Clove: A spice with many uses

Image by Franz Eugen Koehler, Koehler’s Medizinal-Pflanzen (Public domain)

Yesterday was the shortest day of the year in the Northern Hemisphere (also known as the Winter Solstice). At my home in the UK we received less than 8 hours of daylight today before the night closed in again, and the weather at this time of year is generally rather grey and damp. The gloom outside makes December my least favourite time of year, but I must confess that the food, drink and other traditions that accompany this period do help to make up for it.

Lots of the winter/Christmas themed foods eaten in the UK and other European countries are traditionally flavoured with spices. One of my favourite of these spices is the clove. Cloves are the dried flower buds of a medium-sized tree called Syzygium aromaticum, which is native to the ‘Spice Islands’ of Indonesia. It is one of the most valuable spices in the world and has been used for centuries as a flavouring, preservative and in medicinal remedies.

Sex change by fungus

White campion infected with anther smut fungus. Image by Martin C. Fischer (CC BY 4.0)

Fungi reproduce by releasing spores that lie dormant in the environment until conditions are right for them to grow. The spores of fungi that infect plants are often released from fungal structures that develop on the surface of their hosts’ leaves or stems. However, the anther smut fungus (Micobrotryum lychnidis-dioicae) employs a more unusual strategy. Its spores are displayed on its host’s flowers so that they can be carried to other plants by insect pollinators.

Anther smut fungus can infect a small flowering plant called white campion (Silene latifolia). White campion is dioecious, meaning that each plant can only produce either male or female flowers. In the flowers of the male plants, pollen is produced by structures called stamens. When the fungus infects a male plant, it manipulates the plant so that the stamens no longer produce pollen and display fungal spores instead.

The helpful onion

Field of onions in Ismaning, Germany. Image by Rainer Haessner (CC BY SA 3.0 via Wikimedia Commons)

This month it was all change in my vegetable patch as I harvested the last of the crops I planted in the spring and planted new things to grow over the winter. On a bit of whim I decided to plant some onion sets (mini bulbs) at one end of the patch, which should be ready to eat in early summer next year.

Onion is one of the oldest known cultivated plants and the earliest archaeological evidence of onions in human settlements dates back to around 5000 BC (Bronze age). It is grown all over the world where it features as a staple vegetable in a variety of dishes. It is not clear where they originated from, but there is some evidence that they may have come from southwestern Asia. Most cultivated onions are varieties of the common onion (Allium cepa L.) but some other onion species are cultivated too.

Producing the perfect tomato

Image by regan76 via Flickr (CC BY 2.0)

This summer, I’ve been growing some vegetables in my garden. As a novice gardener, I selected some plants to grow on the basis of what is “easy to grow” rather than any other concern. Fortunately for me, one of my favourite foods happens to be the tomato, and tomato plants (Solanum lycopersicum) are very easy to grow even in small gardens like mine.

For culinary purposes, we generally treat the tomato as a vegetable, but it is in fact a fruit. The tomato plant comes from the Andes in South America where it grows as a vine (1). It is not certain when the plant was first cultivated but it was already being grown in Southern Mexico by 500 BC. At this time, the fruits were about the same size as cherry tomatoes and likely to be yellow in colour.

The (un)natural history of maize

Image by Spiritia licensed under CC BY-SA 3.0 via Wikimedia Commons

As a PhD student, I once scared some work colleagues by making popcorn during a tea break (in the kitchen, not the lab, I hasten to add). They did not expect to hear the microwave making a series of “popping” noises, and for a few moments, I think they were genuinely worried that the microwave might explode.

Popcorn is made from heating the grains (kernels) of the plant maize until they explode, or “pop”. Also known by its latin name Zea mays ssp. mays, maize is the second most important crop plant in the world behind rice and is widely used in many human foods, as well as for animal feed and to make biofuels. It has many characteristics that make it useful to humans. Maize produces large kernels with high starch content (except for the varieties that are grown to make sweetcorn). The case surrounding a kernel is firm, but soft enough to allow us to grind these kernels to make cornflour. Also, harvesting the crop is relatively easy because the kernels stay on the cob even when ripe.

The precious pods of the vanilla orchid

By H. Zell licensed under CC BY-SA 3.0 via Wikimedia Commons.

