causes the plant to be unable to develop bioactive GAs, which are responsible for the flowering of plants, via the floral meristem identity gene EaLFY. In E. aureum, the floral meristem identity gene expression is absent due to the lack of GAs from EaGA3ox1. It was found that when GAs were experimentally sprayed onto the plant, flowering was induced. Thus, it is likely safe to assume that none of the plants seen in modern cultivation have truly been grown from seed. However, it is far more efficient to simply multiply an existing plant by dividing it; the species is well-known for its ease of propagation via vegetative growth, developing roots rapidly through cuttings, either rooted in water or grown directly in a well-aerated substrate, such as perlite mixed with vermiculite, or even sphagnum moss. Additional methods of propagation include whole-plant divisions or root divisions, as well as tissue culture propagation.

Distribution
Originally, it was endemic to the island of Mo'orea from the Society Islands. However, it is now wild in many tropical countries. The following ranges are indicated: Bangladesh, India, Myanmar, Thailand, Vietnam, Hainan, Hong Kong, Taiwan, Japan, peninsular Malaysia, Sabah, Sarawak, Singapore, Java, Maluku Islands, Nusa Tenggara, Sulawesi, Sumatra, Philippines, Solomon Islands, Vanuatu, New Caledonia, New Guinea, Queensland, Marshall Islands, Hawaii, Palau, Fiji, Tonga, Cook Islands, and Western Samoa.

Cultivation and uses
In temperate regions, it is a popular houseplant with numerous cultivars selected for leaves with white, yellow, or light green variegation. It is often used in decorative displays in shopping centers, offices, and other public locations largely because it requires little care and is also attractively leafy. In tropical countries, it is found in many parks and gardens, and tends to grow naturally.

As an indoor plant it can reach more than 2 m in height if given the adequate support (a trellis or moss pole to climb), but hardly develops adult-sized leaves. The best results are achieved by providing indirect light; it tolerates an intense luminosity, but long periods of direct sunlight burn the leaves. It lives well with a temperature between 17 and 30 C. Generally, the plant will only need watering when the soil feels dry to the touch (typically once every one to two weeks). A liquid fertilizer can be added in the spring and it must be replanted every two years, or when it becomes too rootbound. However, it is a very robust plant, and will survive bad growing conditions. The plant grows rapidly in hydroponic culture.

It can be cultivated from a cutting, however, this can carry various diseases such as Erwinia leaf spot, Pythium root rot, Rhizoctonia root rot (Rhizoctonia foot rot), Pseudomonas leaf spot, Southern blight, and Xanthomonas blight.

The plant can remove indoor pollutants such as formaldehyde, trichloroethene, toluene, xylene, and benzene in controlled circumstances (e.g. a sealed room). A study found that this effect declined as the molecular weight of the polluting substance increased.

The plant is sometimes used in aquariums, placed on top of the aquarium, and allowed to grow roots in the water. This is beneficial to the plant and the aquarium as it absorbs nitrates, using them for growth.



Cultivars
There are several cultivars known in the houseplant community. Common varieties include 'Golden Pothos', 'Neon', 'N'Joy', 'Pearls n' Jade', 'Marble Queen', 'Jade', 'Manjula', 'Global Green', and 'Jessenia'.

Toxicity
The plant is listed as toxic to cats and dogs by the ASPCA, because of the presence of insoluble raphides. Care should be taken to ensure the plant is not consumed by pets. Symptoms may include oral irritation, vomiting, and difficulty in swallowing.

Due to the calcium oxalate within the plant, it can be mildly toxic to humans as well. Possible side effects from the consumption of E. aureum are atopic dermatitis (eczema) as well as burning and/or swelling of the region inside of and surrounding the mouth. Excessive contact with the plant can also lead to general skin irritation or contact dermatitis.

Invasive species
Epipremnum aureum can become a highly invasive species when introduced into tropical countries where it is not native. In Sri Lanka, it overgrows several hectares of the Udawatta Kele Sanctuary in Kandy. Having no natural enemies, it completely overgrows the forest floor as well as the trunks of trees, causing severe ecological disruption.

It has also invaded the Kurulukele Forest Reserve in Kegalla, Sri Lanka, and other places where it has been planted as a decorative plant, or to hold steep banks along roads. It was included in the Florida Exotic Pest Control Council's 1999 list of invasive species.

A study published in the South African Journal of Botany found the species to be a potential risk of becoming an invasive species along the coasts of South Africa. It suggested a number of different ways to prevent the spreading of the species in the wild, one of which included barring the cultivation of the species outside of an unsupervised area. Additionally, however, the study pointed out that E. aureum cannot propagate on a large scale due to its lack of seed banks as well as its minimal immunity to herbicides. If the plant is maintained in a controlled area, it is not as significant a threat as when it grows freely in the wild.