Hishi Mochi (red, white, and green lozenge-shaped rice cakes) (菱餅)
Hishi mochi is a kind of Japanese confectionery. It is displayed with dolls for the Doll Festival, also known as Girl's Day, on March 3.
It generally has three layers of red, white, and green but in some regions, colors such as yellow are added to give five or seven colors with the mochi cut into squares and layered. The current shape dates from the Edo period.
The red rice cake represents peach blossoms for respecting ancestors, exorcising disasters and for celebrating health by getting its color from cape jasmine, which has detoxifying properties. The white rice cake includes water caltrop (trapa japonica) seeds, is effective in decreasing blood pressure, and represents cleansing and lingering snow. The green mochi, known as kusa mochi, originally got its color from gnaphalium affine (cottonweed), whose Japanese name means 'mother and child plant,' but since this pounding a mother and her child, it was changed to mugwort, which is effective in increasing blood circulation. New mugwort sprouts remove impurities and representing sprouting green grass.
There are theories that hishi mochi was originally the hishi-hanabira mochi (lozenged-shaped flower petal mochi) eaten in the imperial court at New Year's, and that the original triangle shape was changed to a lozenge shape to pray for fertility and family prosperity because the seeds of the water caltrop (which is written in Japanese with the same character as lozenge) are highly fertile and for longevity based on the story of a hermit who lived for a thousand years by eating the seeds. The lozenge shape is said to have been modeled on the female genitalia.
There is another theory that it was a custom of the Ashikaga clan in the Muromachi period to eat red and white lozenge-shaped rice cakes during the New Year's holidays, and when these were introduced to the imperial court, a layer of kusa mochi was added, giving rise to hishi mochi.
There is a triangular sankaku mochi in parts of Shizuoka Prefecture.