At the mention of “vanilla”, the first things I think of are ice cream, cake and other tasty foods. Next, I think of the little bottles of vanilla extract or flavouring that I often use when baking. In turn, that makes me think of the brown, shrivelled vanilla pods I have occasionally used in particular recipes. Vanilla is a popular ingredient in many foods and perfumes, but where does it come from?

The answer lies in an orchid called Vanilla planifola (also known as flat-leaved vanilla), which originates from Mexico. The Totonac people of Mexico were the first to cultivate vanilla. In their mythology, this plant was born when Princess Xanat—whose father had forbidden her from marrying a mortal—fled to the forest with her human lover. The lovers were captured and killed, and it is said that the vine of the first vanilla plant grew from the ground where their blood landed (2).

The surprise potatoes

One of the potato plants I found in my garden. Two shoots and plenty of roots are growing from the tuber. Growing from the stems are several long white structures called stolens from which new tubers will grow later in the year.

A few weeks ago, I found some potato plants growing in the garden of my new home. The plants were completely surrounded by weeds but—after I nearly stabbed one with a garden fork—I realized what they must be when I noticed that the stems were growing from buried potatoes. Apparently, the previous occupants missed some of their crop when they harvested their potatoes last year.

Potato (Solanum tuberosum) is the world’s fourth most important food crop (behind rice, maize and wheat) and is grown across the globe in areas with temperate and sub-tropical climates. It belongs to the nightshade family of flowering plants, which also includes other crop species such as tomato, aubergine (also called eggplant) and chilli pepper (1).

Guest post. The private life of a common garden weed

By Guru V Radhakrishnan (@guru_vighnesh)

Marchantia polymorpha subsp. ruderalis growing in Brandenberg, Germany. Splash cups are visible on some of the thalli. Image by Franz Mattuschka (CC BY-SA3.0) via Wikimedia Commons

The umbrella liverwort (Marchantia polymorpha) is a noxious weed. It grows in most gardens, paths and glasshouses, and is found in almost all parts of the world – from tropical to arctic climates. There are several subspecies of this plant that are found in damp habitats at varying altitudes. The plants themselves are of little economic importance, but in ancient times, liverworts were believed to be a cure for liver diseases. This ancient idea was part of the “doctrine of signatures” [1]. This doctrine suggested that plants resembling a certain body part could be used to treat ailments of that body part. Although an interesting idea, there is no scientific evidence to support this claim.

The genus name Marchantia comes from the name of a French botanist Nicholas Marchant. And the species name polymorpha is Greek for many forms (polymorph). This name comes from the ability of these plants to take up different sizes, shapes and shades of green depending on the conditions they are grown in.

Treating heart disease with foxgloves

Common foxglove flowers. The scientific name Digitalis means “finger-like”. Image by H. Zell (CC BY-SA 3.0) via Wikimedia Commons.

The common foxglove (Digitalis purpurea) is a pretty flower native to Western Europe. It is commonly found in open spaces especially in recently cleared woodland and other places where the ground has been disturbed, but is also popular in gardens as an ornamental plant (1). Although the plant is poisonous to eat, it has been used in traditional medicines for centuries, but it wasn’t until the 18^th century that its medicinal benefits were thoroughly examined by a British doctor called William Withering (2).

Dropsy (now known as oedema) is the build up of fluid in the body. In the 18^th century the condition was often fatal as patients could “drown” in the fluid that built up in their lungs. Dropsy can be caused by heart failure because the decreased flow of blood around the body leads to the kidneys retaining more fluid.

The next threat to ash trees in Europe

The European Ash (Fraxinus excelsior) is the Organism of the Month.

European ash in Burgwald, Germany. Image by Willow (CC BY-SA 2.5)

As you may know, Europe’s ash trees are at war with a fungus that causes the disease ash dieback. But even as the European ash (Fraxinus excelsior) fights this enemy, there is another threat that is already decimating ash trees in North America – the emerald ash borer beetle.

This pretty little insect – also known as Agrilus planipennis – is native to eastern Asia including China, Japan and the far East of Russia. The beetle lays its eggs on ash trees and the grubs burrow between the bark and the wood. This can destroy the phloem vessels and in severe cases kill the tree (1).

In 2002, the beetle was discovered in ash trees in Michigan, USA, and since then has been spreading across the US and into Canada (2). The beetle probably arrived in the US several years before it was first spotted and is said to have reached the continent in a shipment of Japanese car parts (1).