Chert – the birthstone of our species

Few types of stone have as long lasting and intimate relationship with our species as do those of the chert family.  Humans have been using this hard, glassy stone continuously to make tools since the time of Homo habilis, some 1.5-2 million years ago.  Our neolithic ancestors mined chert using fire to crack the stone (see video to see how it was done), at least 33,000 years ago at the Nazlet Khater site in Egypt chert was extracted from subterranean mines,  and flint (a type of chert) was used before we had matches to make fire, today we use crushed chert as the abrasive on some sandpapers, and to extract exquisitely detailed micro-fossils from the distant past.  When I worked as an archaeologist near Santa Barbara most of the projectile points, stone awls, and cutting tools we found were made from chert.

What is this “chert” we have been using so assiduously for the last 2 million years?

Chert is a microcrystalline stone made of silicon dioxide (SiO2) with a cryptocrystalline structure (crystals so fine that they are difficult to see even under a microscope) that lacks cleavage planes.  One of the most useful, for us, aspects of cryptocrystalline materials such as chert is that when they are struck they shatter in a predictable conical manner (conchoidal fracturing).  Obsidian and plate glass share this characteristic, making them and chert excellent for making extremely sharp stone tools.  Chert is more common than obsidian, but still rare enough that it was traded over great distances.  Another beneficial aspect of chert is that it is extremely hard, raking a 7 on the Mohs scale.

A number of well known minerals fall into the chert category: flint, jasper, radiolarite, chalcedony, agate,  and onyx are all types of chert, each with specific characteristics that give them enough difference from each other to warrant specific names.  The famous (and expensive) sharpening stones from Arkansas are made from novaculite, a porous, metamorphosed chert that makes an excellent abrasive.  Flints tend to be high quality cherts that are found specifically in chalk or limestone; these are deposited diagenically (via silicon replacement).  Chalcedony, agate, and onyx are a nested subset of minerals with chalcedony, a fibrous form of chert, being the parent of the group.  Jasper is usually found in association with volcanic activity and is sometimes considered to be under the chalcedony subset.  Jasper, agate, and onyx are popular semi-precious stones used for jewelry and sometimes intricately carved.

Red jasper cameo of Medusa by Benedetto Pistrucci (source)

What got me started thinking about cherts once more was a short day-hike I took with a friend in the Marin Headlands, those steep sided hills to the north of San Francisco that are so often obscured by the thick maritime fog.

Marin Headlands and the Golden Gate bridge partially hidden by fog

Marin Headlands and the Golden Gate bridge partially hidden by fog

The Northern California coast has a complex geology and is undergoing a number of divergent changes simultaneously.  This is an emergent shoreline (Geology of Northern California chapter 10, page 37), a place where the land is slowly rising in elevation.  Rising lands often suffer from high rates of erosion and the California coast has an even more drastic set of factors contributing to the erosion rare than merely rising land.  The bedrock is fractured by many faults, weakening the stone, earthquakes (most extremely minor) shake rubble loose periodically, and both wind and water eat away at the ocean facing slopes.  In addition, the sea level has risen several hundred feet since the last glaciation twelve thousand years ago, and the surf is greedily pounding on the hills, tearing parts of them away.

If you watched the video you probably noticed that the chert they were mining peeled off in plates, indeed that the whole formation was made up of sheets of stone layered atop each other like pastry dough.  About 50% of rock in the Marin Headlands is chert and has a similar texture.

Radiolarin ribbon chert cliff showing soft folds and a sharp fault-line cut

Radiolarite chert cliff showing soft folds and a sharp fault-line cut

This is ribbon chert, more formally known as radiolarite chert.  It gets the latter name because it is a biogenic stone made from the semi-gelled skeletons of radiolaria, a type of plankton that builds a silica based support structure.  These this rock was laid down over a 100 million year span beginning 200 million years ago and is filled with tiny fossils of the radiolaria.  Supposedly some of these are large enough to see with a standard hand-lens.

The folding tells us something interesting.  The folds in the above photo are smooth, meaning that this probably slumped slowly while it was still ductile.  Portions of the cliff have sharp folds where the rock broke, indicating that those deformations most likely happened more rapidly and after the stone had lost much of its ductility.

