Month: July 2015

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Poisonous Plants: Castor Bean

A series of posts about poisonous plants should not get too far along without discussing what may be the most poisonous plant in the world – one involved in high and low profile murders and attempted murders, used in suicides and attempted suicides, a cause of numerous accidental deaths and near deaths, developed for use in biological warfare by a number of countries (including the United States), and used in bioterrorism attacks (both historically and presently). Certainly, a plant with a reputation like that is under tight control, right? Not so. Rather, it is widely cultivated and distributed far beyond its native range – grown intentionally and used in the production of a plethora of products. In fact, products derived from this plant may be sitting on a shelf in your house right now.

Ricinus communis, known commonly as castor bean or castor oil plant, is a perennial shrub or small tree in the spurge family (Euphorbiaceae) and the only species in its genus. It is native to eastern Africa and parts of western Asia but has since been spread throughout the world. It has naturalized in tropical and subtropical areas such as Hawaii, southern California, Texas, Florida, and the Atlantic Coast. It is not cold hardy, but is commonly grown as an ornamental annual in cold climates. It is also grown agriculturally in many countries, with India, China, and Mozambique among the top producers.

Silver maple leaf nestled in the center of a castor bean leaf.

Silver maple leaf nestled in the center of a castor bean leaf.

Castor bean has large palmately lobed leaves with margins that are sharply toothed. Leaves are deep green (sometimes tinged with reds or purples) with a red or purple petiole and can reach up to 80 centimeters (more than 30 inches) across. Castor bean can reach a height of 4 meters (more than 12 feet) in a year; in areas where it is a perennial, it can get much taller. Flowers appear in clusters on a large, terminal spike, with male flowers at the bottom and female flowers at the top. All flowers are without petals. Male flowers are yellow-green with cream-colored or yellow stamens. Female flowers have dark red styles and stigmas. The flowers are primarily wind pollinated and occasionally insect pollinated. The fruits are round, spiky capsules that start out green often with a red-purple tinge and mature to a brown color, at which point they dehisce and eject three seeds each. The seeds are large, glossy, bean-like, and black, brown, white, or often a mottled mixture. They have the appearance of an engorged tick. There is a small bump called a caruncle at one end of the seed that attracts ants, recruiting them to aid in seed dispersal.

Female flowers and fruits forming on castor bean.

Female flowers and fruits forming on castor bean.

All parts of the plant are toxic, but the highest concentration of toxic compounds is found in the seeds. The main toxin is ricin, a carbohydrate-binding protein that inhibits protein synthesis. The seeds need to be chewed or crushed in order to release the toxin, so swallowing a seed whole is not likely to result in poisoning. However, if seeds are chewed and consumed, 1-3 of them can kill a child and 2-6 of them can kill an adult. It takes several hours (perhaps several days) before symptoms begin to occur. Symptoms include nausea, vomiting, severe stomach pain, diarrhea, headaches, dizziness, thirst, impaired vision, lethargy, and convulsions, among other things. Symptoms can go on for several days, with death due to kidney failure (or multisystem organ failure) occurring as few as 3 and as many as 12 days later. Death isn’t imminent though, and many people recover after a few days. Taking activated charcoal can help if the ingestion is recent. In any case, consult a doctor or the Poison Control Center for information about treatments.

The seeds of castor bean are occasionally used to make jewelry. This is not recommended. In The North American Guide to Common Poisonous Plants and Mushrooms, the authors warn that “drilling holes in the seeds makes them much more deadly because it exposes the toxin.” Wearing such jewelry can result in skin irritation and worse. The authors go on to say that “more than one parent has allowed their baby to suck on a necklace of castor beans.” I doubt such parents were pleased with the outcome.

castor bean seeds

Castor beans are grown agriculturally for the oil that can be extracted from their seeds. Due to the way its processed, castor oil does not contain ricin. The leftover meal can be fed to animals after it has been detoxified. Castor oil has been used for thousands of years, dating as far back as 5000 BC when Egyptians were using it as a fuel for lamps and a body ointment, among other things. Over the centuries it has had many uses – medicinal, industrial, and otherwise. It makes an excellent lubricant, is used in cosmetics and in the production of biofuel, and has even been used to make ink for typewriters. One of its more popular and conventional uses is as a laxative, and in her book, Wicked Plants, Amy Stewart describes how this trait has been used as a form of torture: “In the 1920’s, Mussolini’s thugs used to round up dissidents and pour castor oil down their throats, inflicting a nasty case of diarrhea on them.”

