Wildflower Walk: June 2014

I spent last weekend in a cabin outside of Garden Valley, Idaho. I was there for a wedding and so most of my time was occupied with that. However, anxious to explore, I found a brief moment to step out and observe the surrounding plant life. The cabin and an adjacent campground were located in an area that, before the economic downturn in 2008, was to become a major housing development. Because of this (and possibly other things), the area showed lots of signs of human disturbance, particularly the large number of introduced plant species. Fortunately, despite feeling like I was walking through a weedy field, I did come across a few patches of native plants. I may have to return sometime to get a better look at things because I wasn’t able to identify everything that I saw and I’m still not exactly sure what species of lupine and buckwheat I was looking at. Either way, the plants in the following pictures are a few of the things I found.

Aristida purpurea (purple threeawn)

lupinus

Lupinus sp. (lupine)

eriogonum

Eriogonum sp. (wild buckwheat)

amelancier alnifolia

Amelanchier alnifolia (Saskatoon serviceberry)

Don’t let my walk through a weedy field dissuade you. Garden Valley is an incredibly beautiful location. It sits adjacent to the South Fork of the Payette River and near the western edge of the Boise National Forest. It is an area worthy of exploring, which is why I plan on visiting again soon. I recommend you do too.

Previous Wildflower Walks:

Spring 2013

June 2013

American Penstemon Society Field Trip

September 2013

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Ethnobotany: Marigolds

Marigolds are easily one of the most commonly grown annual flowers. They are so common and pervasive, in fact, that they are often overlooked and underappreciated. I, for one, had discounted marigolds long ago, seeking instead for plants considered to be more rare, unconventional, and unusual to place in my garden. But then I started looking into this commonplace plant and, to my surprise, discovered that marigolds have great cultural significance in countries all around the world, both currently and historically. Suddenly, marigolds don’t seem quite so ordinary.

Marigold is a common name for plants found in several genera, but in this case I am referring to plants in the genus, Tagetes, which is in the family, Asteraceae (also known as the sunflower family). Tagetes is a genus composed of at least 42 species, all of which are native to North and South America. Plants in this genus range in height from a few inches to as tall as 6 feet or more. Like most other species in the sunflower family, their flowers appear to be single blooms but are actually clusters of two different types of smaller flowers: ray florets and disc florets. The flowers can be orange, yellow, golden, white, and, in some cases, maroon or with maroon accents. The leaves are usually finely divided and either oppositely or alternately arranged, and the leaves, stems, and flowers are highly aromatic. Marigolds grow in a variety of soil types, even those with minimal fertility. In gardens, they will perform best if they are grown in well-drained soil in full sun and are watered and deadheaded regularly.

Aztec Marigold (Tagetes erecta)

Aztec Marigold (Tagetes erecta)

Even before marigolds gained worldwide popularity, they were commonly used among the people in their native range. They were of particular interest to the Aztecs, who considered marigolds a sacred plant and used them in religious ceremonies. Marigolds became known as the flower of the dead and are still used today during the Day of the Dead to adorn altars and graves. Marigolds were also an important medicinal plant for the Aztecs, especiallly T. lucida, which they used to treat fevers, stiffness, blisters, and various other ailments.

Spanish and Portugeuse explorers were introduced to marigolds by the Aztec people. The explorers brought marigolds back to their homelands and quickly spread them throughout Europe and into Africa and Asia. It was in Europe that they were given their common name, Mary’s gold, referring to the Virgin Mary and the color of the flowers.  At the beginning of the 16th century, Portuguese explorers established a colony in India. The marigolds they brought with them have become a huge part of Indian culture and other cultures in that region. Today there are many large marigold farms in various parts of India, and marigolds are used widely to make garlands and other decorations for weddings, festivals, and religious ceremonies, as well as in foods and dyes.

Marigold Garlands (photo credit: wikimedia commons)

Marigold Garlands (photo credit: wikimedia commons)

The flowers and leaves of marigolds are edible and have culinary and medicinal uses in many countries, especially those in South America. T. lucida and T. minuta are particularly popular for these uses. Marigold flowers have a citrus-like flavor, and T. tenufolia ‘Lemon Gem’ is said to be the best tasting marigold (although, having never eaten marigold flowers myself, I have no personal experience to back that up). The essential oil of T. minuta is frequently used in the fragrance industry and as a medicinal oil. However, T. minuta has also become naturalized in many parts of the world, including Africa, Asia, and North America, and is considered an invasive weed species in these areas.

Marigolds are often planted in vegetable gardens because they are assumed to repel pest insects and/or attract beneficial insects. Little research has been done to back up these claims. The one thing that I was able to confirm is that they have been found to reduce populations of nematodes in the soil. However, just interplanting marigolds among vegetable plants is not enough; instead, a large number of marigolds would need to be planted and then tilled into the soil in order to have the desired effect. Surely marigolds attract pollinating insects, but do they repel pests (apart from nematodes) or attract other beneficial insects?  If you have an answer to this, comment below.

Tagetes minuta (photo credit: eol.org)

Tagetes minuta (photo credit: eol.org)

I have marigolds in my garden this year, partly due to my newfound appreciation of them. If you’d like to see pictures of my marigolds, along with pictures of other things I’m growing, seeing, and doing, subscribe to my tumblr and/or follow me on twitter.

Urban Trees: Unlikely Polluters

Trees are central features in urban environments, and their benefits are numerous and well documented. They give off oxygen and sequester carbon, provide food for urban wildlife, help slow storm water runoff, and provide shade which not only keeps us cool in the hot sun but can help increase the energy efficiency of surrounding buildings. And even if they weren’t doing all these things and more, the aesthetic value they add to our concrete jungles alone is worth having them around. So it is a little disconcerting to learn that the trees we benefit so much from may actually be doing us harm by way of increasing levels of air pollution.

It sounds unlikely, but according to researchers at the Institute for Advanced Sustainability Studies in Postdam, Germany, urban trees can contribute to increased levels of tropospheric ozone, a key component of smog. This occurs when trees emit volatile organic compounds (VOCs), special gasses that are meant to attract pollinators, repel insects, and warn nearby trees of ensuing insect herbivory. These biogenic VOCs react with sunlight and nitrogen oxides (another key component of smog and a result of burning fossil fuels) and form ozone. Ozone in high concentrations is particularly harmful to the lungs, aggravating asthma, increasing susceptibility to lung infections, and damaging the lining of the lungs.

Fortunately, according to the study, certain trees contribute significantly less to ozone production than other trees.  Poplars, oaks, and willows, for example, tend to be high emitters of VOCs, whereas birches and lindens emit much less. Planting low VOC emitters in dense urban areas and keeping high VOC emitters scattered throughout the city instead of planted in large groups will help reduce this phenomenon. A recent article at Scientific American points out that cities that are sunnier and warmer have more to worry about than cloudy and cool cities since sunlight and high temperatures speed up the ozone producing reaction.

Despite this unfortunate discovery, trees still have an important role in cities. Apart from placing and planting the proper trees, our focus should be on finding ways to reduce our fossil fuel emissions which remain the major culprit of our polluted air.

River birch (Betula nigra) - Birches were found to low emitters of volatile organic compounds compared to other common urban trees

River birch (Betula nigra) – Birches were found to be low emitters of volatile organic compounds compared to other common urban trees (photo credit: wikimedia commons)