Red and greenish/blue indicate iron, either in oxodised or reduced form

Red and greenish/blue indicate iron, either in oxidised or reduced form

Much of the chert here is red, but there are many patches of vibrant blue-green and aqua as well.  The colors in chert indicate trace amounts of other minerals.  The red and the lovely greenish-blue are both indicators of iron, the red indicating that the iron has oxidised, the blue-green that it has been reduced (had the oxygen removed from it).  This is similar to the mottled gleying that one sees in wetland clay soils.  I am particularly fond of the blue and green colors in chert, perhaps because they are a bit more rare than the red.

Close-up of blue/green chert bands

Close-up of blue/green chert bands

The hardness of the chert leads to beaches with an interesting texture of sand, more like tiny glossy pebbles than the standard sand.

Chert sand

Chert sand

The combination of colors on the cliffs, beach, sky, and ocean make for a nice combination as well.

Tennessee Valley beach in the Marin Headlands

Tennessee Valley beach in the Marin Headlands

We have been using chert for nearly as long as we have been using tools, close to 2 million years now with no sign of slowing down.  If our species had a birthstone it would probably be chert.

California Condors, Megafauna, and Trophic Cascades

A long time ago I worked as an archaeologist near Santa Barbara.  I spent most of my days in the field excavating Chumash sites, recording evidence of looting, drawing maps, and hunting for unknown sites.  It was a fun job, I learned a lot, and it was my first exposure to California Condors.

The Chumash left behind a repository of exquisite petroglyphs, painted and carved into the soft sandstone that makes up much of the Transverse Range, an east-west oriented set of coastal Southern California mountains.  One of my jobs was to preserve this rock-art.  In the dust that makes up the floor of the caves and shelters the art is painted lives a bacteria that eats the organic pigments in the paint used by the Chumash.  Visitors would unwittingly kick up the dust, spreading the bacteria and speeding up the degradation of the rock art.  At several sites we paved the floor with stones to trap the dust.  One of these sites was Condor Cave in the San Rafael Wilderness; I’m sure you can guess how it came by that name.

Condor art at Condor Cave – from http://www.parks.ca.gov

It wasn’t until several years later I when was backpacking in the Ventana Wilderness with a friend that I saw my first wild California Condor.  We stopped and sat, mesmerized, watching five large birds swoop and soar around us.  Of course my camera was acting up at the time and the only photos I got were pathetic to say the best.  The experience stuck with me, all the more so because I had been studying anthropology and repercussions of the North American megafauna extinctions.  

About a week ago I was driving from San Francisco to Los Angeles along HWY 1.  It was one of those spectacular California days where the coast is shrouded by pockets of thick fog broken by regions of bright sunlight and the Pacific Ocean lives up to its name lying tranquil in its bed.

Sun, fog, and kelp-beds along the coast between Morro Bay and Big Sur

Sun, fog, and kelp-beds along the coast between Morro Bay and Big Sur

This stretch of road is made up entirely of corners and as I rounded one I saw a pocket of people pulled over in a turn-out looking up at something on the hill-side.   I caught a glimpse of a large bird on the slope, pulled over at the next turn-out, grabbed my camera, and jogged back to find a very calm California Condor sunning itself in the late afternoon light.

California Condor soaking up the last of the sunlight

California Condor (Gymnogyps californianus) soaking up the last of the sunlight

The California Condors are in rough shape.   DDT, hunting by mis-informed ranchers who believe that condors killed calves, egg collecting, habitat loss, and lead-poisoning are all implicated in modern times for the low numbers of  the California Condor (Gymnogyps californianus).   Additionally, these long-lived birds have small clutch sizes (few eggs per breeding cycle) and reproduce extremely slowly; so slowly that a 1996 study by the Fish and Wildlife department found that it would take 1800 years at the current population growth rate of 1.0003 to achieve a stable wild population of 150 individuals.  This low population growth rate is part of why there is a captive breeding program.

California Condor (Gymnogyps californianus) in the Los Padres National Forest

California Condor (Gymnogyps californianus) in the Los Padres National Forest

In historic times the California Condor ranged from British Columbia to Baja, but during the 19th century its range was rapidly diminished to include only California.  Through captive breeding and release strategies the range has been re-expanded and now includes Arizona, northern Mexico, and a little of Utah, in addition to California.  These birds have what is known as a “relict distribution”, that is, they occupy only a fragment of their former range.