A couple of years ago, I grew a small stand of castor beans outside my front door. I was impressed by their rapid growth and gigantic leaves. I also enjoyed watching the fruits form. By the end of the summer, they were easily taller than me (> 6 feet). I collected all of the seeds and still have them today. I knew they were poisonous at the time, but after doing the research for this post, I’m a little wary. With a great collection of castor bean seeds comes great responsibility.

The castor beans that once grew outside my front door.

The castor beans that once grew outside my front door.

There is quite a bit of information out there about castor beans and ricin. If you are interested in exploring this topic further, I recommend this free PubMed article, this Wikipedia page about incidents involving ricin, this article in Nature, and this entry in the Global Invasive Species Database. Also check out Chapter 11 (“Death by Umbrella”) in Thor Hanson’s book, The Triumph of Seeds.

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Year of Pollination: Pollinator Walk at Earthly Delights Farm

Last week I had the privilege of attending a pollinator walk with a local entomologist at Earthly Delights Farm, a small, urban farm in Boise, Idaho. The entomologist was Dr. Karen Strickler, an adjunct instructor at College of Western Idaho and the owner of Pollinator Paradise. A small group of us spent a couple of hours wandering through the farm looking for pollinators and discussing whatever pollinator or non-pollinator related topic that arose. Earthly Delights Farm, along with growing and selling produce using a subscription-based model, is a seed producing farm (and part of a larger seed growing operation called Snake River Seed Cooperative), so there were several crops flowering on the farm that would typically be removed at other farms before reaching that stage, such as lettuce and carrots. The farm also shares property with Draggin’ Wing High Desert Nursery, a nursery specializing in water efficient plants for the Intermountain West, which has a large demonstration area full of flowering plants. Thus, pollinators were present in abundance.

A series of isolation tents over various crops to help prevent cross pollination between varieties.

A series of isolation tents placed over various crops to help prevent cross pollination between varieties – an important component of seed saving.

While many groups of pollinators were discussed, including leafcutter bees, bumblebees, honeybees, sweat bees, hummingbirds, and beetles, much of our conversation and search was focused on syrphid flies. Flies are an often underappreciated and overlooked group of pollinators. While not all of the 120,000 species of flies in the world are pollinators, many of them are. The book Attracting Native Pollinators by the Xerces Society has this to say about flies: “With their reputation as generalist foragers, no nests to provision, and sometimes sparsely haired bodies, flies don’t get much credit as significant pollinators. Despite this reputation, they are often important pollinators in natural ecosystems for specific plants, and occasionally for human food plants.” They are especially important pollinators in the Arctic and in alpine regions, because unlike bees, they do not maintain nests, which means they use less energy and require less nectar, making them more fit for colder climates.

One food crop that flies are particularly efficient at pollinating is carrots. According the Xerces Society, carrot flowers are “not a favorite of managed honeybees.” Most flies do not have long tubular, sucking mouthparts, so they search for nectar in small, shallow flowers that appear in clusters, such as plants in the mint, carrot, and brassica families. Flower-visiting flies come in search of nectar and sometimes pollen for energy and reproduction. While acquiring these meals they can at times inadvertently collect pollen on their bodies and transfer it to adjacent flowers. They are generally not as efficient at moving pollen as other pollinators are, but they can get the job done.

Blister beetle on carrot flowers (a preferred food source of flies). Beetles can be important pollinators, even despite chewing on the flowers as they proceed.

Blister beetle on carrot flowers (a preferred food source of flies). Beetles can be effective pollinators as well, even despite chewing on the flowers as they proceed.

During the pollinator walk, we were specifically observing flies in the family Syrphidae, which are commonly known as flower flies, hoverflies, or syrphid flies. Many flies in this family mimic the coloring of bees and wasps, and thus are easily confused as such. Appearing as a bee or wasp is a form of protection from predators, who typically steer clear from these insects to avoid being stung. The larvae of syrphid flies often feed on insects, a trait that can be an added benefit for farmers and gardeners, particularly when their prey includes pest insects like aphids. Other families of flies that are important pollinators include Bombyliidae (bee flies), Acroceridae (small-headed flies), Muscidae (house flies), and Tachinidae (tachinid flies).

Common banded hoverfly (Syrphus ribesii) - one species of hundreds in the syrphid fly family, a common and diverse family of flower visiting flies (photo credit: www.eol.org)

Common banded hoverfly (Syrphus ribesii) – one species of thousands in the syrphid fly family, a common and diverse family of flower-visiting flies (photo credit: www.eol.org)

Because many species of flies visit flowers and because those flies commonly mimic the appearance of bees and wasps, it can be difficult to tell these insects apart. Observing the following features will help you determine what you are looking at.

