tropical plants

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Botany in Popular Culture: The Tan Hua Flowers in Crazy Rich Asians

When a flower blooms, a celebration is in order. Flowers abound for much of the year, which means parties are called for pretty much non-stop (something Andrew W.K. would surely endorse). Since we can’t possibly celebrate every bloom, there are certain plants we have decided to pay more attention to – plants whose flowers aren’t so prolific, predictable, or long-lived; or plants whose flowers come infrequently or at odd times of the day (or night).

This is the case with the flowers of the night blooming cactus, Epiphyllum oxypetalum, which goes by many names including Dutchman’s pipe cactus, queen of the night, orchid cactus, night blooming cereus, and tan hua. Tan hua is the Chinese name for the plant, and this is how it is referred to in the book, Crazy Rich Asians by Kevin Kwan.

In the book, Nick Young brings his American girlfriend, Rachel Chu, to meet his ridiculously wealthy family in Singapore. Before the trip, Rachel was in the dark about the Young’s wealth. She first meets the family and their gargantuan mansion when Nick’s grandma, seeing that her tan hua flowers are about to bloom, throws an impromptu (and lavish) party. Nick refers to the flowers as “very rare,” blooming “extremely infrequently,” and “quite something to witness.”

In a seperate conversation, Nick’s cousin, Astrid, tries to convince her husband to attend the party by claiming, “it’s awfully good luck to see the flowers bloom.” Later, another one of Nick’s cousins tells Rachel, “it’s considered to be very auspicious to witness tan huas blooming.”

Tan hua (Epiphyllum oxypetalum) via wikimedia commons

Native to Mexico and Guatemala, E. oxypetalum was first brought to China in the 1600’s. Its beauty and intrigue along with its relative ease of cultivation helped it become popular and widespread across Asia and other parts of the world. Watching it bloom is considered a sacred experience by many, including in India, where it is said to bring luck and prosperity to households who are fortunate enough to see theirs bloom.

Epiphyllums are epiphytic, meaning they grow non-parasitically on the surfaces of other plants, such as in the crevices of bark or the crotches of branches. Like other cacti, they are essentially leafless, but their stems are broad, flat, and leaf-like in appearance. Showy, fragrant flowers are born along the margins of stems. The flowers of tan hua, as described in Crazy Rich Asians, appear as “pale reddish petals curled tightly like delicate fingers grasping a silken white peach.” A report (accompanied by photos) published by Sacred Heart University describes watching tan hua flowers progess from bud formation to full bloom, a process that took more than two weeks.

Tan huas are certainly not rare, as Nick described them. A number of Epiphyllum species and their hybrids are commonly cultivated; there is even an Epiphyllum Trail at San Diego Zoo’s Safari Park. Listed as “least concern” on the IUCN Red List, their popularity as ornamentals is noted but is not seen as affecting wild populations. Night blooming plants, while fascinating, aren’t all that rare either. Such plants have adapted relationships with creatures, like bats and moths, that are active during the night, employing their assistance with pollination. A paper published in Plant Systematics and Evolution describes the floral characteristics of Epiphyllum and similar genera: “The hawkmoth-flower syndrome, consisting of strongly-scented, night-blooming flowers with white or whitish perianths and long slender nectar-containing floral tubes is present in Cereus, Trichocereus, Selenicereus, Discocactus, Epiphyllum, and a number of other cactus genera.”

That being said, the specialness of a short-lived, infrequent, night blooming flower should not be understated, and really, parties being thrown in honor of any plant are something I can certainly get behind. Sitting in the courtyard late at night, the Young family and their guests watched as “the tightly rolled petals of the tan huas unfurled like a slow-motion movie to reveal a profusion of feathery white petals that kept expanding into an explosive sunburst pattern.” The look of it reminds Astrid of “a swan ruffling its wings, about to take flight.”

Later, “the tan huas began to wilt just as swiftly and mysteriously as they had bloomed, filling the night air with an intoxicating scent as they shriveled into spent lifeless petals.”

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*Thank you Kathy for letting me borrow your Kindle so that I could write this post.

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What Is a Water Chestnut?

