Chaparral Yucca, Spanish Bayonet – the many named Hesperoyucca whipplei

Despite the cool breeze blowing off the Pacific visible 1300 feet below (400 meters) and four and a half miles away (7 kilometers), it is hot.  Blisteringly so.  The sun beats down on me heating my skin like the bank of coals left over from a bonfire.  Across the valleys the slopes of the Santa Monica mountains waver in my vision as the rising heat warps the air, changing its density and bending the light.  At my feet what looks like heat shadows dance, but upon closer investigation I realize that it is a 6 inch (15cm) layer of extremely fine alkaline dust blowing over the trail like a Martian sandstorm seen from orbit.

This is one of the most diverse areas of California for birds, but all I hear is a single crow cawing as it glides over the ridge and falls into the canyon to the west of me.  Dressed all in black, even the crows must be broiling.  Here and there fence lizards and side blotch lizards scurry abruptly across patches of orangey dust leaving sharp trails in the fine powder that flies up from beneath their feet and whip-lashing tails.

Only the flies and ants are active; green bottle flies, landing to steal a lick of sweat from my arms before I shoe them away and inexhaustible armies of red ants collecting seeds to add to their larders.

It is the middle of the day, the time when the Chumash sun god grows weary of carrying the heavy bark torch he carries across the sky and stoops under its weight, allowing the flame to fall close the the planet’s surface.

Here and there on the drably greenish slopes pillars of bright white stand proud, like blowtorches, clearly visible for great distances in the bright sunlight.

Chaparral Yucca (Hesperoyucca whipplei) 3/4 of a mile away through a 300mm lens, uncropped.

Chaparral Yucca (Hesperoyucca whipplei) 3/4 of a mile away through a 300mm lens (8.5 zoom equivalent), uncropped.

These 9+ foot (3+ meter) beacons are the  inflorescences of an iconic coastal chaparral plant and the reason why I am walking in heat that even the lizards are avoiding.

This plant has a number of common names and has recently been reclassified and renamed in the academic literature.  The most common name is simply “yucca”, with the “y” portion pronounced as in “ya-all” rather than “you”.  This is not to be confused with “yuca” (pronounced with the “you” sound), the cassava root, a common food found through much of the tropics.

This particular species of yucca is also known as Chaparral Yucca, Common Yucca, Foothill Yucca, Our Lord’s Candle, Quixote Yucca, and, perhaps the most telling, Spanish Bayonet.  I find the latter name to be particularity evocative as the long, lance-like leaves are crowned with a needle-like point that easily penetrates clothing, only to break off under your skin, leaving a mark that itches for days to weeks as your body works the barb back out.

Like many organisms, this plant has been classified and reclassified, the scientific name changing back and forth as new information comes to light.  It is currently known as Hesperoyucca whipplei, a name coined in 1892 by Georg Engelmann, but it spent many years happily living under the name Yucca whipplei, when it was thought to be more closely related to Joshua Trees than recent genetic analysis indicates that it is.  Perhaps I am lazy, but I have always referred to it as yucca, and will continue to do so, relying on context to clarify which of several I mean.

The inflorescence of Chaparral Yucca is a mighty affair, that stands high above the landscape in defiance of herbivorous predators, protected by its height and the spiky ball of needle-tipped blades below.

Unopened buds at the opt ad a yucca flower stalk

Flowers and unopened buds at the top of a yucca flower stalk

A senescent yucca with a 4 foot (3+ meter) ball of blades dying after blooming)

A senescent yucca with a 4 or 5 foot (1-2 meter) ball of blades dying after blooming)

For many years these yuccas, which are monocots (having simple leaves with no branch-like structures in them) were though to be in the lily family (Liliaceae) on the basis of their flower construction which closely mirrors the multiple sets of 3  and superior ovaries that are a characteristic of lilies.  Now the yuccas have been moved into the Asparagaceae family which includes asparagus, orchids, hyacinths, Lily-of-the-Valley, and the close relative agave, known to most people in its cooked, fermented, and distilled form, Tequila.