  • Wings – flies have two; bees have four (look closely though because the forewings and hindwings of bees are attached with a series of hooks called hamuli making them appear as one)
  • Hairs – flies are generally less hairy than bees
  • Eyes – the eyes of flies are usually quite large and in the front of their heads; the eyes of bees are more towards the sides of their heads
  • Antennae – flies have shorter, stubbier antennae compared to bees; the antennae of flies also have bristles at the tips
  • Bees, unlike flies, have features on their legs and abdomens designed for collecting pollen; however, some flies have mimics of these features
Bumblebee on Echinacea sp.

Bumblebee visiting Echinacea sp.

Another interesting topic that Dr. Strickler addressed was the growing popularity of insect hotels – structures big and small that are fashioned out of a variety of natural materials and intended to house a variety of insects including pollinators. There is a concern that many insect hotels, while functioning nicely as a piece of garden artwork, often offer little in the way of habitat for beneficial insects and instead house pest insects such as earwigs. Also, insect hotels that are inhabited by bees and other pollinators may actually become breeding grounds for pests and diseases that harm these insects. It is advised that these houses be cleaned or replaced regularly to avoid the build up of such issues. Learn more about the proper construction and maintenance of insect hotels in this article from Pacific Horticulture.

A row of onions setting seed at Earthly Delights Farm. Onions are another crop that is commonly pollinated by flies.

A row of onions setting seed at Earthly Delights Farm. Onions are another crop that is commonly pollinated by flies.

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Documentary: The Sagebrush Sea

Last month I posted a few photos of some of the weeds and wildflowers of the Boise Foothills. In that post I touched briefly on the ecology of the foothills, and a few readers expressed interest in more posts about this topic. It is definitely a topic I would like to explore further, but it is not one that I know a ton about. In fact, despite spending the majority of my life residing in this high desert, sagebrush-dominated ecosystem, it has only been in the past few years that I have really gained an appreciation for it. Perhaps that’s understandable. This landscape, which initially appears drab, lifeless, and boring, is not easy to love at first…until you do a little exploring, at which point you find it teeming with life, loaded with diversity, and worthy of admiration.

That is one of the themes of a new PBS Nature documentary, The Sagebrush Sea, which debuted on PBS in May 2015. The film is an intimate view of what’s really going on in this vast, seemingly empty landscape that many of us simply ignore, passing through on our way to somewhere else. It is an introduction to a fascinating ecosystem, shaped and formed by extreme events and inhabited by plants and animals that have unique adaptations that allow them to survive the harsh conditions of the high desert. Some of these plants and animals can be found nowhere else on earth. For anyone looking to learn more about the ecology of the Boise foothills and/or the larger ecosystem of which they are a part, this is an excellent place to start.

The-Sagebrush-Sea

The sagebrush steppe is a plant community dominated by sagebrush (Artemisia tridentata and its various subspecies) and bunchgrasses. At one point it covered as many as 500,000 square miles of western North America – hence “the sagebrush sea” – but human activities have reduced it to half that size. The plants and animals in this ecosystem have been coevolving together for at least 2 million years. Sagebrush is, as the narrator of the film says, “the anchor of the high desert,” living up to 140 years old and helping to ensure that the desert doesn’t become a dust bowl. Sagebrush also provides food and shelter for a great number of species.

The Sagebrush Sea was produced by the The Cornell Lab of Ornithology, so while lots of other plant and animal life get adequate screen time, the birds of the sagebrush steppe dominate the film. One species in particular, the greater sage-grouse, is the star character, driving the film’s narrative and speaking for the protection of this threatened and underappreciated ecosystem.

A view from behind a male greater sage-grouse (Centrocercus urophasianus ) - photo credit: wikimedia commons

A view from behind a male greater sage-grouse (Centrocercus urophasianus ) – photo credit: wikimedia commons

Sage-grouse are endemic to the sagebrush steppes of the intermountain west. They are sensitive to disturbances and are “tied to unbroken expanses of sage.” Their breeding grounds (leks) are large patches of open ground, but when they aren’t breeding (which is the majority of the year) they are taking refuge in the sagebrush and grasses. The females make nests below sagebrush, where they blend right in, camouflaged from predators. Sage-grouse consume various plants and insects throughout the year, but their diet consists mainly of the evergreen leaves of sagebrush. Just 200 years ago there were up to 16 million sage-grouse in the sagebrush sea, today that number has been reduced to around 200,000. Due to such a steep decline, they may soon be added to the endangered species list.

