Citizens Recording Biodiversity: A Case Study of Epiphyllum

Weina Jin


Everything alive stemmed from just one cell, but under pressure of many factors, differentiated into the great variation of life found on our planet. Biodiversity is a measure of this variation. First zooming in on the story of a mysterious flower, this article relates this plant to approaches to recording biodiversity in both the scientific and public communities and how the data collected may be used.

Introducing Epiphyllum oxypetalum

Figure 1: E. oxypetalum budding (author’s image)

Originating from the tropical rainforests of Central America, the epiphytic, night-blooming cactus Epiphyllum oxypetalum is known by a wealth of vernacular names across the world. Its fame first spread verbally through this maze of names and myth, then physically from rainforest canopies to city balconies.

I first encountered E. oxypetalum on my grandma’s balcony in Beijing – a white flower growing without roots in the soil, indeed similar to how it would look in the rainforest. But there were a few differences – it wasn’t wrapped around a tree to elevate itself in order to get closer to the hard-won light from the sun; rather, it snaked up a wooden stick, basking in plentiful artificial rays from a lightbulb. There was nothing hindering its craving for light or water – and there were also no looming creatures that might regard it as a tasty snack. Our cutting was a gift from a friend – in China, E. oxy is a popular plant and easy to transfer between homes since the surroundings are suitable.

The reason it had been gifted, and received with such excitement, I was soon to find out. I always like to admire flowers, but E. oxy was unique – the bloom ran on a much tighter schedule than the plants I had commonly seen. My grandparents told me it flowers only for a handful of hours, one night every year, and so going to sleep every night was a gamble; even if the bud had not appeared one morning, by the time the next breakfast rolled around the only remnants of the bloom could be the traces of wilted petals in the compost.

Figure 2: E. oxypetalum blooming (author’s image)

We had lucky timing, because soon a handful of buds appeared at the edges of the large leaves. Over the next nights, they became wispier and pinker. Staying up one night, we watched as white jaws exploded outwards. Phone cameras snapped; petals fell. It was over in a matter of hours.

Figure 3: E. oxypetalum on a Beijing balcony (author’s image)

I was interested to know how others had perceived this flower – a Google Search revealed that while it seemed to bring others the same wonder it had brought me, it reached only a niche audience (or so English results suggested).

This wonder had manifested in ‘cactus parties’ in 1930’s America[1], held to celebrate the uncertain, late night bloom, as well as themed zoo trails today[2]. An article from the New York Times even described how a chance encounter led a passerby to watch the bloom in a stranger’s garden[1] (though it is a nice sentimentality to share a sense of magic, please remain cautious when approached by a stranger).

The Naming of Plants

Figure 3: E. oxy’s many vernacular names (author’s image)

When I changed my search terms based on vernacular names obtained from various research papers[3], results increased – the same flower appeared in photos labelled “Queen of the Night”, “Beauty under the Moonlight”, “Gekka Bijin”, “Fleur de lune”, “Yue xia mei ren”, “Kadupul”, “Tan Hua”, “Jin gou lian”, “Flor del baile”, “Galan de noche”, “Wijaya Kusuma”, “Bethlehem lily”, “Quynh Hoa”, “Iruludavare”, among others. Armed with a can of new search terms, many myths and references to religion, the moon and the flower’s physical appearance appeared. (I will refer to the plant as E. oxy from now for simplicity.)

However, as the hits increased, the noise also increased – as a result of our imaginative naming of every plant that blooms at night “queen of the night” or similar, E. oxy is part of an ever-growing collection of flowers bestowed with magical properties simply because they bloom in rare situations.

Tan Hua referring to a brief bloom was a thousand year old idea in China and Japan, though it has not always referred to E. oxy. In the Tang dynasty, it referred to the udumbara, a fig-like tree that encloses the flower within the fruit. As the flower is hidden, a legend sprouted that the flowering was only once every 3000 years. Symbolising reincarnation in Buddhist treatises, in “Utsubo Monogatari” this flower is thought to save those dying from diseases[4]. The reference to E. oxy emerged fairly recently – it was not recognized as a medicinal herb in traditional TCM, but the Lu Chuan Ben Cao (1959) claimed it can act against lung diseases including tuberculosis[5].

