About Wasabi (Wasabia japonica)Wasabia japonica (wasabi) are slow growing perennials with a rooted, thickened stem called a rhizome, long petioles and large leaves. All plant parts, including rhizomes, roots, stems and leaves are harvested and valued for various uses.
The wasabi rhizome serves as storage for the plant's nutrients (similar to a potatoe). It is this concentration of energy which produces the strongest pungent flavors so the rhizomes are generally most valued for culinary and health purposes. It's appearance is similar to a brussel sprout stalk after sprouts are removed. The white roots emerging from the bottom of the rhizome can become long.
The leaf bearing stems (petioles) of the Wasabia japonica plant emerge from the rhizome to a length of 12 to 18 inches and can reach a diameter of up to 40 mm (1 ½ in). They terminate into single, heart shaped leaves that, in optimum conditions, can reach the size of a dinner plate. The leaves and leaf stems (petioles) are quite brittle. Breakage or damage from animals, field workers or mishandling can cause growth to slow and even suspend for periods of time.
Using traditional sawa (water-grown) methods, wasabi can take as much as three years before the rhizomes reach market maturity. Initially, given the right conditions, the perennial plant produces robust top and root growth, reaching approximate knee height (2 feet) with an overall width of about the same. After this establishment phase, the rhizome begins to build and store reproductive nutrients. Rhizomes may reach a size of six to eight inches in eighteen to twenty-four months.
Under optimum conditions, Wasabia japonica will reproduce itself by seed. Since it is highly valued, new planting material is also propagated in laboratories via tissue culture techniques. In commercial wasabi farms, plant stock is further extended by replanting small offshoots which, like with strawberry plants, characteristically occur as Wasabia japonoica matures.