Because sage-grouse are so reliant on healthy, intact, widespread sections of sagebrush-steppe, they are considered an umbrella species. Taking measures to protect them will simultaneously spare and even improve the lives of numerous other species with similar requirements. To begin with, there are a handful of other bird species that nest nowhere else except in sagebrush, specificallly the sagebrush sparrow, the sage thrasher, and the brewer’s sparrow. Other animals feed on sagebrush and rely on it to make it through the winter, such as pronghorn and mule deer. Sagebrush is also considered a nurse plant, providing shade and moisture for grass and forb seedlings growing below it.

The sagebrush steppe is threatened by the usual cast of characters: habitat fragmentation, urban and agricultural development, invasive species, climate change, etc.  Some specific activities like cattle ranching and oil and gas drilling also come into play. While The Sagebrush Sea briefly introduces some of the major threats to this ecosystem, it does not dwell on any single issue or point fingers in any one particular direction. For one, it is hard to place blame when there are so many factors involved; but more importantly, the filmmakers wanted the film to be accessible to everyone in order to foster a greater appreciation for the sagebrush sea and a consequent desire to protect it. The debates regarding this part of the world are heated enough, and those directly involved are already well aware of the issues.

This is a beautiful film. The images it captures are captivating and at times breathtaking. Apart from the sage-grouse, various animal families are introduced throughout, each one stealing your heart. My only complaint is that, at only 53 minutes, the film is too short. Luckily, the world they depicted is right outside my door, and I am now even more inspired to explore it.

To learn more about sage-grouse conservation, visit Sage Grouse Initiative.

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Year of Pollination: Mosquitoes as Pollinators

It is difficult to have positive feelings about mosquitoes, especially during summer months when they are out in droves and our exposed skin – soft, supple, and largely hair-free – is irresistible to them. We are viewed as walking blood meals by female mosquitoes who are simply trying to produce young – to perpetuate their species just like any other species endeavors to do. Unfortunately, we are left with small, annoying bumps in our skin – red, itchy, and painful – risking the possibility that the mosquitoes that just drew our blood may have passed along any number of mosquito-borne diseases, some (such as malaria) that potentially kill millions of people every year. For this, it is okay to hate mosquitoes and to long for the day of their complete eradication from the planet. However, their ecological roles (and yes, they do have some) are also worth considering.

There are more than 3,500 species of mosquito. Luckily, only 200 or so consume human blood. Mosquitoes go back at least 100 million years and have co-evolved with species of plants and animals found in diverse habitats around the world. Adult mosquitoes and their larvae (which live in standing water) provide food for a wide variety of creatures including birds, bats, insects, spiders, fish, frogs, lizards, and salamanders. Mosquito larvae also help break down organic matter in the bodies of water they inhabit. They even play an important role in the food webs found inside the pitchers of northern pitcher plants (Sarracenia spp.). Interestingly enough, Arctic mosquitoes influence the migration patterns of caribou. They emerge in swarms so big and so voracious that they have been said to kill caribou through either blood loss or asphyxiation.

However, blood is not the main food source of mosquitoes; flower nectar is. Males don’t consume blood at all, and females only consume it when they are producing eggs. Any insect that visits flowers for nectar has the potential to unwittingly collect pollen and transfer it to a nearby flower, thereby aiding in pollination. Mosquitoes are no exception. They have been observed acting as pollinators for a handful of species, and could be acting as pollinators for many more.

Bluntleaved orchid (Platanthera obtusata) is pollinated by mosquitoes. phot credit: wikimedia commons

Bluntleaved orchid (Platanthera obtusata) is pollinated by mosquitoes. photo credit: wikimedia commons

The scientific literature describes the pollination by mosquitoes of at least two plant species: Platanthera obtusata (syn. Habenaria obtusata) and Silene otites. P. obtusata – bluntleaved orchid – is found in cold, wet regions in North America and northern Eurasia. It is pollinated by mosquitoes from multiple genera including several species in the genus Aedes. Mosquitoes visit the flowers to feed on the nectar and, subsequently, pollinia (clusters of pollen) become attached to their eyes and are moved from flower to flower. This scenario likely plays out in other species of Arctic orchids as well*.