Medicinal Uses – Importance and Endangerment of Biodiversity?

Another “Brahma Kamal”, Nelumbo nucifera, the classic lotus, is said to have life-giving properties as a flower that “dropped Amruta, the elixir of life… to place the head of an elephant on the body of Lord Ganesha[6]”. Scientists tend to use “Brahma Kamal” to refer to Saussurea obvallata, used extensively in Tibetan medicine to the extent that its survival is threatened by its heavy extraction from the wild and it is classed as endangered (Semwal considers tissue culture as an alternative)[6].

Many cultures continue to derive medicines directly from plants; E. oxy itself has indeed been used as treatment. Parts of the plant, for example in Malaysia, or Vietnam where the petals are made into soup, are used to treat heart and blood conditions[7]. The “Shoshone Indian tribe calls [E. oxy] “Pain in the heart” and used it for heart pain[7]”. Though not scientifically proven to be medicinally effective, Epiphyllum oxypetalum is widely sold and gifted, particularly in the form of hybrids.

Hybrids – Positive or Negative Influence on Biodiversity?

E. oxy invests a lot into its large flowers, and perhaps expectedly this means it cannot sustain a large volume of blooms, producing only a handful each year.

To discuss hybrids, we will return to one point I mentioned slightly earlier about zoo trails. Zoo trails by nature may seem antithetical for a night-blooming, short duration flowering. Perhaps an offhand event like those cactus parties, yes, but due to hybridisation, even longer duration trails are possible. Collectors are able to produce many types of hybrid with elevated staying power (duration of the bloom), as well as making any modification to appearance (usually larger, more eyecatching flowers).

These epihybrids are bred to introduce and sustain desired traits that seem far removed from their wild counterparts, some new features even reducing fitness, or utility such as lurid colours, antithetical of how they evolved over millions of years to capture night-flying pollinators. These are popularly sold online, as they are still hard to stock due to irregular blooming patterns. The spread of these flowers and the extent of their popularity is unclear, but the hybrids and the original both show no signs of going extinct – they are listed Least Concern on the IUCN Red List.

The Recording of Epiphyllum oxypetalum

I was interested to know about the globalisation of E. oxy. The dichotomy of the pale bloom in the rainforest, and these lurid hybrids decorating visitor walkways – how did luminous petals reflecting moonlight turn to mirrors for artificial bedroom lights half the world away? E. oxy has been naturalised in China, perhaps since a long time ago, as well as some other hotspots around the world[8], but it is not widely known how or when they first arrived.

Limited science is available for this plant. E. oxy has appeared a little in the botanical record on sites like GBIF, which tracks global biodiversity, though it has been the subject of a few papers on chemical analysis[9].

In the case of E. oxy, when it moved to a city balcony, the flower lost something that used to be its raison d’etre. Flitting about to cater to its every whim, humans have replaced the beetles and moths that were the pollinators the plant could not survive without. Though we brought it plentiful light and space, we isolated it from its environment – yet it still blooms, albeit without a motive. A flower flowers to become fertilized and produce fruit, but year after year homegrown varieties of E. oxy are stuck in the prime stage of its life cycle, playing out our imposed mythologies.

Isolating a species, or even a specimen, from its environment is not something new. But in some areas of biology like conservation, especially regarding crucial plant-pollinator relationships, it can be important to consider the surroundings along with a species. That is why it is important to record what biodiversity exists in certain areas, so we can better understand how, whether, and when to protect it.

This is not to say we should not cultivate or hybridise plants, or bring them back from the wild to research or learn more about them. As a widely cultivated garden plant, E. oxy has not really been harmed by this. But there have been more sobering cases – rhino horns targeted due to unfounded myths about its medicinal properties, causing some species to be critically endangered.

