Friday, August 16, 2013
To Zing or not to Zing, that is the question
Species name: Zingiber officinale
Common name: ginger
Location: teaching lab at Western
Ginger is one of the most commonly used spices around the world, and one that many, many people love the taste of (you can count me as a non-member of that group; I personally HATE ginger). It is a tropical spice (and hence why it's a spice and not an herb), and is now most commonly grown for export in India, China, the Philippines, and Jamaica. There are many other countries that grow a lot of ginger, but those are countries that also use a lot of ginger in their traditional cooking (Nepal, Nigeria, Cameroon, Thailand and Bangladesh) and so only a small amount of the total harvest would be available for export. Despite being one of the most commonly cultivated spices around the world, very little is known about the wild populations of this species of ginger (there are four other species in the genus that are commercially sold as "wild ginger," but be careful; the native Canadian species known as wild ginger, an unrelated species to this group, contains potent carcinogens and should never be consumed) throughout its native range in southern Asia around Thailand and Indonesia. There is the presumption, however, that the population sizes are declining due to habitat loss.
Ginger was once believed to be closely related to grasses but now has its own order, the Zingiberales, within the group known as Commenlinids. These are a unique grouping of species within the monocots that includes all grasses, bananas and their close relatives, spiderworts, water hyacinths, and the palms. Quite a diverse group of plants, and a group that most people probably never would have assumed went together. I don't know about you, but water hyacinths (popular ornamental pond aquatic plants with a large bulbous "bladder" at the bottom of the leaves to keep them afloat) and palm trees don't belong in the same group of plants in my mind! But when we compare DNA sequences, these groups of plants do, in fact, make a genetically related group called a monophyletic group. Pretty neat what DNA sequence analysis can show us! Is there something, other than DNA sequences, that demonstrate that these seemingly drastically different plants belong in the same group? Well now that we know they belong, we do actually notice some biochemical similarities between these plants. The most striking of these similarities is the production and storage of ferulic acid in the cell walls of the plant tissues. This type of acid is only produced in this group of plants, and the best part about ferrulic acid? It glows under UV-light. Granted, it is produced in such low quantities that even if you put a grass plant or a palm tree under UV-light you wouldn't notice it glowing but this acid can be extracted and concentrated and used to make things glow. Pretty neat! Ginger plants do share many characteristics with grasses, so I can definitely see why it was assumed they must be very close relatives. They both have the same morphological features with leaf growth and development as grasses: the leaf sheath wraps around the stem (and the stem is actually just composed of concentric leaf sheaths that grow inside one another), forms something called a ligule at the top of the sheath that helps prevent the plant from plant diseases (it acts almost like a piece of tape that prevents anything from getting down between the sheath and the rest of the stem and can be seen clearly in the third photo from the top), and the leaf blade which is the "leafy floppy part" that comes off the stem. The most interesting part about ginger and grass leaves is that each species has its own ligule; they're almost like identification "fingerprints" that can be used by botanists to determine species. Pretty neat that no two species have identical ligules.
If you're an avid reader of my blog (which you should be if you aren't!), you'll have noticed something right away, before barely scrolling past the pictures. The last name of this plant, "officinale," must mean it has medicinal properties! If you assumed that, you would be correct. Common ginger has been used for thousands of years as a medicinal plant, reportedly being able to treat anything from dyspepsia to constipation and colic. Modern scientific research today shows that the rhizome of the plant contains a group of chemicals called gingerols, and these chemicals stimulate the digestive system and cause an increased amount of motility of the gastrointestinal tract. Ginger extracts would definitely help with mild indigestion or mild cases of constipation, but more severe gastrointestinal diseases or disorders have not yet been evaluated for efficacy. There has also been a lot of use of ginger in treating muscle pain associated with intense physical exercise (consumed in China during times of intense building in the 1200s to 1800s, and trekking for materials for these construction projects) and arthritis, and this has also been shown to be somewhat effective in clinical trials. When ginger extract is consumed after a workout, muscle pain post-workout can be reduced by as much as 25%. The catch: ginger extract must be consumed daily, workout or no workout, in order for this effect to be noted. In Canada and the United States, ginger and ginger extracts have made it onto the coveted "generally regarded as safe" lists. So does this mean that ginger is completely safe? Well, like all herbal remedies, you should always check with your doctor before taking them. Ginger in particular causes an increase in bile production as a way of promoting faster digestion. This isn't a problem for most people, but those most sensitive to an increase in bile production will report having heart burn after eating ginger. In cases where someone is sensitive to bile in that they commonly get gall stones, eating ginger every day or taking pills of ginger extracts would be really silly because it would exacerbate the problem. Those with ulcers or inflammatory bowel disease may react badly to large amounts of ginger because of the increased stimulation of the digestive tract, but these reactions are rarely enough to land the person in the hospital (but are unpleasant enough that it is rarely done a second time!).
Despite ginger being such an important plant to many countries around the world, it has yet to make it onto any kind of "national or state/provincial plant" list. This is really too bad for ginger; people who only appreciate ginger for its flavourful rhizome will never get to fully experience the greatness that is ginger. The flowers are absolutely stunning to look at (so delicate and almost transparent the tissue is so delicate, hence my difficulty photographing them), but also could practically knock you over with their intense sweet scent. The flowers open in the evening to attract their nocturnal pollinators, and then are wilted and shrivelled before the evening of the following day.