Lots to Know about Willows

The willows are in bloom; they are very early bloomers, beat only by some even earlier flowering plants like skunk cabbage.  Willow flowers don’t, to my knowledge, have petals, and they often bloom before their leaves appear. If you aren't paying attention, it’s easy to miss the entire flowering period of willows.  For a teacher, if you are interested in using willows in your classroom, it may be worthwhile to mark willows in April as to whether the plants are male or female.

My daughter challenged me to find one hundred and one facts to know about willows.  Probably possible, but rather than be boring, I have picked a few favorites in hopes that they might inspire me to think creatively about how to use willows more than I currently do in the classroom. I found this site with some of the great “big picture” facts about willows highlighted:  http://www.people.fas.harvard.edu/~jsavage/Willows.html

To me, willows are a background plant; if you study them enough they do stand out, but if you are just riding your bike down the road, they just look like a bunch of shrubs.  Like every plant (and every person), willows have their own interesting stories to tell but you may need to ask and listen to know the story.

1.  Willows are dioecious; some plants are male,  and some plants are female.

2.  Some willows have been reported to be ambophilous, using wind and insects to disperse pollen (Meeuse, 1978).

2. Over twenty species of willows can be found in Pennsylvania.  http://www.paflora.org/

3. Changes in the chemistry of willow plants may help explain cycling in Lynx populations.

Bryant JP,Wieland GD,Clausen T,Kuropat P. 1985.  Interactions of snowshoe hare and feltleaf willow in Alaska. Ecology 66: 1564–1573.

4.  Willows often like wet areas.

5.  Willows make compounds related to aspirin (Salicylic acid).

6.  Willows are related to Aspen, and I believe that I see the similarity when looking at the hairy buds on the branches. 

7.  Some gall-making insects attack willows, and there are reports that herbivory may differ between male and female plants. Furthermore, willows interact with many insects.  Wonderful pictures can be found here:

http://wanda.uef.fi/biologia/nyman/IOWexternalfeeders.htm

8.  You can make a cheap rooting solution by soaking severed young willow twigs in water for several weeks & then using that water on the roots or cut stem of another plant.

Willows in the classroom?

The capacity of willow plants to make rooting hormone certainly opens many doors to student experiments. 

The vegetative and flower buds of willows, especially “pussy willows” are quite appealing to students – so they provide an opportunity to investigate plant stem anatomy.

Dioecious nature of the plants provides an opportunity to ask questions about sexual dimorphisms in general.  Can you detect differences in allocation to resources between male and female plants? Why do male plants allocate resources different from female plants? Can  you detect differences in herbivory between males and females?

Thinking About Harry Plants While Feeling Harried

Many words exist that describe hairs or harriness of plants.  Here are some that I found:

trichome
pubescent
tomentous
villous
indumentum
wooly
pilose
colleter
felted
floccose
glochid
hirsute
hispid
hispid
penicillate
puberulose
sericeous
strigose
stellate
arachnoid

How are hairs adventageous to plants? In Johnson (1975)'s  review, he concludes that the propensity to make hairs is quite widespread in plants, and suggests that the ability to make hairs is probably genetically available to most plants.  Perhaps in line with the Gould Lewontin's famous essay "The Spandrels of San Marcos", Johnson (1975) seems to hint that hairiness in leaves and stems could be just a correlational effect, a trait that exists more due to the need for root hairs than for any function to leaf and stem hairs.

On the other hand, Johnson (1975) reviews quite an array of advantages that have been proposed for leaf and stem hairs.  Hairs on leaves may reduce water loss from leaves.  Hairs change the reflectance of a leaf, and also the wavelenghts of light absorbed by a leaf.  Taking this information together, hairs on leaves could affect leaf temperature, photosynthesis, and water retention.  Hairness of plants may make them less palatable to predators (Johnson, 1975).  Hairy leaves are not only harder to eat and chew, but they may be less ideal for laying eggs or even for the growth of fungi and bacteria (Johnson, 1975).  Finally, Johnson (1975) suggests that hairs on leaves increase the surface area and may influence excretion of gases, fluids, inorganic or organic solutes.