Importance of Recording Biodiversity

Wildlife reserves, zoos, botanic gardens and seed banks all keep living records of biodiversity in a denser space than would be found naturally; past biodiversity is recorded in herbaria and museums.

There is also monitoring the current spread of species by making biological records: records that show the location a certain species was observed at a certain date. These can be made as part of research surveys, often carried out in a predefined area with particular species in mind, as well as by the public as part of citizen science. The latter is an area which has recently grown with the rise in use of apps that allow you to identify and submit sightings, powering the ability to contribute with just an internet connection.

Using this data, we can track species richness (the total number of different species), and species abundance (the relative numbers of each species) over a particular area, informing scientists’ or policymakers’ decisions on projects regarding conservation or construction[10][11]. If a rare species is located, for example, it may receive attention, though it is also important to record common species, because trends can quickly change over time[10]. We can also track change in native and non-native species.

We can think of biodiversity at four levels: genetic, species, ecosystem and global. Of these, the ones citizen science is most apt at recording are at the species and ecosystem levels. Collaborating globally allows us to hit the fourth.

How to Contribute to Global Biodiversity Data

One method of tracking plants and animals together with the public has been developed by iNaturalist, a citizen science effort to monitor biodiversity[12]. Due to technological advances, we no longer only rely on pressed specimens from the rainforest, and scientists can also recruit citizen efforts to help them gather data. iNaturalist has set up a good precedent – it is simple in theory to use, and has potential to be a very useful resource. We are also able to understand somewhat the biodiversities of an area without formally sampling it, as sightings can be accessed by location.

However, it is heavily dependent on the user base. As might be imagined, there is significant variation over time and location for quality and quantity of user interaction. Users may be limited also to the species they already recognize, resulting in a map that is not entirely comprehensive, with some sightings of questionable quality being tagged “unknown”.

Other systems for mapping global distributions exist – GBIF only presents data from formally registered institutions[8], while the Map of Life[13] includes collated data from GBIF and other organisations. Some of these sightings are better recorded, but it is still not comprehensive.

As part of my extended project on E. oxy in 2019, I analysed the spread of data on GBIF, which included preserved specimens from Natural History museums and herbaria datasets, in addition to research-grade (reviewed twice with coordinates[12]) records on iNaturalist.

The data showed that this type of distribution recording is not comprehensive; the sightings and records did not include propagations through cuttings in private apartments, for example, and rely for the most part on botanical institutions. 85.7% of all records were of preserved specimens, while E. oxy is usually celebrated socially for its bloom. Its record on MoL largely consisted of the GBIF data as presented, and only shows distribution over parts of the Americas [ref- Map of Life, 2019] – which was not where the majority of the cited scientific research on the phytochemistry of the plant in my project took place. Perhaps this could be due to this species having a lot of vernacular and scientific names, which could bring confusion or complication when recording.

A 2013 paper exploring public engagement in biodiversity research describes the use of “non-traditional sources of data”, including citizen science as an untapped resource, finding “less than 20% of programs collect data published in peer-reviewed scientific articles”. So even if records are made, they might not be used, for data quality reasons (controlling for fickle human attributes like effort, as well as standardisation and verification)[14]. Education is emphasised as a way to improve record collection, as “participation may translate to greater scientific literacy at the individual level, and literate volunteers may collect data for a lifetime”[14].

Another paper describes volunteer recorders’ fascinating behaviour – the phrase “often opportunistic[15]” sums up the findings well. It describes how biases provide “taxonomic, spatial and temporal” uncertainty – it found most volunteers only active for one day. Species abundance and ease of identification correlated positively with recorded sightings. Plant height was also important; spatial compatibility with the subject must not be underestimated. It found that places with water were more popular recording “hotspots”. The paper concluded that such analysis could help integrate volunteer activity with usefulness in projects[15].

Drawing Conclusions on Epiphyllum

Originally found in places such as Mexico, Guatemala, Venezuala and Brazil, E. oxy is readily cultivated in warm temperatures, tropical and subtropical regions. In many places, it has escaped from cultivation and been naturalised, for example in China[3]. Despite a native to the above places in the Americas, the most readily accessible stories and sayings about the plant are of Asian origin, notably in India (where it is endowed some religious significance), China and Japan.

