Water bamboo (Jiāo bái, wild rice, Zizania aquatica L.)
Summer is the season for water bamboo (Zizania stems). Mother used to buy them from the market and stir-fry them with shallot. I did not know the difference between them and bamboo shoots (竹筍， zhú sǔn) back then — water bamboo (茭白筍，jiāo bái sǔn, Zizania stems) is the result of gall formation of the plant infected by the smut fungus Ustilage esculenta L. Mom always call it “ kha-pe̍h-sún” in Taiwanese, making it sounds like “white foot bamboo shoots”. I never question its name except one particular summer. That summer there are a lot of Zizania stems with black spots inside (灰茭， huī jiāo), so I asked Mom “Should this be called ‘kha-oo-sún’?” in mischief.
Zizania aquatica L. (wild rice, Canadian rice) was called “ gū” (菰) in ancient China. Although we eat their stems in Taiwan nowadays, Chinese people used to eat the ‘wild rice’ produced by them, just like people living in North America and India. It should be noted that Zizania does not belong to Oryza genus — although both of them belong to grass family, Poaceae. However, there are several species of wild rice being cultivated in North American and India. In order to avoid confusions, I shall use “gū” to describe Z. aquatica L. when I talk about wild rice produced in China/Taiwan or just simply the plant, “water bamboo” when I talk about the enlarged stems of them, and “wild rice” when I talk about wild rice produced elsewhere.
The cultivation of “gū” in China can be traced back at least for 1,000 years. The poet and writer Sima Xiangru in Han Dynasty (司馬相如, 179 BC- 117 BC) mentioned it in his “Fu on Sir Vacuous” (子虛賦，Zixu fu ) [1]and The Rites of Zhou （周禮，300 BC- 100 BC）suggests that “gū” is best eaten with fish[2], further demonstrates that ancient Chinese people started consuming “gū” at least for 2,000 years. Chinese scientist and physican Li Shizhen (李時珍, 1518-1593) thought the reason why “gū” is also called “ diāo hú”(雕胡) is probably a mistake, since “gū” will be senescent (diāo, 凋) after frost and people usually collect its grains at that time[3].
Since “gū” is a common grass around shallow water in lakes and slow-flowing streams, it is often mentioned in ancient Chinese poems. However, water bamboo is neither bamboo nor the sprout from “gū” — it’s the fungus gall resulted from infection. The smut fungus Ustilage esculenta L. produces auxin and cytokinin which stimulate cell division of the stem. The infection also prevents the plant from reproducing sexually, therefore the importation of water bamboo is prohibited in North America[4]. In China and Taiwan, water bamboo is propagated asexually to preserve the fungus.
“Gū” was regarded as a precious crop in ancient China. It was said that the porridge of “gū” is very delicious and fragrant. “Gū” was probably one of the “nine important grains” (九穀) way back then. The book Huainanzi (淮南子 ，206 BC- 9BC) even use “gū” as a metaphor to describe when people was preoccupied, he cannot enjoy his favorite music, sleep terribly even with best mattress and pillow, does not have good appetite even with porridge of “gū” with beef is served [5].
Li Shizhen was probably the fist person to recognize the present of “germs” inside water bamboo. In his book, Compendium of Materia Medica (本草綱目）, he mentioned that “there’s germs inside to make it look like squash”[6]. However, he did not pursuit it further. Paul C. Hennings (1841–1908) discovered the smut fungus in 1895 but he mistakenly concluded that the fungus infects the plants’ inflorescence. It wasn’t until 1951 that L. Roger discovered that infected Zizania will not bolt and suggest that it was the stem infected[7].