S. otites – Spanish catchfly – is a European species that is pollinated by mosquitoes and moths. Researches have been studying the floral odors of S. otites that attract mosquitoes, suggesting that determining the compounds involved in these odors “might lead to the development of new means of pest control and mosquito attractants and repellents.”

Northern House Mosquito (Culex pipiens) - one of the species of mosquitoes that has been observed pollinating Silene otitis. photo credit: www.eol.org

Northern House Mosquito (Culex pipiens) – one of the species of mosquitoes that has been observed pollinating Silene otites. photo credit: www.eol.org

Despite the list of functions that mosquitoes serve in their varied habitats, an article that appeared in Nature back in 2010 argues for wiping mosquitoes off the Earth, stating that “the ecological scar left by a missing mosquito would heal quickly as the niche was filled by other organisms.” And even though “thousands of plant species would lose a group of pollinators,” mosquitoes are not important pollinators of the “crops on which humans depend,” nor do they appear to be the sole pollinator of any single plant species [the species mentioned above are pollinated by other insects as well]. Eliminating mosquitoes, however, is more of a pipe dream than a realistic possibility as our “best efforts can’t seriously threaten an insect with few redeeming features.”

*Speaking of orchids and pollination, endless posts could be written about this incredibly fascinating and diverse group of plants and their equally fascinating and complex mechanisms surrounding pollination. There will be more to come on such topics. Meanwhile, it should be noted that orchids are also a notoriously threatened group of plants. To learn more about orchids and orchid conservation in North America, visit North American Orchid Conservation Center.

Read more about mosquito pollination here.

And now for your listening pleasure:

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How to Make Petrified Wood

petrified log 2

So, you want to petrify some wood, eh? Here is a list of the basic ingredients that you will need:

  • A log (or some other chunk of wood)
  • Sediment, mud, volcanic ash, lava, or some type of inorganic material in which to bury the log and create an oxygen-free environment
  • Groundwater rich in silica (or other mineral commonly found in rocks)
  • Additional minerals including iron, copper, and manganese for coloring
  • Time and patience (because this is going to take a while – millions of years perhaps)

petrified log 8

Petrification refers to organic material being converted entirely into stone through two main processes: permineralization and replacement. First, the log you intend to petrify must be buried completely, cutting off the oxygen supply and thereby slowing the decay process considerably. Over time, groundwater rich in silica and other minerals will deposit the minerals in the pore spaces between the cells of the log. Later, the mineral rich water will slowly dissolve the cells and replace them with the minerals as well. The slower the better, assuring that the textures of the bark and wood and details such as the tree rings will remain visible. After enough million years have passed, the log may find itself exposed, pushed out of the ground by an earthquake or landslide or some other act of nature. What entered the ground as a living or recently dead tree, is now 100% inorganic material. And it is much heavier.

The colors in your petrified log will vary depending on the presence and concentrations of minerals in the groundwater. Cobalt, copper, and chromium will create greens and blues. Iron oxides will give the log hues of red, orange and yellow. Manganese adds pink and orange. During the petrification process, various circumstances can cause the silica to form a variety of crystal structures and other formations within the log. These formations can include amethyst, agate, jasper, opal, citrine, and many others. When all is said and done, your petrified log will be a true work of art.

petrified log 1

Petrification is a fossilization process. Thus, a section of petrified wood is a fossil, and it can be used to help paint a picture of what a particular region was like back when the tree was alive. It can also help us gain a better understanding of how life has evolved on this planet. Areas with large concentrations of petrified wood are located throughout the world, each with its own unique story to tell about the tree species once found in the area and the circumstances that led to their petrification. One such location is Petrified Forest National Park in Arizona. The petrified wood found there came from trees living in the area over 200 million years ago.

petrified log 5

Is a few million years too long to wait? Scientists have developed ways to petrify wood in the laboratory in as little as four or five days. One such process was developed at Pacific Northwest National Laboratory about a decade ago. It involves soaking a section of wood in hydrochloric acid for two days and then in either a silica or titanium solution for another two days. After air-drying, the wood is placed in an argon gas filled furnace and slowly heated to 1400° Celsius over a period of two hours. It is then left to cool to room temperature in the argon gas. What results is a block of ceramic silicon carbide or titanium carbide. Probably not as beautiful and interesting to look at as the one that took millions of years to form, but cool nonetheless.

petrified log 6

Read more about petrified wood here and here.

The photos in this post were taken at Idaho Botanical Garden in Boise, Idaho. If you find yourself in the area, stop by and check out their petrified log which was found in the Owyhee Mountains.