California Condor range map - from: IUCN Redlist http://www.iucnredlist.org/

California Condor range map – from: IUCN Redlist http://www.iucnredlist.org/

 

While it is certainly true that lead poisoning, DDT, and all the rest have been massively detrimental to present day condors this overlooks a very important aspect of the condor niche.  These are large birds, the largest flying birds in North America, with up to a 9.5 foot (2.9 me) wingspan and weighing up to 23 pounds (10.4 kg).  These birds are meat eaters and they need a lot of meat.  The historic population was highest along the coast, where aquatic megafauna would, and still does wash up on the beach.  Beached whales, elephant seals, sea lions, dolphins, seals, and large fish may be disturbing to see, but they provide a wealth of food for bears, foxes, coyotes, weasels, wolves, eagles, gulls, ravens, and condors.  It is true that there are still large gatherings of sea mammals along the coast, but it is also true that there are far fewer of them than there used to be and this has imparted an additional stress to the condors, among other species.

Northern Elephant Seals (Mirounga angustirostris) on the California Coast

Northern Elephant Seals (Mirounga angustirostris) on the California Coast

For birds further inland other sources of meat were, and are important.  Terrestrial megafauna is what fed and feeds inland condors.  We have nowhere near the diversity nor the biomass of large free-living terrestrial animals than we did even a few hundred years ago, let alone what we had when humans first arrived in North America.  Shortly after the arrival of humans most of the large animals, the megafauna (generally being defined as an animal with a body-mass greater than 100 pounds (45 kg) began going extinct.  The giant beavers disappeared, the mastodons vanished, the giant sloths, camel relatives, giant tortoises, horses, and various species of deer were wiped from the continent, and along with those animals also went other animals that relied upon them; dire wolves, saber-toothed cats, short-faced bears, American lions, American cheetah, tetratorns (think condors on steroids), dung beetles, and condors.

Tule Elk (Cervus canadensis ssp. nannodes) being restored to California grasslands

Tule Elk (Cervus canadensis ssp. nannodes) being restored to California grasslands

There is vociferous disagreement as to why the megafauna went extinct, but many, if not most, scholars believe that humans hunted these animals to extinction.  Humans arrived during an ice age and the rapid change in climate (rapid in an evolutionary sense) may have placed the animal populations in a position where enthusiastic hunting had a greater impact than would be otherwise expected; but whatever the exact details the short story is that humans arrived and within a few thousand years a majority of the megafauna went extinct.  This triggered what is known as a “trophic cascade”.

You can think of an ecosystem as being analogous to a game of Jenga.  All together the blocks form a solid tower, but as you remove blocks (species) the tower (ecosystem) becomes more and more unstable.  Eventually one too many blocks is removed and the whole structure comes tumbling down.  In essence, this is what a catastrophic trophic cascade looks like.  So many animals were removed from the ecosystem that now, eleven thousand years later, we are still seeing some of the effects.  Just as blocks you never touched in the Jenga game come tumbling down, species of plants, insects, and animals that were never hunted went extinct or had their life patterns radically altered.  Some plants lost their ability to disperse their seeds, forests and grasslands were no-longer grazed as heavily and the composition of species changed drastically, watersheds and rivers changed their patterns, soils changed as they were walked upon by different animals with different behaviors, concentrations of bacteria and fungus changed, altering soil and groundwater chemistry.  Trophic cascades are a big deal.  They are ongoing, but operate in the background, running smoothly and unnoticed until something breaks the chain of events and the whole tower of blocks comes tumbling down.

The current narrow range of Condors is due, in part to the cascading effects of the megafuna extinctions and more recent changes brought by colonizing Europeans.  We know from the fossil record that prior to the megafauna extinctions several species of condors lived in North America over a range that includes the historic range of the California Condor and stretched across the southern states and up the east coast to New York.

Prehistoric US fossil sites for North American condors, courtesy of the San Diego Zoo library

Seeing the California Condors in the wild is like catching a brief glimpse into the distant past, a time when North America had wildlife diversity to rival that of Africa.  The fate of the condors is far from certain.  They are from a time and place that no-longer exists and it remains to be seen if they can adapt to the world as we have made it, even with our assistance.  I hope the condors do succeed, the world is a richer place and better place for their presence.

Preening in the late afternoon sun

Preening in the late afternoon sun

Tides, Why Tide Charts Don’t Average to Zero, and Agendas

Tides are an important part of life on earth. Earthly tides are primarily governed by the moon, a result of Lunar gravity tugging on the planet as the Earth spins along side of our over-sized neighbor.

