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Results tagged “colours in plants series”

Jul 31, 2012: Letharia vulpina

Letharia vulpina

Bryant wrote today's entry:

A big thank you to Anne Elliott (aka annkelliott@Flickr) for today's image of Letharia vulpina (commonly called wolf lichen), the last image in the series on plant colour. Letharia vulpina is commonly found in dry coniferous forests across western North America, Eurasia and northern Africa. People have used this particular lichen in a number of different ways over the course of history. The yellow pigment comes from a compound known as vulpinic acid. Vulpinic acid is known to be poisonous to mammals; the source of the common name "wolf lichen" comes from its former use in Europe as a substance for killing wolves. In North America, the species has been used by the Achomawi to make their arrows more lethal for hunting.

Letharia vulpina, with its striking colour, was perhaps more widely used for making dyes and paints (a practice that continues today, though less often). Records show historical use to make dye for woollens in Scandinavia. Also, many North American First Nations made or make use of Letharia vulpina as well. The Klamath, Cheyenne, Karuk, and Yurok nations soaked (or soak) porcupine quills and other materials in a solution of the extracted yellow pigment, with the coloured objects later to be woven into baskets. The Tlingit used/use a solution made from Letharia vulpina to dye fibres for Chilkat blankets. The Apache people used a decoction of Letharia vulpina as a paint, which they made crosses on their feet when moving through enemy territory, with the belief that it made them undetectable. Coastal tribes that were located outside its native range often traded for Letharia vulpina, making it an important lichen economically as well. To read more about traditional uses of lichens, see Ethnolichenology of the World.

The act of temporarily and permanently decorating our bodies with colour is a global phenomenon that is deeply rooted in our fascination/appreciation with plant and other pigments. The role that this cultural fascination has played in the course of history is pretty remarkable. David Lee reminds us that, "...using plant extracts to dye skin and fabric was a major technological accomplishment". Unlike food or most traditional medicine, dyes are usually produced by combining a decoction with other materials that alter the chemical structure, making them bright and permanent. Soon after these techniques were developed, plant pigments and other natural dyes began to be exploited to add vibrance and colour to the people of these early civilizations. Plant pigments helped make warriors appear more intimidating, royalty seem more royal, and added beauty to those who could afford it. Some common historical plant dyes came from Rubia tinctorum (madder), Indigofera tinctoria (indigo), and Caesalpina echinata (Brazilwood). These plants and the pigments they produced were highly prized commodities that drove much of the early trade between Asia, North Africa and Europe. With increased trade also came colonization, where "the colonies provided the raw materials feeding the industrial Revolution in Europe, including fibre and dyes for the great textile mills" (Lee). In the mid-19th century, two students at the school of Justus von Liebig in Germany made discoveries that developed the artificial production of dyes. One of these students, August Kekule von Stradonitz contributed a theory (derived from these discoveries) that played a major part in the foundation of organic chemistry!

Jul 25, 2012: Mangifera indica and cultivars

Mangifera indica cultivars

Bryant writes:

For today's image in the series on plant colour, I am focusing on pigmentation in fruit. I would like to thank 3Point141@Flickr for today's image of three different Mangifera indica (mangoes). From left to right, they are: the wild species, Mangifera indica 'Rosigold' and Mangifera indica 'Cogshall'. Magnifera indica is native to the tropical forests of Asia, although it is now cultivated all over the tropical world. The highly-varied colour seen on the left and centre mangoes are caused by the accumulation of carotenoid pigments, mainly beta-carotene, in the epidermis. The deep red colours seen on 'Cogshall' are caused by the production of anthocyanins, and where the skins appear green is where the production of chloroplasts has persisted.

In nature, fruit colour is a trait that is often the product of co-evolution with the animals that eat the fruit and disperse the seed. Fruits that are more likely to be seen by their animal dispersers are more likely to be eaten, thus their seed is more likely to be spread. Different species of animals have different sensitivities to colour. Birds are highly sensitive to red and black colours, and studies have shown that the majority of fruits that are bird dispersed are black and/or red. Terrestrial mammals, including most primates, are highly perceptive of blues and greens (not reds), therefore larger fruits (such as the mango or the durian) are commonly green in their wild form.