Today I post a picture of lamb's ear, Stachys byzantina .  This plant is loved by many gardeners and by my children.  Wikipedia suggests that it is native to the middle east.  This plant is a member of the Lamiales or Mints.  Like other members of the family, Stachys byzantina has a tubular flower, five-fused petals, and a corolla that is bilabiate and appears to have two lips.  The bilabiate shape of flowers has evolved more than once so the shape of the flower is perhaps not the best way to identify family.  There are many interesting chemicals and oils found in members of the Lamiales, and likewise members of this family are often aromatic.  The leaves of members of the Lamiales (including Stachys byzantina ) are often opposite, and the stem is often square.  The style of many Lamiales flowers arises from a depression in the ovary.

Click on this picture for a bigger view of Stachys byzantina

Life is busily speeding along, and I can knot afford to spend more than a brief moment on untangling hairy plants; I'm just too harried!   (Comb on, there must be better puns for this topic!)

Gould, Steven J and Richard C. Lewontin. 1979.  The spandrels of San Marco and the Panglossian paradigm: A critique of the adaptationist programme. Proceedings Of The Royal Society of London, Series B, 205: 581-598.

Johnson, Hyrum B.  1975.  Plant pubescence: an ecological perspective.  The Botanical Review 41: 233-258.



Burr Cucumber and Early Successional Environments

Where are all the blogs that I planned to write?  They are lost in the rush of my life.  I appear to have personality traits that are advantagous only in an often-disturbed, early successional environment. I am sloppy, rushed, and eratic.  These traits work fine when the critical deadlines are yesterday, but don't work so well for long term endurance and planning ahead.

I am choosing to blog today about Burr Cucumber.  It seemed to be appropriate that I should blog about an early-successional plant that does well in disturbed environments, and that seems to appear out of nowhere, rush through its plant-life and disappear just a quickly, unable to survive any serious competition or bad weather.

Burr Cucumber is in the genus, Sicyos . How is that pronounced? I wanted to say it "sick", but upon going to this site: I found that the c sounds like an "s".  At the end of the summer, burr cucumber suddenly appeared on our back porch, and in what seemed like just a matter of days, it was lush and big and taking over.  While the plant grew very well, at the first bit of frost, it appears to have died.  (In contrast, our garden pepper plants are still  hanging in there!)  The burr cucumber seems to have more speed than stamina and endurance. The genus belongs in the Cucurbitaceae or Gourd family.  Like some other members of this family it has hairy stems, palmate leaves, and a propensity to climb.  Although the burr cucumbers are not edible, its relatives, the  pumpkins and squashes (both Cucurbita pepo)and cucumbers (Cucumis sativus) are edible.

I haven't keyed out the plant in my backyard, but I suspect that the species growing there is Sicyos angulatus - which is a native weed, and some sites regard it as invasive to fields of nonnative crops. 

This weed reminds me of several topics that I emphasize in my classes.  I bring up climbing plants when I talk about convergent evolution.  Tendrils are one of  many homoplastic climbing traits that plants have evolved repeatedly to solve the same problem:  the need to raise the photosynthetic leaves above the nearby competition.  This plant also displays traits that are advantageous in an early-successional environement:  grow fast and put most of  your energy into growth and reproduction and none into storage; this plant is an annual.  It has not saved any resources to survive the winter; it has reproduced and died.

My life seems to be favoring the "do things quickly"strategy - or at least I feel a pressure to focus more on short-term results than long-term solutions.  And on that note, I redirect my attention away from the pleasant long term goal of learning more about plants, and return my attention to getting a cup of coffee so that I can work faster, burn out sooner, and meet those immediate deadlines of my often disturbed daily routine.