A few days after the 2013 "supermoon"

A few days after the 2013 “supermoon”

Tides affect both the earth’s crust (raising it enough so that large particle accelerators must be designed with the geo-tide in mind) and, more familiarly, the oceans. Technically speaking, all bodies of water are affected by the tides, but the large tides experienced by coastal dwellers is a result not only of the Earth-Moon-Sun gravitational dynamic but of resonance, coastline shape, and of characteristics of the ocean floor.

Resonance is simply the self-reinforcing effect of synchronization. The most familiar form of resonance for most people may be pumping your legs on a swing. If your timing is right the small amount of energy added to the pendulum motion by pumping your legs will lift you higher and higher. If your timing is off you can kill your speed and come to a stop. You can do the same with your hand and a basin of water, a small amount of hand motion will quickly wind up sloshing water out of a bathtub. Swings, tides, and lasers work on this principle of resonance.

The shape of the coastline and the depth of the ocean floor can concentrate or diffuse tides as well, focusing or dispersing the vast energies at play. This is why the tides in places with fjords like British Columbia and Norway can be so dangerous.

I grew up near the ocean and spent a lot of time watching the ocean and exploring tidepools and the rocky beaches of the California coast.

Mussels anchored on exposed rocks in the intertidal zone.

Mussels anchored on exposed rocks in the intertidal zone.

The interesting part of the coast was not the sandy beaches, but the craggy high surface areas that trapped pools of water. All sorts of creatures live in these pools. Strange and wonderful creatures like the Gumboot Chiton, Cryptochiton stelleri, large molluscs that crawl out of the water at low tide to feed on exposed seaweed.

Cryptochiton stelleri, or Stellars's Hidden Chiton, so named because the characteristic eight bony plates are hidden under rugose red skin

Cryptochiton stelleri, or Stellars’s Hidden Chiton, so named because the characteristic eight bony plates are hidden under rugose red skin

In tidepools I have found and caught octopus, eels, and fish, but two of the most common residents are Shore Crabs

Shore Crab, a common California coast resident

Shore Crab missing an arm, a common California coast resident

and anemones, both hovering between the scavenger and hunter niches.

Anemones: close-up of arms

Anemone: close-up of arms

These and many other creatures live in what is known as the intertidal zone, the region of the coast that is above low tide and below high tide. This is an area of tremendous free energy. Energy is a two edged sword as any scientist or engineer can attest to. Energy makes all things possible, and most things can be broken down into either growth or destruction. Creatures that live in the intertidal zone reap the benefit of straddling two environments, feasting on the windfall of both, but the fierce waves and tides also expose them to the dangers of being left to suffocate in water, desiccate in the sun, be torn from holdfasts, and fall prey to other adaptable creatures. Excellent potential for great growth or swift destruction.

In the intertidal zone there are bands of life that roughly conform to the amount of time spent out of water. Mussels and barnacles occupy the upper reaches and are the most familiar.

Mussels and Gooseneck Barnacles on exposed rocks.  Both are tasty to eat.  Mussels are commonly eaten in the US and Gooseneck Barnacles fetch high prices in Spain, where people risk their lives to collect them.

Mussels and Gooseneck Barnacles on exposed rocks. Both are tasty to eat. Mussels are commonly eaten in the US and Gooseneck Barnacles fetch high prices in Spain, where people risk their lives to collect them.

Lower down, in some places, Sea Palm grows in dense stands, often damaged by the waves.

Sea Palm (Postelsia palmaeformis), the only species of this kelp and one of the few that can live for extended times out of water

Sea Palm (Postelsia palmaeformis), the only species of this kelp and one of the few that can live for extended times out of water

At each level a different selection of species dominates creating a many-layered composite of ecotones, much like a mountain in miniature. The vertical ranges for these species collections is so narrow that it can be used to track sea level changes.

If you want to see nudibranchs, octopus, and sandcastle worm, then when do you go to the coast?

sandcastle worm (Phragmatopoma californica) colony

Sandcastle Worm (Phragmatopoma californica) colony

Clearly you go at low tide… but what does this mean?

One of the things that bothered me about tide-charts (like the one below) is that if you average the high and low tides you do not get zero.

Graphical tide chart made with the TideTrac app

Graphical tide chart made with the TideTrac app

I went out a while back to experiment with day-time long exposure photos. This is the tide chart for the day. Notice that the lowest tide of the day is still +0.4 feet (12cm)? The average tide for the day is +2.9 feet, nearly a meter. What is that all about?