Superior ovaries and the parts in sets of 3 and 6

Superior ovaries and the parts in sets of 3 and 6 – this flower had fallen onto a different plant

When you look at the flowers of a plant you are looking at its genitals, a thought that should give one pause the next time you buy flowers for your partner.  Unlike animals, plants cannot wander about to seek their mates and thus many must rely upon intermediaries for reproduction.  The various colors, shapes, scents, and sizes of flowers are meant to attract very specific sexual intermediaries.  Brightly colored flowers are often attractants for birds, butterflies, and bees that are active during the day, long tube-shaped flowers attract hummingbirds and insects with long tongues, flowers with fetid scents often attract flies and beetles.  The yucca has relatively large bright white flowers with a slightly sweet, nutty smell.

Bright white yucca flowers - white flowers often attract night flying animals such as moths and bats

Bright white yucca flowers – white flowers often attract night flying animals such as moths and bats

These highly scented, bright white flowers, so visible during the day, are meant to attract night flying creatures.  In this case a very specific moth, the California Yucca Moth (Tegeticula maculata).  The relationship between the Yucca Moth and the yucca plant is one of mutual dependence; despite all the other insects that come to steal nectar, only the yucca moth pollinates the plant.  As it does so, it deposits its eggs in the developing seed pods, where the larvae grow, eating some of the seeds as they grow.  These moths only lay eggs in the yucca seed capsules.  In return for pollination (sex) the plant sacrifices some of its seeds.  At this point, neither the plant, nor the moth can survive without the other.  The specificity of the relationship suggest that it is an old one.

The yucca plant is incredibly useful.  The long leaves are tough and full of strong fibers.  The whole leaves were woven into mats and sandals.  The fibers were separated and twisted into extremely strong cord; numerous time I have done this quickly in the field when I need a length of twine and do not want to cut the cord I carry in my pocket.  The flower stalk is full of water and sugar, the flowers themselves are edible, more than edible, they are delicious with a delicate nut-like flavor with a touch of bitterness, a little like cashew blended with bitter almond topped with a dash of gardenia scent.  The unripe seeds are edible raw or roasted, and the dried seeds can be ground into flour.

It is not only humans that find the plants useful and delicious, deer, rats and birds all like to eat the tasty bits, many getting water in addition to nutrients.

Yucca inflorescence being browsed on by a hungry animal

Yucca inflorescence after being browsed on by a hungry animal

It takes a yucca plant 4-6 years to reach flowering stage, then, like a century plant, it dies shortly after flowering.  Even while it is flowering the leaves begin turning color.

Yucca basal rosette with leaves dying after plant flowers

Yucca basal rosette with leaves dying after plant flowers

New plants grow from runners and dispersed seeds.

The old flower stalks can remain standing for another year or two before collapsing, often with the shredded remains of the seed pods still attached.

Fallen flower stalk with empty seed pods attached

Fallen flower stalk with empty seed pods attached

This is one of the iconic plants of the coastal chaparral environment, one which I admire, but treat with the utmost respect, having spent far too much time digging leaf-spikes out of my legs and arms over the years.

Hummingbirds – miracles of evolution

Of all birds hummingbirds are one of the most fun to watch.  They are fast, colorful, and tiny, the smallest ones roughly the same size as a large moth or butterfly.  They are probably best known for their maneuverability.

Anna’s Hummingbird (Calypte anna) coming in for a landing. Note the small tail, the curve of the body, and the large wing muscles.

These birds are compact and extremely well muscled.  Their tails are short and flexible, notice how the tail of the Anna’s Hummingbird in the above photo is curved to the side and folded to cup the air to assist in guiding the bird in to its landing spot.  Their wings are short with thick muscles covering the limbs and have a range of motion far greater than that of other birds.

The name Hummingbird comes from the noise of their wings beating at 25 beats per second, about 1500 beats per minute. This high wing-beat and the extraordinary wing flexibility allows hummingbirds to hover far more effectively and energy efficiently than any other bird.

To hover they flap their wings in a figure-8 pattern, generating lift on both the down and upstroke.  Approximately 75% of the life of generated on the down-stroke with the remainder on the up-stroke.  The University of Texas has some nice graphs and charts providing more detailed information on how this works.

