Water chestnut is a common aquatic ingredient in the south. Every part of it is valuable. The fruit of the water chestnut is a popular food ingredient, while its rhizome has good medicinal value and is also known as water chestnut stem.
1. Water Chestnut
It is an annual aquatic herb. The leaves are of two types: floating leaves are clustered at the top of the stem, forming a lotus seat-like structure; leaf stalks are 5-10cm long, with a sponge-like air sac about 1cm wide in the middle, covered with soft hairs.
The leaves are triangular, about 2-4cm long and wide, with coarse serrations on the upper half of the edges, and entire margins near the base. The upper surface is green and hairless, while the lower surface has hairs on the veins. The submerged leaves are feathery and finely divided.
The flowers are hermaphroditic, white in color, and solitary in the leaf axils. The calyx is deeply divided into 4 parts, and there are 4 petals, 4 stamens, and a semi-inferior ovary. The style is elongated like a drill, with a head-like stigma, and the flower disk is crested like a rooster's comb.
The nut is triangular and has spines at both ends, with a distance of 3-4cm between the spines. It flowers from June to July and fruits from September to October.
2. Black Water Chestnut
It is similar in appearance to water chestnut, except that the fruit has two angles, is flat, and the tip bends downward, with a width of 4-6cm. It flowers from July to August and fruits from September to October.
3. Crownless Water Chestnut
Also known as hump-angled water chestnut. It is an annual aquatic herb. The stem is slender and flexible, with varying lengths depending on the depth of the water. The leaves are of two types: floating leaves are clustered at the top;
The leaf stalks are slightly thicker, with a diameter of 1.5-2mm, and the floating sacs are larger, with a diameter of 4-6mm. The leaf blades are broadly diamond-shaped or ovate-diamond-shaped, 2-4.5cm long and 2-6cm wide.
The tip is gradually pointed, the base is broadly wedge-shaped or nearly truncate, and the leaf edges have irregular teeth. The upper surface is green, smooth, hairless, and shiny, with indistinct veins. The lower surface is dark green, with prominent main and lateral veins.
The submerged leaves are opposite and pinnately lobed. The flowers are hermaphroditic, white or slightly reddish, with short pedicels, and they grow in the leaf axils. There are 4 sepals, 4 petals, 4 stamens, and a semi-inferior ovary with a single style.
The nut is black, slightly flattened, without a fruit crown, and has two slightly oblique spines on each side, with no spines at the tip. It flowers from July to August and fruits from August to September.