The answer is that tide charts were designed for sailors, not tide-poolers or surfers. Tide charts are set by a datum, one of 17 potential datums, that all are based off of the LOWEST tides, not the average tide. For a sailor who wants his boat to stay in the water and not be slammed against rocks, this is important.

Even a small bump carries a lot of energy

Even a small bump carries a lot of energy

For the rest of us, it is a little non-intuitive. We have picked the lowest tide as the datum because that is what was important to the people making the charts at the time. If it had been house contractors instead, the datum would have been the highest tides. Tide-poolers would probably have picked the average tide as the datum, making it easy to determine when the most species would be exposed at any given moment.

There is a lesson here; be wary of maps and charts. Maps and charts are made to tell a specific story, a story with a perspective, a message, and an agenda. Like an advertisement on TV or a political speech, it is important to be aware of both the audience and the proponents of the product. And in truth, there is little that is more political than maps and charts.

Oh, the long exposure photos turned out great.

Ten seconds of waves washing in and out during the day

Ten seconds of waves washing in and out during the day

***

Note: for those of you who look at the full-sized photos, several of these have been pulled from my archives and were taken with my first digital camera; a Canon ELPH from the early 2000s. A great little camera, but of a disappointingly low resolution.

Miniature Monitor-like Lizards

The coastal California chaparral is surprisingly noisy.  It is a densely populated place, dry and full of debris with many year-round inhabitants.  In the morning and evening birds warble, coo, chirp, and call to one another.  At night insects buzz, owls hoot, and coyotes hold long-winded conversations.  During the day crows and scrub-jays go about their errands chatting to themselves while hawks soar high above screaming at the sky.  On hot days seed-pods pop open, sending a tinkling rain of potential life through tough branches to the ground and all the plants talk when the wind blows.

Below all, down amongst the leaf-litter and rocky debris, little things, lizards, insects, mice, and small birds scurry back and forth, sending out a diminutive cacophony of rustles and scritches.  The most common of these noise-makers are lizards.

During the summer months the lizard I see most often is a lean, elegant Teiid lizard, the Coastal Whiptail (Aspidoscelis tigris stejnegeri).

Coastal Whiptail lizard (Aspidoscelis tigris stejnegeri)

Coastal Whiptail lizard (Aspidoscelis tigris stejnegeri)

These feisty fellows spend much of their time hunting in leaf litter and gravel, often along the margin of vegetation clumps.  Like many lizards, they have a twitchy, wind-up-toy manner of moving characterized by rapid, jerky motion followed by periods of complete stillness.  Their long tails and powerful legs churn the ground as they move, generating more noise than seems likely considering their size.

A full grown coastal whiptail can be a foot long including the tapering tail from whence their name is derived.  For California this is a decent sized lizard, but nowhere near as large as members of this family of lizards, the Teiidae, can grow.  In South America relatives of the California Whiptail, the Tegu (Tupinambis) lizards grow to four feet and are key predators of young cayman (a large alligator-like predator).  Teiid lizards look and behave very much like monitor lizards.  This may be one of the reasons I am so fond of the whiptails; it is easy to scale them up in your mind and imagine the chaparral landscape as a realm where buffalo sized lizards roam the earth.

Unfortunately, or perhaps not, this is not the case.  Rather than dinosaur sized tracks pressed in the ground, the dusty portions of trails hold the slender marks of dragged tails and little lizard feet.

Lizard tracks in the sand

Lizard tracks in the sand

Like snakes and monitor lizards the Teiid lizards have forked tongues.

The tip of the Coastal Whiptail's tongue is forked, but is difficult to see

The tip of the Coastal Whiptail’s tongue is forked, but it is difficult to see

The question of why certain reptiles have forked tongues has led to a wide variety of strange ideas through history, but the truth of the matter seems to be that the tongue is part of a directional chemical sensor.  The sensory apparatus is the vermonasal organ which is located more-or-less on the roof of the mouth.  Non-volatile chemicals are deposited on the tongue which is withdrawn into the mouth, depositing the chemicals onto two pads at the opening of the tongue protecting sheath.  From there the chemicals are transferred to the vermonasal organ when the reptile closes its mouth.  The difference in concentration of the collected chemicals provides the directional sense.  In essence these fellows are playing “warmer-colder” in pursuit of their prey.