Anna’s Hummingbird hovering in front of Tobacco Tree (Nicotiana glauca) flowers

In to achieve this maneuverability hummingbirds give up the ability to glide.  In effect they have no low energy flight, they are always running at near full speed.  A 170 pound person would need to eat (and metabolize) 130 pounds of bread a day to keep up with energy output of a hummingbird.  Their energy output is so great that they enter torpor at night, a sort of hibernation.  If they did not do this the hummingbird would starve to death during the night.

Hummingbird flight characteristics are very nearly a blend of bird and insect methods of achieving lift.

Hummingbirds are generally extremely colorful, especially the males.  Like many birds this color is not pigment generated, but is the result of highly specialized feathers light refracting feathers.  Think of oil on water, that rainbow sheen that you see when light reflects from it.  Birds use the same technique, but in a far more specialized way.  Rather than an undifferentiated rainbow of colors the micro-structure of the feathers refracts only specific colors.  The natural color of the feathers is a dark brown, almost black.

Anna’s Hummingbird (Calypte anna) perched on a non-native Tobacco Tree (Nicotiana glauca)

I know I’ve used this photo before, but it illustrates the refraction vs pigment issue well.  The bold purple-pink behind the bird’s eyes is the color we associate with the male Anna’s Hummingbird’s head and gorget (the throat portion).  The dark, almost black, feathers are at the wrong angle to reflect the light and show the natural dark color of their pigment.

The tree in these photos is a Tobacco Tree (Nicotiana glauca), not native to North America, but native to South America, a place where there is a stunning variety of hummingbirds.  This tree and hummingbirds have a long relationship and have mutually evolved to reinforce that relationship.  Hummingbirds and may other birds and insects (and not a few mammals and reptiles as it turns out) drink nectar from flowers.  Not everyone who drinks the nectar will pollinate the plant, thus special relationships evolve.  Plants with long tube-like flowers (penstemon, humming-bird sage, tobacco, monkey flowers, heliconia, etc) are specialized to provide nectar for animals with long tongues that can reach the nectar.

Hummingbird tongue

Hummingbirds not only have long, narrow beaks, they have long, feathery tongues with which to lap up nectar hidden deep inside the tube-like flowers.  As they drink the plant deposits pollen on the beak and sometimes the bird’s head (two photos up you can see the pollen discoloring the hummingbird’s beak).  The next flower the bird visits gets a little pollen from the previous flower and the plant is happy.

A quick look at the shape and color of flowers will often give you a good sense of what type of animal the plant relies on for pollination.

Hummingbird catching insects under a Coast Live Oak

Hummingbirds need protein as well.  Some, such as the Anna’s Hummingbird, catch insects in flight, many others raid spiderwebs for insects.  Here in North America this is a relatively safe prospect, but in parts of South America there are spiders that will happily catch and eat a hummingbird and spin webs more than strong enough to trap the birds.

Hummingbirds have such a need for vast quantities of high energy foods that they are often extremely territorial, engaging in vicious fights and high speed chases.  Like most animals they would rather warn opponents off than waste energy fighting them.  Different species have various methods of letting others know how tough they are.

Anna’s Hummingbird staking out its territory

The little fellow above is marking out territory by fluffing out his head feathers.

One of the most amazing things about hummingbirds to me is that they migrate long distance, some species crossing the Gulf of Mexico in one long flight with no food.  At the shortest distance this is a flight of 480 miles, many birds fly closer to 600 miles to make this open water trip.  For a bird that only weights several ounces, cannot glide, and needs to eat constantly this is a truly remarkable voyage.

On a final note, hummingbirds are far more intelligent than most people realize.  Their memories are phenomenal, allowing them to keep track of individual flowers within their territories and when they were last visited for nectar.  They have the largest brain-to-body size of any bird.

Of Woodchucks (and Lawns)

Lawns.  I am not a big fan of them.  I love meadows, or even lightly tended fields.

Summer rain over a Vermont field full of buttercups (Ranunculus spp.)

I prefer to have a yard rather than a lawn, that flat expanse of close trimmed grass we call a lawn has never been all that appealing to me.  A “yard” does not carry the implication of maintenance that a “lawn” implies.  Lawns are an integral part of American life though, and are found even in places completely unsuited to their presence.  In some areas neighborhood associations mandate how your lawn must look, what you can and can’t have on it, and, in extreme cases, what shade of green it must be and how many inches tall it must be.

