Psidium cattleyanum

Appearance

''Psidium cattleyanum'' is a small, highly-branched tree that reaches a maximum height of 13 meters, although most individuals are between 2 and 4 m. ''P. cattleyanum'' has smooth, grey to reddish-brown bark, with oval to elliptical leaves that grow to 4.5 cm in length. It bears fruit when the plants are between 3 and 6 years old. This fruit has thin skin that ranges from yellow to a dark red or purple, is ovular in shape, and grows to around 4 cm in length. Its flowers grow either individually or in clusters of three, and each flower has five petals.

''P. cattleyanum'' reproduces through setting seed and through cloning. Clonally produced suckers tend to have a greater leaf area. Though native to Brazil, it is now distributed throughout many tropical regions. It was introduced in Hawaii as early as 1825 to create an agricultural market for its fruits, but it has yet to be a commercially viable product. It is now highly prevalent in tropical rain forest ecosystems due mainly to accidental transportation and its invasive plant properties.

''P. cattleyanum'' has modest economic impacts in Hawaii due to its edible fruits. However, products made from ''P. cattleyanum'' are not commercially available because of a lack of market and the heavy presence of fruit flies. This renders the fruits inedible soon after they are picked. It’s seeds have many health benefits, including antioxidant, anti-inflammatory, and antimicrobial properties in addition to a high amount of vitamin C.

Naming

Native to Brazil where it is known as ''araçá'' and adjacent tropical South America, it is closely related to common guava , and like that species is a widespread, highly invasive species in tropical areas throughout the Indian and Pacific Oceans. It also occupies humid subtropical forests such as in the Azores, though it is not as invasive there. It tends to form dense, monotypic stands which prevent regrowth of native species, and is very difficult to eradicate; it also provides refuge for fruit flies which cause extensive agricultural damage. It is able to propagate quickly due to the spread of its seed, which occurs as its seeds fall and as birds and feral pigs transport fruits, as well as through its root sprouts.

As an invasive species, ''P. cattleyanum'' is sometimes erroneously called Chinese guava. It was introduced to many of the areas it now invades due to human usage as a crop for its edible fruit.

Cattley guava is sporadically naturalised in coastal areas of Queensland and northern New South Wales. It is also naturalised on Lord Howe Island, Norfolk Island and Christmas Island . The yellow variety bears even more heavily than the red and generally has larger fruit.

''P. cattleyanum'' grows effectively in undisturbed areas, complicating restoration efforts in sensitive habitats. Its ubiquity in damaged ecosystems further muddles management due to its high dispersal from these less-sensitive habitats to more fragile habitats.

''P. cattleyanum'' acts as an invasive by creating dense thickets that crowd out sunlight, limiting the potential for other plant species to coexist. Its ability to thrive in a variety of different habitats under many different ecological conditions threatens native flora of many different habitat types. Additionally, its potential allelopathic qualities further complicate the ability of other plant species to coexist.

Guava is also one of the most invasive species on Réunion where it is a threat to the endemic forests.

Habitat

''P. cattleyanum'' occurs primarily in mesic tropical rainforest environments at an elevation of up to 1300m, but is found primarily below 800m. Its native range is restricted to the Amazonian Basin in Brazil, but it has established in many other tropical areas of similar characteristics.

''P. cattleyanum'' does not dominate plant communities in its native range. But, it is invasive due to its robust tolerance to many different environments. ''P. cattleyanum'' is prevalent in both undisturbed and highly disturbed roadside habitats in its invasive range. Its invasive quality may be explained by a high amount of genetic variation, as variants of different fruit colors cluster at different elevations. Additionally, ''P. cattleyanum'' is both very shade-tolerant and able to withstand soils with a moderate to high pH level. It is also capable of withstanding heavy leaf litter and responding to bending or breaking of its branches by generating vigorous shoots.

''P. cattleyanum'' is often associated with invasive feral pigs The two species are often found near each other, most likely because feral pigs aid in the spread of ''P. cattleyanum''. The pigs disturb habitats by digging in the soil, making it easier for ''P. cattleyanum'' seeds to reach the soil. Additionally, feral pigs may ingest the fruits, whose seeds reach the soil in the scat of the feral pigs.

Preliminary research suggests that ''P. cattleyanum'' is allelopathic, as its roots have been found to inhibit the growth of at least two other plant species when soil pH was not a factor.

Uses

The whole fruit can be eaten as both the thin skin and juicy interior are soft and tasty. It can also be used to make jam. The skin is often removed for a sweeter flavour. The seeds are small and white in colour. Its leaves may be brewed for tea. The wood of the tree is hard, compact, durable, and resistant, and is used for lathe work, tool handles, charcoal, and firewood. The plant is indispensable for mixed planting in reforestation of reclaimed and protected areas in Brazil.

Necklaces are reported to be handcrafted in Tanzania by tying together beads made of individual fruits.