Aroids: The fascinating world of plants with strange flowers

Have you ever come across a plant with an inflorescence that looks like a giant green or white tongue sticking out of a pot? Or a plant with spiky, alien-like flowers that emit an unpleasant odour? If you have, chances are you have encountered an aroid.

Aroids are a family of flowering plants that includes over 4,000 species, with many of them grown as houseplants. They are known for their large, showy leaves, unique inflorescences, and in some cases, their pungent scent. Let's take a closer look at what makes aroids so fascinating.

What are aroids?

Aroids are members of the Araceae family, which is distributed across the tropics and subtropics. They can be found in a range of habitats, from rainforests to deserts. Aroids are known for their large, often ornamental leaves, which come in a variety of shapes and sizes. 

Some aroid leaves are heart-shaped, like those of the popular houseplant philodendron. Others are arrow-shaped, like those of the elephant ear plant. In Bangla, certain groups of aroids are called "kachu". 

But what sets aroids apart from other plants are their inflorescences, or flower clusters. Aroids produce inflorescences that are unlike any other in the plant world. Some aroids, like the peace lily, produce a spadix, which is a fleshy spike covered in tiny flowers. The spadix is often surrounded by a modified leaf called a spathe, which can be white, green, or a range of other colours.

Other aroids produce more bizarre inflorescences. The corpse flower, for example, produces a spadix that emits a foul odour evocative of rotting flesh. The voodoo lily produces a spadix that is wrapped in a frilly, skirt-like spathe and emits a smell that has been compared to spoiled meat.

Why are aroids so popular?

Aroids have become incredibly popular houseplants in recent years, and it's easy to see why. For one thing, aroids are relatively easy to care for. Many aroids are tolerant of low light conditions, and they do not need to be watered frequently. Some aroids are even known for their ability to purify the air.

But aroids are particularly popular because of their striking appearance. With their large, showy leaves and unique inflorescences, aroids make a statement in any room. They are also incredibly diverse, with species that range from tiny, delicate plants to massive trees. This means that there is an aroid for every taste and every space.

One of the most well-known and widely cultivated aroids is the peace lily (Spathiphyllum spp.), which is prized for its attractive foliage and striking white flowers. These plants are native to tropical regions of the Americas and have become popular houseplants due to their ease of care and ability to thrive in low-light conditions. In addition to their aesthetic appeal, peace lilies are also known for their air-purifying properties, making them a popular choice for indoor environments.

Another popular aroid is the pothos (Epipremnum aureum), also known as devil's ivy. Native to the Solomon Islands in the Pacific, pothos have become ubiquitous as houseplants due to their low-maintenance requirements and trailing growth habit, which makes them ideal for hanging baskets. Pothos are known for their ability to tolerate a wide range of growing conditions, from low light to bright indirect light, and are also known for their air-purifying properties.

One of the most unusual aroids is the corpse flower (Amorphophallus titanum), which is native to the rainforests of Sumatra and is known for its enormous size and foul odour. The corpse flower can reach heights of up to 10 feet and its flower can grow up to 3 feet in diameter, making it one of the largest flowers in the world. The flower emits a smell similar to rotting flesh, which helps to attract its pollinators: carrion beetles and flesh flies. Despite its unpleasant odour, the corpse flower has become a popular attraction in botanical gardens around the world, drawing large crowds of visitors when it blooms, which can take up to a decade to happen.

Aroids in the wild

While aroids are popular houseplants, they are also an important part of many ecosystems in the wild. Aroids provide food and habitat for a range of animals, including birds, insects, and even primates. 

Many species of aroids, being rich in starch, are venerated as food for centuries. Aroids from the genera Colocasia (Kachu) and  Amorphophallus paeoniifolius (Ol kachu) are cultivated for roots. Alocasia macrorrhizos (Mankachu) are eaten for leaves and stalks. Kachu curries hold a special place in Bengali cuisine. However, like all aroids, edible kachu contains calcium crystals called raphides. Raphides, if ingested raw or improperly cooked, can cause throat irritation. Giant aroids are also important in preventing erosion and stabilising soil in wetland habitats.

Aroids in the wilderness of Bangladesh have not been sufficiently studied. In recent years, the Department of Botany at the University of Dhaka and the Bangladesh National Herbarium have reported several aroids undescribed in science or previously unknown to Bangladesh.

In addition, aroids have cultural significance in many parts of the world. In some parts of Southeast Asia, for example, the taro plant is used in traditional ceremonies and is believed to have spiritual significance. And in many cultures, aroids are used in traditional medicine to treat a variety of ailments from arthritis to heart disease. 

Conservation of aroids

Despite their importance in ecosystems and cultures around the world, many species of aroids are threatened by habitat loss, over-collection, and other factors. Over 300 species of aroids are listed as threatened by the International Union for Conservation of Nature (IUCN).

Conservation efforts are underway to protect these important plants. The IUCN is working to assess the conservation status of aroids and identify priority species for conservation action. In addition, organisations like the Global Aroid Conservation Group are working to promote the conservation of aroids through research, education, and outreach.

Aroids also have a darker history. Some species, like the dumb cane plant, are poisonous and can cause severe swelling and pain if ingested. The dumb cane (Dieffenbachia) has spread via humans as avenue and garden plants. Now, it is one of the most invasive plants in the world, disrupting local ecosystems.

Aroids are a fascinating group of plants with a long history of use in food, medicine, and culture. With their unique inflorescences and striking appearance, aroids have become popular houseplants in recent years, but are also an important part of many ecosystems and are threatened by habitat loss and over-collection. By learning more about aroids and supporting conservation efforts, we can help to protect these fascinating plants for generations to come.