Scientific Name: Ipomoea aquatica Forssk.
Local Name: Taiwan Gazun
Common names: Kang kong, Pak boong
|Soil Preference||Well-drained loamy or semi-clay||Well-drained loamy or semi-clay||Well-drained loamy or semi-clay|
|Light Preference||Full-sun; partial shade||Full-sun; partial shade||Full-sun|
|Water Preference||Lots of water||Lots of water||Lots of water|
|pH Preference||5.5 – 7.0; prefers fertile soils rich in organic matter|
A close cousin of the highly popular Myanmar lae-gazun (paddy gazun), the Taiwan gazun is a variety of watercress that has adapted to land-based (terrestrial) conditions in high-humidity, tropical environments. The plant is claimed to come from China, where records written by Chinese scholar Lee Shih Chan in the 1590s indicate the popularity of the plant among farmers, replete with instructions on how to store gazun cuttings for future farming seasons. Called ‘Ong Tsoi’ by the Chinese, ‘ong’ refers to the act of burying plant cuttings under the soil and ‘tsoi’ means vegetable.
The Taiwan gazun is a perennial creeper that can grow up to 3 metres and can be continually harvested. After the first harvest its leaves transform from sharp blades into wider forms like that of local gazun varieties. Flowers appear after 2-3 months depending on the conditions; if left to seed a single plant can produce up to 240 seeds.
The vegetable can be grown from cuttings or from seed. Traditionally, farmers grow taiwan gazun in beds using seeds as it ensures the best growth form for sale value. This vegetable can be harvested after 28-32 days and new shoots grow back after 14 days for subsequent harvests.
Fun Fact: The Taiwan gazun is a close relative of the sweet potato (ipomoea batata); both are from the family convulvucaea.
The Taiwan gazun is similar to local varieties of gazun in its structure, with a hollow stem indicating its aquatic ancestry for extracting nutrients from water and clayey soils. It favours high-moisture tropical conditions and thrives when the soil is constantly moist.