There are many theories behind why lawns exist, some people claim that it is a relict of animal husbandry, particularly sheep and how a grazed landscape looks.  Others claim that it taps into some deep species memory of living on a savanna, that the flat, open land is visually soothing and  provides a sense of safety and removal from danger and the unknown.  Some claim that lawns are a symbol of our control over nature, our own private, manufactured landscapes.

The most interesting idea I’ve heard for the prevalence of lawns in the US is in Charles C. Mann’s excellent book 1493: Uncovering the New World Columbus Created.  He suggests that wide, expansive lawns may have been an anti-malaria survival strategy.  A house on a rise on the landscape with cleared land around it would catch the breeze and prevent malaria carrying mosquitoes from getting into the house.  Lawns became embedded in the social consciousness of the emerging United States and spread with the population, as symbolic as the flag or fireworks, though more subtle and having greater practical value.  It is an interesting idea and makes as much, or more, sense as any other idea concerning lawns that I have read.

What bothers me about lawns is that they tend to be uniform monocrops with little three-dimensional texture.  This lack of diversity limits what wildlife visits a lawn, and I, as an ecologist and someone who is always investigating things, love diversity.  My yard here in Vermont is diverse, but my landlord likes a short lawn and cuts it down to an inch or two in height.  Every time he does so all the insects, birds, and mammals flee, taking weeks to return.  I like all those mobile visitors.

Dew covered Funnel-Web or Grass Spider webs (Agelenopsis spp.)

One of the visitors to my lawn is a plump woodchuck (Marmota monax).  It only crosses the road to my lawn when the vegetation reaches 6-8 inches, then it visits nearly every evening and some mornings a well.  This rotund fellow is wary and alert, standing up and peering about at the slightest out of place sound.

Woodchuck (Marmota monax) alert for danger

The name Woodchuck is actually a derivative of a Native American name wuchak, and has nothing to do with either wood or chucking, despite generations of woodchuck chucking wood tongue-twisters.

Woodchucks, also known as Groundhogs, Land-Beavers, and, my favorite, Whistle-Pigs are marmots, large rodents related to ground squirrels.  Most of the marmot family are alpine dwellers, commonly found in high grassy places from Europe to Asia and through North America, but the woodchuck is a lowland species wide-spread in the northeastern and central United States, and through Canada up to Alaska.  Like other marmots woodchucks have a piercing alarm call, a sharp whistle that carries far, sometimes with a bit of a burbling quality to it.

Woodchuck from the rear

Most often a woodchuck will appear as a furry lump on the grass, something like a cross of a loaf of bread, a caterpillar, and a fat otter pretending to be a cat.  Many people have a particular dislike for woodchucks because they eat garden vegetables and ornamental plants.  A good friend of mine has been driven to distraction by one that is eating her hydrangeas.  The one that visits my lawn (but only when it has not been cut for a while) eats the dandelions and fleabane, basically weeding the yard for me.

Woodchuck eating weeds from my yard

During the spring, summer, and fall woodchucks pile on as much fat as they can, much like small bears.  Come winter they retreat to a specially dug winter burrow to hibernate.  Marmots are some of the few animals that enter true hibernation.  They radically slow all their metabolic processes and remain oblivious to the world until mating time, often beginning in February or March, possibly later the further north they live.

Woodchucks have marvelously thick and soft fur, as do other marmots.  I have a hat I bought in western China with a marmot fur ruff that is too warm for me to wear in nearly any weather.  Despite putting on a tremendous amount of fat their flesh is lean, most of the fat is in a subcutaneous layer, just beneath the skin, with the rest stored in the body cavity between the internal organs.

Woodchucks are the most solitary of marmots and are said to be aggressive.  They can be hand raised to be cuddly, but it takes a great deal of effort to overcome their feisty nature.

Surprisingly, woodchucks are reputed to be agile climbers in an emergency, though I have yet to see one scale a tree.  Most often what I see is one popping up to look about:

Wary woodchuck watches for danger

Followed by a rapid retreat if I am not careful, quiet, and slow moving:

Just too dangerous around here…

I like this occasional visitor to my yard, and, given the option, do not mow my lawn as if I do it will not come by to visit.