This question came up on a recent episode of Every Little Thing, and while I have eaten water chestnuts on numerous occasions, I realized that I have never really considered what they were or where they came from. Thanks to the folks at ELT, I am better informed. So, why not spread the wealth?

Chinese water chestnut (not to be confused with Trapa natans, which is also commonly known as water chestnut) is in the family Cyperaceae – the sedge family. Known botanically as Eleocharis dulcis, it is a member of a sizable genus collectively referred to as the spikerushes or spikesedges. Its distribution is quite expansive, spanning sections of Australia, tropical Africa, several countries in Asia, as well as islands in the Pacific and Indian oceans. It is commonly cultivated in regions outside of its native range, including in North America as a novelty crop.

Eleocharis dulcis is a perennial, aquatic plant that grows in marshes, bogs, and the margins of other wetland and riparian areas in tropical and subtropical climates. Individual plants are clumps of tall, stiff, upright, leafless stems that can grow to over one meter tall. An infloresence is borne at the tops of stems and is a short, cylindrical cluster of small, yellow-brown florets. Clumps of stems are connected via rhizomes, and in this manner dense colonies can be formed. Rhizomes also terminate in corms, which are the edible portion of E. dulcis and the part of the plant that we refer to as water chestnuts.

Chinese water chestnut (Eleocharis dulcis) growing in a bog garden – photo credit: flickr/techieoldfox

Corms are underground storage organs. They are the bases of stems that have become thick and swollen with starch. They are often covered in papery scales – which are the remnants of leaves – that help protect the corm from being damaged or drying out. Buds on the top of the corm form shoots; adventitious roots form on the bottom of the corm. Tubers, which are also modified stems and underground storage organs, differ from corms in that they have growing points at various locations along their surface rather than a single growing point at the top.

Common misconceptions are that water chestnuts are nuts or roots. They are neither. They are corms, or in other words, they are modified stem bases. Apart from that, they are vegetables. Curiously, they are vegetables from a plant family that does not produce much in the way of food for humans. Consider that the next time you eat them. You are eating a sedge.

Corm of Chinese water chestnut (Eleocharis dulcis), the edible portion of the plant – photo credit: flickr/sclereid0309

Chinese water chestnuts can be prepared in many ways, both raw and cooked. I have only had them in stir fries, but they can also be used in salads and soups or ground into flour to make water chestnut cakes. Interestingly, even when they are cooked they remain crisp. This has something to due with the special properties of their cell walls.

As an agricultural crop they are often grown in paddies in rotation with rice. With a few preparations they can also be grown at home alongside your other vegetables. Further information and instruction can be found at various locations online including Permaculture Research Institute, Missouri Botanical Garden, and Plants for a Future.

Having only eaten water chestnuts from a can, I am anxious to try fresh, raw water chestnuts. Apparently they are available at certain Asian markets. When I get my hands on some, I will let you know what I think. Follow me on Twitter or Facebook for further updates.

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What are your favorite ways to eat Chinese water chestnuts? Let us know in the comment section below.

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Ethnobotany: The Henna Tree

A hair dye used in pre-dynastic Egypt is still used today. This enduring plant-based dye has found its way into a great number of cultures going back as long as 6000 years. Its popularity is thanks in part to the broad distribution of the plant itself, but is largely a result of the diverse religious traditions that have incorporated the dye into their rituals. The plant’s use in such traditions continues, while its current popularity extends well beyond that.

Lawsonia inermis is the only species in its genus. It is a member of the plant family, Lythraceae, a family that includes crepe myrtles (Lagerstroemia), cigar plants (Cuphea), and pomegranates (Punica). L. inermis has many common names, including mignonette tree and Egyptian privet. It is most commonly known as, henna, a term that refers to the plant itself, the dye derived from the plant, and the body art made using the dye.

Henna is a shrub or small tree that reaches a height of about 6 meters. The leaves are smooth, elliptically-shaped, and oppositely-arranged on branches that are spine-tipped. Inflorescences are many-branched with numerous small, fragrant flowers. The most prominent features of the flowers are four sepals forming a bowl shape and several white to red stamens reaching towards the sky. The fruits are small, round, brown capsules full of tiny seeds. Henna thrives in dry environments with poor soil; however, it does not tolerate frost. It occurs in tropical and subtropical regions of Africa, western and southern Asia, and northern Australasia. Cultivation by humans has broadened its distribution well beyond its original boundaries.