Pictures of Sicyos on my back porch:

Flowers Without Petals: Wind Pollination is Derived in Angiosperms

Flowers without petals: While walking the dog this summer, I tried to take note of all the flowers that are in bloom but which don't have petals. I took pictures of birch, oak, and hickory flowers; last summer I managed pictures of the willow flowers too (and with the help of some students labeled male and female plants along a trail.) The general belief is that the catkins that these plants have are probably, in many cases, examples of convergent evolution. Furthermore, all these flowering plants probably evolved from insect-pollinated ancestors. Wind-pollination is a derived characteristic in flowering plants, but an ancestral characteristic in gymnosperms. Mixed pollination system are probably more common than people realize & the paper below makes me want to keep an eye out for those mixed systems! (New word: ambophily)

Culley, T. M., S. G. Weller, A. K. Sakai. 2002. The evolution of wind pollination in angiosperms. TRENDS in Ecology & Evolution 17:361-369.

I had my daughter tap on the male cones of a gymnosperm in the cemetery while I tried to take a picture. You can kindof see the pollen poofing out. 

The gymnosperms have been wind-pollinated for a long time! In flowering plants, wind pollination is more recent & has evolved repeatedly.

I hope your allergies aren't acting up.

Pollen Sculpturing

Pollen Sculpturing:

The exine or hard outer part of a pollen grain (and for that matter other spores) is often very pretty - some species are known to have distinctive textures, spikes, and indentations. Here's a link to a nice picture on Wikipedia:

https://upload.wikimedia.org/wikipedia/commons/a/a4/Misc_pollen.jpg

Why the fancy surface texture? One possible reason is that those crevices and spikes help chemicals "stick" to the pollen grain. What kinds of chemicals are needed on the surface of a pollen grain? In some cases, chemicals that prevent self-pollination. Today, I am thinking about another common sticky substance found on the outside of pollen grains called pollenkitt. I googled "kitt and German", and it appears that "kitt" is a German word for "putty". That seems right to me. Pollenkitt is a sticky putty that holds pollen grains together.

If a plant is wind-pollinated, then it is better if the pollen grains don't stick together & so wind-blown pollen is expected to have less pollenkitt than animal-carried pollen.

This summer, I found myself surprised by the fact that Forsythia plants and Ash trees are in the same plant family. Forsythia is insect-pollinated and Fraxinus americana (white ash) is wind-pollinated. I wondered if they differ in their pollenkit content as predicted by their pollination systems? I did in fact look at the pollen grains of both under a microscope and was delighted to see that Forsythia pollen had visible pollenkitt and Ash pollen did not. Here's are a few picture (my own pictures):

Possibly because it is important for pollen grains to be coated with chemicals, some plants have evolved very beautiful pollen grains with very interesting surfaces. Maybe this is a stretch, but I can't help but wonder if pollenkitt may be one evolutionary reason why pollen grains are so beautiful.

On a side note: A few years ago I found this link to the work of an artist whose passion for pollen sculpturing has led her to make pollen sculptures.

http://www.jogolesworthy.com/wpimages/wp7ff3213b_05_06.jpg

Supplementary reading:
Dobson, Heidi E. 1988. Survey of pollen and pollenkitt lipids-chemical cues to flower visitors? American Journal of Botany 75: 170-182.

Botany in a modified world - Is every plant worthy to know?

A Quaker philosophy that I try to hold near to me is that every person has an inner light.   Maybe a similar thought can be applied to every plant:  the idea that every plant (or every organism, regardless of taxonomic group) can tell a worthy story.

We live in a world of modified landscapes.  I recall one of my mentors telling me that there are no truly pristine place left on earth.  All habitats are modified.  Another memorable experience was walking through the "old growth" portion of Cook Forest with a naturalist visiting from Germany who kept commenting that the forest was over-browsed by deer, and questioned how the forest could be accurately referred to as "old growth".  Even the least disturbed places on earth have been modified by humans; habitats aren't what they were before there were 7 billion people on earth.  Global climate change will touch every "pristine" place.

I wandered through a local nursery last week, looking at the "native" trees - catalpa, oaks, and even witch hazel.  Although these trees represent native species, the ones at the nursery were still varieties that had been chosen by humans interested in particular traits.  I suspect these garden center/nursery trees harbor different genes from a population genetic standpoint than the original wild populations of the same species 300 years ago.  If I buy one of those trees (which I was thinking of doing) will I be continuing the trend of diluting the locally-adapted gene pools?

