The Enigmatic Tale of the Hibiscus

Dr. Suresh V., Associate Professor, Government Victoria College, Palakkad

The hibiscus… a hallmark of Malayali nostalgia. Always a frontrunner among ornamental plants. Planting at least one hibiscus in the home garden has been a longstanding practice for Malayalis. Consequently, our very own hibiscus is an indispensable flower in the traditional floral arrangements during Onam. The hibiscus is also the national flower of Malaysia.

For students studying biology, the hibiscus serves as the model for learning floral structure in textbooks. Perhaps for many of us, the scientific name of the hibiscus was among the first we learned.

The hibiscus, widespread across the globe, boasts numerous varieties. Flowers of various colors, sizes, and shapes can be found in different strains. Hibiscus flowers come in a range of colors, including red, yellow, orange, pink, and white. Some varieties have single flowers, while others have double flowers. Due to this immense diversity, the hibiscus holds a prominent place in gardens worldwide.

Beyond being an ornamental plant, the hibiscus also possesses significant medicinal properties. Its flowers, leaves, and roots are used in traditional medicine. Hibiscus helps prevent hair loss and accelerate hair growth. It is also used in skincare. Studies have shown that hibiscus tea is highly beneficial for health.

However, did you know that the hibiscus, which always brings us joy with its smiling red blossoms, harbors a profound secret? That secret is its own lineage. Many have attempted to unravel it, but it has remained an enigma.

Who is it really? Where did it come from?

The hibiscus was first introduced to Europe by Van Rheede through his renowned Hortus Malabaricus Indicus. He unveiled a double-petaled hibiscus.

Botanically, the hibiscus was named Hibiscus rosa-sinensis by Linnaeus, the father of taxonomy. The Latin name is derived from the common name “China Rose.” It was described as “A striking red, double-flowered plant cultivated in India, Sri Lanka, and Indonesia.” Therefore, for a long time, botanists believed that China was its origin. Although it’s called “China Rose,” the hibiscus is not found exclusively in China. It is found in Southeast Asia, Latin America, Africa, and virtually everywhere modern humans live.

Or rather, the hibiscus is found only where modern humans live.

Exactly…

Our hibiscus does not exist in the wild…

The hibiscus does not naturally grow in any forest.

It is not a wild species at all!

Most plants we cultivate have wild relatives. The thousands of crops we see today have been developed over approximately 10,000 years of agriculture, through the selection of plants with the most favorable characteristics. Humans have only recently begun creating hybrids artificially.

However, the case of the hibiscus is different. If the hibiscus doesn’t exist in the wild, where did it come from?

To answer this question, a team of researchers set out to investigate the hibiscus’s ancestry. This team, led by Luca Braglia from the Institute of Agricultural Biology and Biotechnology in Italy, employed DNA-based molecular classification studies. They conducted detailed studies on the similarities and variations among various plants in the hibiscus genus.

In 1769, explorers Joseph Banks and Daniel Solander were on a sea voyage with Captain Cook. In present-day Tahiti, they discovered a very attractive red hibiscus. It had both single and double sets of petals. There, it was called “koute.” For many years, the scientific community believed it was the same as our H. rosa-sinensis. However, recent botanical studies have completely overturned this notion, proving that it is another species with only genetic similarities to the hibiscus. It is now known as Hibiscus kaute.

Another hibiscus relative, with light yellow or light red flowers, was causing a sensation in England. Discovered in British greenhouses in 1863, Hibiscus cooperi originated from Vanuatu, a small island in the southwestern Pacific Ocean. Researchers found its wild relatives in nearby areas.  

The secret of the origin of our H. rosa-sinensis lies here. Our hibiscus is a mixture of the characteristics of these two plants. This hybrid nature is evident in its leaves and flowers. Therefore, our hibiscus is a hybrid of Hibiscus kaute and Hibiscus cooperi.

These two regions are separated by more than 4,000 kilometers of ocean. Natural hybridization between them is impossible. This means that Polynesians must have carried Hibiscus kaute across the Pacific Ocean in canoes (small rowing boats). Brought to the islands of Vanuatu, it was hybridized with Hibiscus cooperi to create our hibiscus.

This is how the hibiscus, which does not exist in the wild, came into being. Genetic studies have confirmed this. That is, the hibiscus, created through hybridization in the southwestern Pacific islands, traveled from there through New Guinea and Indonesia, reaching Europe via Japan, China, and India.

The Hibiscus’s Lineage Journey.

While other hibiscus species produce abundant seeds, fruits and seeds are rare in our hibiscus. Why is this? The secret of the hibiscus’s origin is related to this.

The main reason why natural hybridization does not occur between different plants is genetic. Each plant’s chromosomes and genes have their unique arrangement. Most organisms have two copies of each chromosome. During the formation of gametes in reproduction, cell division occurs through meiosis. This is when chromosomes are equally divided. Homologous chromosomes pair up and separate into two daughter cells during division.

This is called homologous chromosome pairing. If this pairing process does not occur correctly, division will be disrupted. If chromosomes from very different plants come together, this pairing process will not occur properly. Only those that are similar will pair correctly.

Imagine a house with twins who use everything in pairs. What if someone brings only one packet of sweets? Most of the children will tear the packet apart and make a mess.

Chromosomes are similar. If they are not identical, they will tear apart and cause problems. The result is that such a hybrid will not survive.

Therefore, genetic similarity is essential for meiosis to occur. If not, the solution is to duplicate the chromosomes. Organisms with duplicated chromosomes are called polyploids. When all chromosomes are in pairs, pairing and separation occur correctly. This is known as hybridization and chromosome doubling.

Many of our hybrid crops are polyploids, artificially created in crops. This occurs naturally only rarely.

The hibiscus is also a polyploid, a relatively new plant in evolutionary terms. Therefore, its pollination, flowering, and fruiting are still being established. That is why fruits and seeds are rare. Pollinator assistance and favorable climatic conditions also affect it.

It is now clear that Hibiscus rosa-sinensis is not a species but a hybrid of two existing species (H. kaute and Hibiscus cooperi). So, can we conclude the story of the hibiscus?

We can, but there’s a small problem. According to the rules of botanical nomenclature, hybrid plants cannot simply be named Hibiscus rosa-sinensis.

If a plant is scientifically proven to be a hybrid, it needs a mark, a symbol. Hybrid plants are indicated by an “x” symbol in their name.

Therefore, Hibiscus rosa-sinensis will become Hibiscus x rosa-sinensis.

Consequently, textbooks will need to correct Hibiscus rosa-sinensis to Hibiscus x rosa-sinensis.

That’s it…

Now, we can conclude the story of the hibiscus peacefully.

Ref: Braglia, L., Thomson, L. A., Cheek, M., Mabberley, D. J., & Butaud, J. F. (2024). Pacific Species of Hibiscus sect. Lilibiscus (Malvaceae). 4. The Origin of Hibiscus rosa-sinensis: A 300-Year-Old Mystery Solved. Pacific Science, 77(4), 395-415.