Homo sapiens interaction with plant colour is not so different. As consumers of fruit with a keen eye for colour (in the visible spectrum), we have selected and created varieties of fruit with spectacular colour and spread them far and wide from their native ranges. In the process we have created vast expanses of new, ideal and competition-free habitat (i.e. orchards, farms and gardens) for these species. The mango is a prime example of such a species; it is thought to have been first cultivated outside its native range roughly 4,000 years ago in India. A more classic example, one that is used by both Michael Pollan and David Lee, is the apple. (see: Pollan's The Botany of Desire or Lee's Nature's Palette).

Domestication of formerly wild species often produces a fruit that has a more saturated colour than its ancient relatives. This is certainly the case for Malus 'Red Delicious' ('Red Delicious' apple); in fact colour became such an important trait for 'Red Delicious' that quality of taste was sacrificed in the efforts to produce a skin with higher concentrations of the deep-red anthocyanins. It is interesting to think that the modern forms of food plants are still evolving (due to our selection) to attract consumers.

Jul 24, 2012: Picea pungens

Picea pungens

Bryant wrote and contributed the photograph for today's entry. It's my fault it's late in being posted, but I've been catching up since going on a collecting foray late last week. He writes:

Continuing with the series on colour, I thought I would dip into the more structural side of things. In particular, I want to focus on blue colouration in foliage. Today's photo is of a compact blue-needled selection of Picea pungens, taken in the E.H. Lohbrunner Alpine Garden here at UBC. Picea pungens is a high-altitude species, which grows at elevations between 1,750-3,000 meters in the southern Rocky Mountains. I chose this species because I was intrigued by David Lee's fascination with blue foliage as described in his book, Nature's Palette. Lee's focus is mainly on iridescent blues found in tropical species such as Selaginella willdenowii.

The more subtle blue hues that are found in Picea pungens (commonly the Colorado blue spruce) are not produced by modified anthocyanin pigmentation like the blues found in many flowers. Species like the blue spruce produce a thin film of epicuticular surface waxes on their needles. These deposits diffract light at short wavelengths, which we perceive as a pale blue. This scattering of radiation is a physical phenomenon known as Tyndall scattering--the same reason why the sky and ocean are blue. The surface waxes are thought to reduce the absorption of photosynthetically-active radiation, reduce transpiration, influence gas exchange and lower leaf temperature (see: Physiological Effects of Surface Waxes). These results caused by the diffraction of light by epicuticular surface waxes can be advantageous or disadvantageous depending on the biogeoclimatic location of the individual.

In the case of the Selaginella examined by Lee, the multiple layers of convexly-shaped epidermal cells are what cause the diffraction of a more iridescent blue colour on the leaves. Selaginella willdenowii is a shade-dwelling plant, and the blue iridescence is only found on leaves that are rarely exposed to sunlight. Lee was curious as to why the fern would evolve structures that diffract much of the scarce light that is available to them. After thirty years of pondering this question, Lee's explanation is that the iridescent shade leaves deflect short wave radiation and are thus able to absorb more long wave radiation. This is advantageous in the shaded understory of tropical rain forests, because long wavelength radiation is more available than short wavelength under the canopy.

Jul 19, 2012: Tulipa 'Monsella'

Tulipa 'Monsella'

Bryant continues with his series on colours in plants. He writes:

A big thank you to James Gaither (J.G. in S.F.@Flickr) for contributing today's image of Tulipa 'Monsella'. Prior to reading The Botany of Desire by Michael Pollan, the word "tulip" would make me cringe. It's hard to put my finger on why I disliked them, but it had something to do with how commonplace they are. However, when I look at how Tulipa became so widespread, I feel it is nothing less than extraordinary. It would be a travesty to do a series on colour and not mention the tulip!

