Sagittaria trifolia is a herbaceous, perennial aquatic plant belonging to the family Alismataceae, also known as water-plantains. In Malaysia, it is called “Keladi Cabang” in Malay and “Arrowhead” in English (Ong, 2006; Flach & Rumawas, 1996). This widespread species occurs from south European Russia to Japan, Malaysia and several provinces in China. It is commonly found in rice paddy fields, ponds, lakes, marshes and channels (Zhuang, 2011).

This species has distinctive arrow-shaped leaves, which give it the common name arrowhead. Each leaf has a pointed tip (apex), two long side lobes that stick out like wings and a shorter middle part between the lobes. The leaves grow above water when they mature and have a sheath that wraps around the base of the stem.

This plant can grow up to 1 m tall. It spreads by producing stolons, which are underground stems. At the end of some stolons, the plant forms small tubers, which are round, starchy roots that store food. These tubers resemble mini potatoes and are edible in some cultures (Tropical Plants Database, 2024).

There are two main recognised subspecies of Sagittaria trifolia, which differ mainly in tuber size and use. The wild form is S. t. subsp. trifolia with smaller tubers and is not commonly harvested for food, but plays an important ecological role. Whereas the cultivated S. t. subsp. leucopetala with larger, starchy tubers is extensively grown in China and other Asian countries as a food crop (Flora of China Editorial Committee, n.d.).

The flowers of S. trifolia grow in rings or whorls of three along a tall stem, arranged in multiple layers. The lower rings usually bear female flowers, while the upper ones carry male flowers. The male flowers grow on thin stalks measuring about 0.5−1.5 cm long, while the female flowers grow on shorter stalks. Each flower has three small green sepals. These sepals are little protective covers that wrap around the flower bud before it blooms. Once the flower opens, the sepals are still visible underneath the petals. The flower has three large white petals that are about twice the size of the sepals. The male flowers have many stamens with yellow anthers, which produce pollen. These delicate, white flowers are often seen standing above the water's surface and are quite eye-catching during the blooming season. After pollination, female flowers produce dry fruits called achenes. Each achene is about the size of a sesame seed, with a small wing and a tiny beak-like tip at the top.

The plant’s flowering and fruiting season varies across regions. In Malaysia, there is no specific data on its fruiting, but it is known to flower all year long in the tropical climate (den Hartog, 1957). In China, it typically lasts from May to November (Flora of China Editorial Committee, n.d.), whereas in India, it occurs in March and April (eflora of India, 2007). In the UK and US, the plant usually flowers between July and August (Plants for a Future, n.d.). These differences in timing are largely due to the varying climates and growing conditions, where tropical environments support year-round growth, while temperate regions have more seasonal blooming periods.

Functionally, the plant provides shelter and food for small aquatic animals and insects. Also, it helps stabilise wetland ecosystems and filter pollutants from water. Although this species is not commonly consumed in Malaysia, its edible tubers are used in Chinese and Japanese cuisine. Medicinally, the plant is known to have antiscorbutic properties that help prevent scurvy, a type of disease caused by a lack of vitamin C. It also acts as a diuretic to help the body eliminate excess water and salt. The leaves are used to treat skin problems, and the tubers are sometimes used to induce premature birth in some cases (Duke & Ayensu, 1985; Tropical Plants Database, 2024; Zhuang, 2011).

Although this arrowhead is valued in some regions for its edible tubers and ecological role, it can also become a problematic weed, especially in rice paddies. It grows quickly and spreads easily, competing with rice plants for sunlight, nutrients and growing space. Once established, it can be difficult to manage, potentially lowering rice yields and increasing the effort and cost for farmers to control it. Additionally, decomposing leaves can release harmful substances into the soil, potentially causing pollution and compromising soil health (Guo et al., 2025). In some areas, chemical herbicides are used to control plant growth, which may raise environmental concerns (Jeon & Kim, 2017). Because it is widespread and occurs frequently throughout its range, no major threats have been identified. As a result, it is classified as Least Concern on the IUCN Red List (Zhuang, 2011).