Lawsonia inermis - photo credit: wikimedia commons

Lawsonia inermis – photo credit: wikimedia commons

Henna has been used to dye the skin, nails, and hair of women and men in many cultures and religions across its area of natural distribution and beyond. Its use has been especially common among women as part of fertility and marriage celebrations. The plant’s dye may have been first discovered around the mouths of browsing livestock – the persistent red-orange color having the appearance of blood. Henna plants are drought-deciduous, but they burst back to life when rain returns, producing abundant new branches, leaves, and flowers. This period of growth coincides with celebrations of marriage and fertility and may explain why it found common use in such traditions.

Dyes are made by crushing dried leaves into a fine powder and then mixing it into a paste using water, lemon juice, tea, or other liquids. A soap or shampoo is produced when henna is mixed with plant extracts containing saponin, and the addition of certain essential oils can enhance the performance of the dye. The compound in the leaves that produces the red-orange dye is called lawsone and is found in varying concentrations depending on the conditions in which the plant was grown. High heat and low soil moisture is said to produce the highest levels of lawsone. More than just a dye, lawsone also has antifungal properties and strongly absorbs UV light, thus its application is beyond cosmetic as it has proven useful against fungal diseases like athlete’s foot and as a sunscreen. And that’s just the beginning.

Henna applied to hair - photo credit: wikimedia commons

Henna applied to hair – photo credit: wikimedia commons

A study published in the Journal of Ethnopharmacology by Semwal, et al. reveals that nearly a hundred phytoconstituents (or “biologically active compounds”) have been isolated from all parts of the henna plant. Henna has long been used medicinally to treat a wide range of ailments, and while it may not be an effective treatment for all that it has been historically used for, it has been found effective for certain things and has great potential for further use.

In the paper, the authors review dozens of studies exploring the many “biological activities” that henna is claimed to have, which include “antifungal, antibacterial, virucidal, antiparasitic, anti-inflammatory, analgesic, and anticancer properties,” etc. Research into these properties is limited and has been “complicated and hampered” by the widespread practice of adding other ingredients (some of them harmful) to henna products. In order for henna’s “therapeutic potential” to be properly explored, the authors advise identifying and standardizing the plant’s active components.

Henna continues to be used in cultures across the world and is particularly prominent in Hinduism and Muslim practices. It is most commonly used to dye hair and create temporary body art (also known as mehndi). Henna art is often applied to the hands and feet, where the skin is thick and absorbs more of the lawsone. It is applied as a paste and either squeezed through a plastic cone or syringe or painted on with a stick or brush. The longer the paste is left on, the darker the stain will be. After a week or so the henna begins to fade as old skin cells slough off.

photo credit: wikimedia commons

photo credit: wikimedia commons

In ancient cultures, henna was thought to ward off the Evil Eye as well as bring good luck and blessings, a trait known as baraka. This belief is part of the reason why henna was incorporated into marriage ceremonies and other religious rituals. Because of henna’s antifungal, analgesic, and anti-inflammatory properties, etc., real benefits are seen when henna is applied to various parts of the body. Semwal, et al. argue that a scientific understanding was not necessary for “recognition of benefit.” Today however, “scientific investigation and quantification of henna’s ‘baraka’ should expand and optimize these traditional qualitative understandings.”

Because of henna’s widespread use and long history, it is not feasible to fit henna’s entire story into a single blog post. Henna is worth exploring on your own. Here are a few more interesting tidbits for now. In Semwal, et al.’s summary there is a mention of henna twigs being “rubbed over the teeth for effective dental self-care” – something to keep in mind in case you find yourself without a toothbrush, and a henna plant happens to be nearby. A paper published in a 1993 issue of Thaiszia – Journal of Botany discusses the historical use of henna in the Balkans. Slavs in the area reportedly treated typhoid fever using a mixture of henna and “the juice of twenty heads of garlic” heated in water. Finally, henna has been used to dye many things, including leather, cloth, and animal fur. Persians have long used henna to dye the manes, tales, and hooves of their horses and other animals. A practice that continues today.

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