At risk of sounding like a personal statement, my interest in biology was hooked by the myth of E. oxy, a magical plant. One question that presents itself is, if these myths are busted, is the enjoyment eliminated? In February this year, the local Botanic Garden published a few web articles about the first UK flowering of their rarer night-blooming cactus specimen[16]. Yes, there is a rarer specimen (and not just one); a familiar story each time, a white epiphytic cactus flower blooming at night. The articles even described E. oxy as common (I fondly add), although there is no UK data on GBIF for this species.

So what I should say is that my interest in biology was hooked by E. oxy, what I perceived as a magical plant. Did this make E. oxy lose some of its magic for me, now that I knew it was just one of many white-flowering cacti? That an outburst of locals responded to the Botanic Garden’s call for photos by sending in specimens growing at home?[16] I can only shake my head and say something along the lines of, I learnt a lot in the process – some fascinating cultural ideas, some physicochemical facts, and some thought-provoking points, like how the flower “probably dies after flowering because it is not very successful when it comes to self-pollination[17].”

However, “the plant will continue to live and send out new flower shoots[17]”, and attract humans – researchers, cultivators or anyone interested – to view it. It is also important to have such plants at botanic gardens as living records of biodiversity, making plant science studies more accessible than in the field[17].


  1. New York Times. “One Night a Year, This Cactus Flower May Surprise You.” Last modified Sept 15, 2017.
  2. San Diego Zoo. “Epiphyllum.” Last modified 2021.
  3. Lim, T. K. “Epiphyllum oxypetalum,” in Edible Medicinal And Non-Medicinal Plants: Volume 7, Flowers (2014). Canberra: Springer, Dordrecht, 638-640.
  4. Britannica. “Utsubo monogatari.” Last modified 2021.
  5. Yuqun, L.. Traditional Chinese Medicine: Understanding Its Principles and Practices. Beijing: China Intercontinental Press (2017), pp. 8-9.
  6. Semwal, P.. “Brahma Kamal – the spiritually revered, scientifically ignored medicinal plant. (2013)” Current Science, 104(6), pp. 685-687.
  7. R S Upendra, P. K.. “Assessment of nutritive values, phytochemical constituents and biotherapeutic potentials of Epiphyllum oxypetalum (2012).” International Journal of Pharmacy and Pharmaceutical Sciences, 4(5), pp. 421-425.
  8. GBIF. “Epiphyllum oxypetalum Haw.” Last modified 2021.
  9. KR Sunaja Devi, S. L. N. P. M. a. J. G. “Microscopic, pharmacognostic and phytochemical screening of Epiphyllum oxypetalum (dc) haw leaves. (2018)” Journal of Pharmacognosy and Phytochemistry, 7(6), pp. 972-980.
  10. FSC Biodiversity UK. “What is a biological record?” Last modified 2021.
  11. NatureScot. “Why record biodiversity data?” Last modified 2021.
  12. iNaturalist. “iNaturalist.” Last modified 2021.
  13. Map of Life. “Dutchman’s-Pipe Cactus”. Last modified 2021.
  14. Ettinger, Ailene. “Public Engagement in Biodiversity Research (2013).” Last modified Feb, 2013.
  15. Boakes, E., Gliozzo, G., Seymour, V. et al. “Patterns of contribution to citizen science biodiversity projects increase understanding of volunteers’ recording behaviour.” Sci Rep 6, 33051 (2016). Last modified 13 September 2016.
  16. CUBG. “Is my Moonflower the same as your Moonflower?” Last modified Feb 17, 2021.
  17. CUBG. “Secrets of the Moonflower.” Last modified Feb 12, 2021.
  18. Heywood, Vernon. Developing new biodiversity conservation strategies in response to global change (2010). _B_o_ll. M_u_s. Is_t._ B_i_ol. _U_n_iv._ G_en_o_va. 72. 95–122.

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