Botanical identification

Guava is a small evergreen tree with smooth, thin bark and opposite, elliptic leaves. The leaves are especially distinctive for their prominent, closely spaced lateral veins. White flowers are followed by rounded or pear-shaped fruit with green to yellow skin and white, pink or reddish flesh.

The KBE specimen shows opposite simple leaves, short leaf stalks and strongly marked lateral veins. These characters agree closely with Psidium guajava.

Other members of the myrtle family, particularly some Syzygium species, may also have opposite leaves. The guava-like leaf texture and the numerous prominent lateral veins support the identification as P. guajava.

Use in Thai Traditional Medicine

Thai herbal sources document the use of mature leaves and young fruit, particularly in connection with diarrhoeal complaints. The leaves are also recorded in Thai materia medica for oral hygiene and other traditional purposes.

Guava was among the herbs selected for Thailand’s national primary health-care herbal programme, providing documented evidence of its place in modern Thai herbal-health traditions.

Food and cultural use

Guava fruit is eaten fresh, juiced or made into preserves. In Thailand it is commonly eaten fresh, often with chilli, salt or seasoned sugar.

Modern research

Guava leaves contain tannins and numerous phenolic and flavonoid compounds, including quercetin-related compounds. Modern laboratory and clinical research has investigated antibacterial, antioxidant, anti-inflammatory and gastrointestinal effects.

This scientific research is separate from the plant’s historical Thai use and does not constitute treatment advice.

Cultivation

Psidium guajava grows well in tropical climates and full sun. It can be propagated from seed or vegetatively and responds well to pruning.

Safety

The ripe fruit is a familiar food. Traditional medicinal preparations made from leaves or other plant parts should not be treated as equivalent to eating the fruit. Research involving concentrated extracts or medicinal use remains separate from ordinary food use.