Tulipa wild diversity is concentrated in the Tien Shan, Hindu Kush, and Pamir Mountains. In 1554, the first bulbs and seeds were shipped out of their native range to Vienna, where they soon became popular among gardeners. At the time, no flower in Europe demonstrated such highly saturated colours like those found in tulips, and people started to pay higher prices for vibrant varieties. This was the start of what is known as "tulip mania", which began in 1634 in the Netherlands. Tulip mania is now used as a prime example of an economic bubble, or when the price of an asset (such as a tulip) exceeds its intrinsic value. At the height of tulip mania, a single Tulipa 'Semper Augustus' bulb sold for the modern equivalent of roughly 10-15 million dollars! However, this craze didn't last long, and the end of tulip mania came rather abruptly in February of 1637, when buyers refused to show up to the flower auction in protest of the astronomical prices.

Tulipa 'Monsella', pictured above, is not unlike Tulipa 'Semper Augustus', as they both demonstrate a two-tone pattern. However the "broken pattern" in the 'Semper Augustus' tulip was caused by a virus, whereas modern variegated tulips that are commercially sold today are (almost?) exclusively created through intensive breeding regimes. To think that people valued the different colours of tulips so much that they were willing to pay the same price as what a mansion would cost seems absolutely ludicrous.

The Dutch continue to be one of the leaders in the tulip and cut-flower trade, with many global industry transactions occurring in the fifth largest building in the world in Aalsmeer, Netherlands. The floral industry is a multibillion dollar industry, based on a product whose primary asset is colour. In the words of Michael Pollan, "Flowers are exquisitely useless. They're this great froth of extravagance in our lives. But that there is a multibillion-dollar trade in these wonderful, useless, beautiful things is kind of great".

For more information of the tulip trade as well as a look at the industry from the tulip's perspective I highly recommend you read or watch The Botany of Desire, by Michael Pollan.

Jul 18, 2012: Quercus garryana Ecosystems

Bryant is responsible for today's photographs and write-up. He scribes:

The other week, while I was contemplating topics for a series, Daniel handed me a book entitled Nature's Palette by David Lee. The book is written in a combination of scientific and layman's terms, and describes various aspects of colour in plants. It is a fascinating read and provides the inspiration and much of the source material for the following series on plant colour. In this series, I aim to investigate the functional, structural, historical, philosophical, economical and sociological connotations of colour in plants.

The first photograph is of a Camassia quamash meadow with the edge of a Quercus garryana grove in the background, taken at the Mt. Tzouhalem Ecological Reserve on Vancouver Island. The second image was taken at Harewood Plains near Nanaimo, British Columbia. The blues are again Camassia quamash while the pink in the background is Plectritis congesta.

When the Garry oak (or Oregon white oak) meadows and woodlands are in full bloom, they demonstrate some of the most vibrant and extraordinary mass blooms on the west coast of Canada. Unfortunately, Garry oak ecosystems are also among the most threatened ecosystems in all of Canada. When walking through a scene like this, it is hard not to be overcome by a feeling of euphoria, almost as if the vibrant colours have a physical effect on the body. Our appreciation for the beauty of this spectacular bloom is perhaps the reason why there is still Garry oak habitat left, and why there is such a dedicated group of people who protect these remaining sites.

Human attraction to plant colour has existed for millennia. In fact, a Neanderthal skeleton dating roughly 60,000 years old was found buried with concentrated flower remains scattered around the skull, suggesting that a wreath of flowers was placed beneath his head before he was buried. Although there are skeptics of this finding, David Lee is convinced that even the Neanderthals attributed aesthetic value to colourful plants.

More recently, studies have shown that lush landscapes can have beneficial psychological and physical affects on patients in the process of recovering from medical issues. A highly-cited 1984 study observed that post-operative patients recovered more quickly when they had a room with a view of a natural setting as opposed to a view of a brick wall. A more recent experiment, with results published in 2010, concluded that photographs and paintings of a natural landscapes consisting mainly of blues and green are more likely to have a calming effect on hospital patients compared to some types of abstract art.


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