Tell me your secrets, Witch Hazel

Tags

ecology, flowers, hamamelis virginiana, natural history, nature, plants, pollination, witch hazel

Yesterday, I posted about one of the few plants that I know of that flowers before the vernal equinox.  But I wanted to dedicate today’s post to the only plant I know of that is native to northeastern North America and flowers in the middle of winter.

This is Witch Hazel (Hamamelis virginiana):

Witch Hazel leaves in fall.

Witch Hazel is fascinating for a number of reasons.  It produces an astringent which has cytotoxic properties active against certain cancers, and used for acne.  It was also used to make divining rods (supposedly to find water), but there’s no scientific support for that.

Not *that* Witch Hazel.  This is an excerpt from my Tree Book, which you can find in the “Field Guides” tab.

It has these crazy flowers with long yellow ribbons, and tiny red sepals, that appear in the middle of winter…technically, they flower from September through November, but in urban areas, I’ve seen flowers on them in February during a snow storm.

Flowers in December, with last year’s fruit, image courtesy of the Bedford Audubon Society

The name means “together fruit”, which is descriptive of the flowers being present at the same time as the fruit of the previous year.  Indeed, although the flowers are pollinated in the fall, fertilization does not occur until months after.  Here’s a quote from Shoemaker (On the Development of Hamamelis virginiana, 1905): “Fertilization takes place in May, five to seven months after pollination.”

But there is little else flowering when Witch Hazel is flowering, and that makes it a mystery.  For example, this species depends on insect vectors for pollination, but there are not many insects flying around in November!  Its habit of flowering when through hard frosts and even snow seems odd, and suggests that the benefits of high fidelity visitation outweigh the costs of low frequency visitation.

Naturally, my question was “What pollinates the Witch Hazel flowers?”  The answer seems to be mainly flies, and mainly a tiny fungus gnat (Anderson & Hill 2002):  “A species of dark-winged fungus gnat in the genus Bradysia constituted 42% of all flies collected.“

In other words, because Witch Hazel is the only thing flowering, it is also pretty much the only pollen that insect vectors can be carrying, so every pollen transfer is sure to be the right species.  There is some evidence that this lack of “pollen interference” could be advantageous.

The real clue comes from comparing the flowering of this species with its closely related cousins.  Here’s an explanation from Shoemaker (1905): “In comparing Hamamelis virginiana with its relatives, it seems certain that it was once a spring-flowering plant, whose blossoming has worked backward through the winter.”

What a fascinating plant!

My friend admiring Witch Hazel.

Reaching out

Tags

bumblebees, honeybees, insects, outreach, outreach event, pollination, reaching out, research, science, science communication, teaching, volunteer

I make these for children because children like to hold things and this is a very safe bee!

Sharing one’s research with others is one of the most important, and the most difficult, things for a scientist to do.  There are a lot of ways to communicate research to other scientists (conferences, posters, papers, seminars, abstracts, etc.), but I think many struggle to make their research accessible and appealing to people outside of their esoteric field.

And yet, how can research be valuable if it is not read by others?  There is research for research’s sake, of course, and it is valuable for furthering our knowledge base.  But I feel that, in most cases, it is critical to demonstrate how research can be applied to real problems.  Otherwise, scientists end up in an ‘ivory tower.’  (There was this hilarious Daily Show sketch about the topic, check it out if you have the time and need to laugh today.)

Many of the scientists at my uni study agricultural problems and we can talk directly with farmers, showing them how our research might inform the management of their fields to maximize yield and minimize environmental damage from pesticides and excessive fertilizer usage.

One can also give free public lectures…this being a university town, they are plentiful.  Some scientists communicate with the popular media (with varying levels of success), and some communicate with politicians to try and change policy at national levels.  I have known a couple of scientists who have even given congressional testimony.

But my favourite way of communicating my research to a broader audience involves volunteering to teach children.

Children (and parents) enjoying our display hive of honeybees at an outreach event.

Having worked at a nature center, I have a little bit of experience, and I enjoy working with children.  (Some of my friends tell me that I am good with children, I think the explanation for this is that I am very immature and think like a child.)

Looking for the queen.

Working with kids is fun because they get so excited about things.  One of the outreach activities I regularly volunteer in involves teaching children about insects.  I work in the “insect zoo” where I get to hold Australian walking sticks, tarantulas (not actually insects, but you know how it is) and Madagascar hissing cockroaches all day.

A very sweet tarantula on my wrist (we don't allow the children to hold her...mostly because she is fragile).

The kids never fail to shriek in alarm and delight when they see a 12 centimeter (~5 inches) walking stick sitting in total contentment on my head.  Some of them are brave enough to hold the insects themselves!

A brave child holding a harmless Australian walking stick.

I’ve taught classes about insects and pollinators to groups of students from the little-littles to the cool high schoolers who try to be apathetic about everything and ultimately fail (who try not to react with surprise when I teach them how to pet a bumblebee).

My conclusion is this: we are born with a love of nature and a wonder of natural things.  Encouraging and nurturing this love in children is a sure fire way to ensure that they are eager to protect the natural world!  But we must first reach out to them to share it.