Because “gū” was not actually a domesticated crop, it is difficult to harvest its grains — its grains ripen at different time, so farmers will have to collect it day after day. During Tang (唐)and Song(宋) Dynasty, the increase of population forced the change of land use, making more people use riverside and lakeside as fields for growing crops like rice and wheat, so there’s less and less land for Zizania. The advancement of agricultural techniques allowed people being capable of cultivating water bamboo asexually, too. Therefore, the purpose of growing Zizania gradually changed from gathering grains to harvesting water bamboo. Farmers even pluck out those plants that do not “growing” water bamboos and call them “male”(However, Zizania is hermaphrodites so there is no “male” or “female”.). As a result, the polymath Su Song (蘇頌，1020-1101) regarded Zizania as vegetable (water bamboo) only, stressing “gū” as “too cold and not suitable for general public use”[8].
There’s a higher chance of “male” water bamboo to appear when the ambient temperature is 30 degrees Celsius above with less sun and more nitrogen fertilizer supplements[9]. Farmers in Taiwan also discover that too much pesticides will increase the appearance of “male” water bamboo. Although these plants should be able to set seeds, they are usually sterile due to defect in meiosis. In 2018, a farmer from Fong-Lin county discovered some wild Zizania population in a deserted pond and started to cultivate them [10]. Perhaps one day we can taste the delicious “gū” as the poet Li Bai (李白，701-762) described in his poems. If Zizania is left in the field for too long, the fungus inside plants will ripe and produce spores, which is called 灰茭( huī jiāo, gray water bamboo) in Taiwan.
Maize (Zea mays) can be infected by a different strains of smut fungus ( Ustilago maydis) too. The infection of maize smut fungus will also result in fungus gall formation of its ears. Mexicans call it “huitlacoche” and harvest them before spore formation. I recently found some of them in Taiwan, too. I ate it out of curiosity and I have to say it is not more delicious than uninfected maize.
With the advancement of agriculture, farmers in Taiwan nowadays can grow them all year round. They discovered that nighttime illumination will inhibit the growing of water bamboo in 2008[11], it has been used as a way to regulate the production of water bamboo ever since. However, importation of water bamboo in US, Canada and Europe is not allowed and will probably never be allowed due to concerns for not being able to harvest wild rice, just like the maize smut fungus gall is considered to be abnormal and must be eradicated in Taiwan. If you happened to visit Taiwan, water bamboo is something you shouldn’t miss. You can eat them stir-fried, baked or just mix them with various vegetables in a vegetable stew. Its very sweet and crisp — absolutely good stuff to try!
References:
[1] 《子虛賦》：「其卑溼則生藏莨蒹葭，東薔雕胡，蓮藕菰蘆，蔄軒芋，眾物居之，不可勝圖。」
[2] 《周禮‧天官冢宰》:「魚宜菰」
[3] 李時珍《本草綱目‧穀之二》：「菰本作 ，茭草也。其中生菌如瓜形，可食，故謂之 。其米須霜雕時采之，故謂之凋 。或訛為雕胡。」
[4] Watson, T., et al. (1991). Disease Note: Smut of Manchurian wild rice caused by Ustilago esculenta in California. Plant Dis. 75 1075.
[5] 《 淮南子‧詮言訓》：「心有憂者，筐床衽席，弗能安也；菰飯犓牛，弗能甘也；琴瑟鳴竽，弗能樂也。患解憂除，然後食甘寢甯，居安遊樂。」
[6] 李時珍《本草綱目‧穀之二》：「菰本作苽 ，茭草也。其中生菌如瓜形，可食，故謂之 。其米須霜雕時采之，故謂之凋 。或訛為雕胡。」
[7] L. B. Thrower and Yuk-Sim Chan. 1980. Gau Sun: A Cultivated Host-Parasite Combination from China. Economic Botany, Vol. 34, №1 (Jan. — Mar., 1980), pp. 20–26
[8]《蘇頌‧本草圖經》：「 皆極冷，不可過食，甚不益人。惟服金石人相宜耳。」
[9] 蔡正宏。茭白與黑穗菌的相互關係。台中區農業改良場一○一年專題討論專集。
[10]2018/3/7。〈北部〉種罕見菰米 農民盼重現雕胡飯。自由時報。
[11] 行政院農業委員會。光照美人腿的革命事件； 2008/12/7。【一步一腳印】化危機為轉機 埔里美人腿革命。TVBS。