I find it overwhelming.  The cup seems more than half empty when my mind tries to grasp the extent that humans have modified the world, and especially when I glimpse of my own role in the process.  It's like catching a view of yourself in the back of a spoon- distorted and ugly; my overuse of resources, my failure to curb and set greater limits on my children's consumer temptations, and so on and so on.

Looking at things from the half-full standpoint is so important.  In a previous post I commented about learning from unredeeming places.  I think I am an unredeeming person at times, but I'm going to go with the belief that all plants and all people, even those most modified & even mass produced by humans, like corn, are still fascinating, and worthy of study, if for no other reason than the love of learning / the joy of gaining basic, unapplied knowledge.

There are two genera of plants that I want to share today.  Each genus has both a native and a horticultural relative that occur in my area.  In both cases, I learned the horticultural variety before I ever discovered the native species, and I think I appreciated the native ones even more because I was already familiar with a close relative.

Impatiens

Walmart sells an abundance of these flowers. They might be hybrids or just highly bred individual species - I really don't know.  They are so commercialized that it is easy to look down one's nose at their artificial colors and their universal commonness.  And yes, they are even a bit invasive; I recall seeing the garden varieties that had snuck into the rainforest in Costa Rica while I was part of an OTS class, but they are interesting plants even despite being so modified by humans.  I especially love to turn the flowers over - the garden varieties often have spectacularly long nectar spurs.

There are two native species in my neck of the woods. Superficially and from a distance, the garden Impatiens look quite different from the native ones, but close up and with the eye of a botanist, some similarities stand out - especially the fantastic nectar spurs.

Impatiens pallida

Impatiens capensis

Spiraea

Most of the year the horticultural varieties (which seem to me to be mostly hedge bushes) in the Spiraea genus are nondescript - almost invisible in their plain background green color and short shrubby stature. Here's a picture of a Spiraea bush blooming near my house. The flowering bush pictured below is probably native to Asia and really doesn't "belong" in Pennsylvania.

Yesterday we kayaked at a state park in Pennsylvania, and lo and behold I was introduced to a native member of this genus. This pretty native Spiraea grows in wet areas.

Spiraea tomentosa

If I were a plant, I fear I would probably be a modified garden variety, mass-produced and similar to so many other plants found in the aisles of Walmart garden center - I am a native want-to-be but I have given in too much to the seduction of modern technology and mass culture. Furthermore, my genes are most certainly transplanted to Pennsylvania through a long history of human colonization.

Maybe the cup isn't quite so empty though, maybe even modified people, modified landscapes and modified plants have a story to tell.  And while it is admittedly a stretch, I think that knowing the modified plants might help us appreciate the native ones even more.  I suppose you could also argue for the potential for restoration of these modified places and things.

Maybe I am justifying and thinking way way too much & maybe I should just simply enjoy every plant and every person without a lot of deep thought!!

Actaea racemosa and racemes

I joined my daughter on a one-day trip to a Girl Scout camp.  While the girls were climbing the rock wall, I was looking for wildflowers in the lovely forest there.  We saw many large flowering Actaea racemosa whose common name is Black Cohosh and Black Snakeroot.  This plant has a long (6 inches or more) raceme of white flowers.  The leaves are divided (compound) and most of the leaves arise from the base of the plant, but some are alternate along the stem.  The mass of multiple stamens spewing out of each flower give you a clue to the plant family - a basil Eudicot, Rununculaceae.

This plant is in the same genus as White Baneberry (Doll's Eye) which is a distinctive poisonous plant of Pennsylvania.

As I tried to key out this plant - I had to distinguish between racemes and spikes.  In a raceme, each flower has a stem or stalk.  In a spike, the flowers are stalkless. For more information visit this wikipedia page:   http://en.wikipedia.org/wiki/Spike_(botany)

Here are some pictures of this interesting plant!