Networks in Ecology

Tags

bee, ecology, mutualism, network, pollination, symbiosis

One of the things that ecologists are interested in is the way that everything is interconnected.   The traditional way of thinking about this is in a food web.  I’m sure you are familiar with this idea.  Plants get their food from the sun, they are eaten by herbivores that are, in turn, consumed by predators, and so on.   It is actually a bit more complicated than a chain, though:

A simple ecological food web.

In fact, real ecosystems are even more complicated.  There is a famous (well, within ecology anyway) study that was trying to demonstrate the reason why the cod fisheries collapsed in the early 1990s.  Here’s the reason:

A cod food web.

Cod are nested within an incredibly complex food web.  How can we predict the effect of altering the population dynamics of, for example, sea cucumbers?

That’s where network analysis comes into play.  What’s a network?  It is a group of interacting components.   That’s delightfully vague, isn’t it?  What I mean is that a network can be just about anything that has nodes (components/nodes/vertices) that interact with each other in some way (edges/links).

You are probably aware of social networks.  WordPress bloggers, for example, form a social network.  When you read this, you are interacting with my blog, etc.  Another very popular example is Facebook.

A global social network of friends as of 2010, by Paul Butler.

In a social network, the nodes are people and their interactions are the ties that link them together.  In a food web, nodes are species and the ties that link them are predatory interactions (one consuming the other).

I study ecological networks based on symbioses, mainly positive ones.  For example, bees and entomophilous (insect pollinated) plants are mutualistic partners.  Both benefit from an interaction.  A bee gets nectar and pollen (food), and the plant gets a mobile unit to move its gametes (pollen).

So, how do I draw a network of bees and flowers?  Looks a little like this.  Start with a bee:

A humble bee drawn by a humble me in powerpoint shapes.

We stand out in the field (haha! don’t think I haven’t been waiting to use that one) and watch flowers.  When the bee lands on a flower:

A visitation event!

We can say that we observed a visitation event.  We don’t actually know if the flower was pollinated, so we make an assumption when we say that it was mutualistic, but it seems like a pretty safe assumption for the most part.

Now we can draw it in a network form.

That bee was seen visiting that flower!

Essentially, this is the simplest network possible.  Two nodes, one interaction.  In this case, the nodes represent their entire species.  A humble bee species visited an aster species (of some indeterminate powerpoint shape taxonomy).

And if we stand out in our field all day (pun intended) watching bees land on flowers (whew, hard work!), then we can get a network like this.

A network of bee and flower species.

Pretty sweet, eh?

You know you love Friday science and puns.

The hidden beauty of pollination

Tags

Bees, hummingbirds, Louie Schwartzberg, pollination, TED talk

For all you bee lovers out there.  This is a gorgeous video.  It’s part of Louie Schwartzberg’s TED talk on pollination, but the video below skips his sappy speech for the good stuff: wildlife footage.

My goodness, how beautiful nature footage is these days!

I hope you enjoy it as much as I do.

PS.  Those lovely bees about 1 minute in are the Euglossini I mentioned in an earlier post.

A less humble bee: the Orchid Bees

Tags

cologne, Euglossini, fragrances, Orchid bees, orchids, Perfume, pollination

[Ed: See my new post about my own experience with these bees when I visited Costa Rica here.]

The Euglossini is a monophyletic (originating only once) clade (group) of Neotropical (New World Tropics) solitary bees (are you sick of parenthetical statements yet?).  Members of the honeybee family, they are some of the most beautiful bee representatives, and they are also the scent masters of the insect universe, which is saying a lot, given the absolute importance of chemical cues to insects.

An orchid bee with an arrow pointing to where it stores the fragrances, photo from Ramirez 2009, Current Biology

But there is a very good reason for their mastery of aromas.  The males of this clade use specific fragrances to woo their mates.  The females are very particular about the cologne they like, and the male must appeal to that specific scent in order to produce offspring and increase his fitness.  Hence the necessity of their skill, and as you know, necessity breeds prodigy.

The bees employ a strategy that perfume makers use as well, called enfleurage (French! The language of love (just kidding (huzzah for nested parentheticals!))), which allows them to extract aromas from plants.  The method is to use a fatty substance to dissolve lipid soluble plant compounds.  (Think soaps and lotions.)  The bees store the fragrance in pockets in their hind tibia, probably adapted from the pollen baskets (corbiculae) of ancestral bees.  Humans sometimes use alcohols to capture the scent from the fats; this is where we get our typical perfumes and colognes.

The world’s most expensive cologne, at $2,350 US, photo from http://www.luxmillionaire.com/2010/07/top-10-most-expensive-mens-colognes.html

The males spend their entire lives collecting fragrances from the rain forest…dead wood, resins, fungi, and especially a group of specially adapted orchids that require one specific bee visitor to pollinate them.  They will fly up to 23 km to find that special chemical combination: the key to unlock the hearts of their lady lovers.

Some of the scents they collect are appealing to humans too!  They collect the aroma of wingetergreen (methyl salicylate), clove (eugenol), eucalypt (cineole), jasmine (benzyl acetate), and balsamic (methyl cinnamate).  After all their hard work, they present their bouquet from a perch and hope that it is the right recipe.

Not so different from humans after all, are they?