Mainly because it is silly – if the animation is not working, click the image

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A note:  my posts may become a bit erratic for a few months, I am in the midst of finishing one job, moving (maybe twice), and will hopefully be beginning a new job in a different country.  Eventually this will provide great material for the ongoing exploration of nature, but the route there may be a little irregular and unpredictable.  Bear with it, I will not abandon my writing and photography.

Glaciers and Camel’s Hump

Glaciers, geology, and meteor impact craters have always fascinated me.

Right now I live in New England, a landscape that was recently, geologically speaking, glaciated.  It has been about 12,000 years since the large glaciers here melted, leaving nothing behind but water, exposed bedrock, and a rubble of loose stones of various size and mud made from pulverized stone.  Plants raced for the freed nutrients and the forest wandered north with them.

Now Vermont is thickly forested up to all but the highest peaks.  Despite this signs of that past glaciation are everywhere, from large landscape features to the fine scale distribution of plants across that landscape.

One of the most prominent glacial features is the mountain Camel’s Hump, which, though not tall, can appear to loom over Burlington despite being 20 miles away.

I think it’s the implacable power of a glacier that awes me.  Large glaciers are otherworldly in a way that is difficult to convey.  The best description I have heard was in southeast Alaska where the large ice-fields are said to be the home of  the dead.  I spent two months working with a small group of people on the ice and it was easy to see why people said that.

Camel’s Hump, the mountain in the distance is a little over 4000 feet tall.  That’s a bit less than a mile.  At the height of the last glaciation the ice was more than twice that thick, burying Camel’s Hump so completely that you would only be able to tell it was there by looking via radar, sonar, or gravity scans.  If you were there, you would be standing more than a mile above the mountain top looking at a flat white plain stretching past the horizon in all directions.

That vast depth of ice weighed an enormous amount and moved under its own weight, slowly flowing across the landscape.  Glaciers are continually melting and the streams refreeze elsewhere.  Some of this water finds its way to the bottom of the glacier and refreezes in cracks in the underlying bedrock the glacier has just scoured clean.

Water expands when it freezes and fragments of the bedrock were broken free and held, frozen into the bottom of the glacier.  These entrained rocks scour the bedrock, like a file on metal, wearing it way, grinding it up, and tearing it loose.  The shapes a glacier carves the land into are extremely characteristic and have their own specific names; col, cirque, esker, moraine, drumlin, chatter mark, arête, roche moutonnée, and many more.

The glaciers that covered the New England landscape were large and the features they left are correspondingly large.

Camel’s Hump is a textbook example of a large roche moutonnée.  Roche moutonnée are low, rounded humps of bedrock rock that are ground into their shape by the action of a glacier.  I assume roche moutonnée owe their name, “sheep rocks”, to French and Swiss sheep herders who would have spent a lot of time looking at these low, rounded rocks while thinking about sheep.

The shape of a roche moutonnée shows the direction of glacier flow, and from Camel’s Hump you can see that the ice flowed from the north to the south, from right to left in the photo above.

The northern surface has been ground to a shallow angle, while the south side is steep and jagged, where the glacier ripped cathedral sized chunks of rock loose.

There is a clear vegetation line on the mountain, hardwoods lower down, evergreens above.  In Vermont the vegetation line is due primarily to temperature, moisture, and elevation.  In areas more recently deprived of their glaciers the bands of vegetation climbing the slopes provide an accurate means of dating how long it has been since the glacier left.

Nothing in nature is random, the glaciers don’t just carve their way willy-nilly across the land, their actions are directed by the bedrock they are so eagerly tearing asunder.  Camel’s Hump was a mountain before the glaciers came, and the glacier could only modify what was there, not make something completely new.

Seen from the south side, where the freeze/thaw and continual motion of the glacier have exposed the mountain’s heart you can see the folded, pastry dough like layers of rock that make up Camel’s Hump and the Green Mountains.

The tree covered slope beneath the cliff is a a boulder field dropped in place as the glaciers melted, now colonized by spruce and moss.