Like many lizards the Coastal Whiptails appear able to drop their tails to distract predators and regenerate new ones.

The signs of a new tail

The signs of a new tail – a difference in taper and scale type

The fellow above appears to have lost its tail and be in the process of growing a new one.  The tail is much shorter than I would expect for a lizard of that size, the tail appears shortened and slightly blunt, and both the scales and coloration are very different from elsewhere on the lizard’s body.

These lizards are extremely wary, crossing open ground at high speed and fleeing when you get too close.  They have a habit of running to cover, then freezing and watching you closely, almost suspiciously.

A suspicious whiptail watches me from cover

A suspicious whiptail watches me from cover

The whiptails are far from the only lizards in the area.  Fence lizards search for high points from which to display and guard their territory:

Fence Lizard showing the blue throat patch

Fence Lizard showing its blue throat patch

Side-Blotch Lizards scurry about:

Side Blotch Lizard keeping an eye on me

Side Blotch Lizard keeping an eye on me

And Large Alligator Lizards (another of my favorites) hide in the damper areas:

A quiescent Alligator Lizard rests in my hand

A quiescent Alligator Lizard rests in my hand

There are others as well, but I don’t yet have photos of them.

I find lizards particularly interesting and evocative.  Despite being less closely related to dinosaurs than birds, they conjure that ancient world to mind.

Chaparral Yucca Seeds, and a Guest

My last post was about Chaparral Yucca, which is blooming in the Santa Monica Mountains right now.  A  few days after writing the post I was exploring Red Rocks Park in Topanga.  This park takes its name from the sculpted sandstone outcrops that rise from the Santa Monica Mountains.

Wind and water sculpted sandstone ledges

Wind and water sculpted sandstone ledges

Like most of the Santa Monica Mountains, this is a dry area, but it is relatively low elevation and nestled in a canyon, the bottom of which has an infrequently running stream and some lovely oak and sycamore trees.

The side slopes are home to the usual assortment of coastal chaparral plants, but the relatively low elevation, slightly greater water supply, and marginally cooler temperatures means that the plants are on an ever-so-slightly different flowering cycle.

Down here some of the Chaparral Yucca (Hesperoyucca whipplei) is still blooming, but other plants are well into the seed setting stage.

Chaparral Yucca seed pods slowly ripening

Chaparral Yucca seed pods slowly ripening

Each of the thorn-like stubs on the branches was a flower.  As you can seen a small percent of the flowers survive to form seed pods.  This year, this is a good crop, in other, wetter, years more might make to this stage.

The pods look like the offspring of a pickle and a ping-pong ball.  Green and slightly warty, divided into three chambers and about the size of a comfortable throwing stone.

Chaparral Yucca seed pod close-up

Chaparral Yucca seed pod close-up

As with the flowers, reaching them is a bit tricky because the basal rosette is composed of lance-shaped leaves crowned with needle tips.  Tips that only seem more aggressive and more prone to break off in your legs as the leaves dry in the increasingly hot summer sun.

Gathering these seed pods was an important activity for many of the coastal tribes as the seeds are edible and nutritious, and unlike the flowers and stalk, the dried seeds can be stored for a long time either whole or ground into flour.

At the moment the seeds are not-yet dried, but are still edible and tasty.

Chaparral Yucca seedpod cross-section

Chaparral Yucca seedpod cross-section

The seeds are flat and black or dark brown, and the capsules look very much like iris or lily seed capsules.  When fully ripe and dry the capsule splits open, disgorging the disk-like winged seeds that flutter to the ground in the frequent coastal breeze.

The green portion of the pod is extremely bitter, so it is best to separate the seeds from the pods for consumption.

The remains of the pods can last for several years in the dry climate.  They look a little like small loofahs hanging on to the dessicated flower stalks.

Chaparral Yucca dried seed pod

Chaparral Yucca dried seed pod

Chaparral Yucca grows in exposed areas in defiance of the sun and shallow soils.  This year even these hardy plants have few blooms and many of the other flowering plants here either didn’t bloom or did so quickly and finished quickly.  Despite the harsh conditions of this year, in some of the darker, damper areas a few plants still show their flowers.

In a little gully, well off the trails, I came across several blooming Scarlet Larkspur (Delphinium cardinale) plants.

Scarlet Larkspur (Delphinium cardinale) still blooming in a shady spot

Scarlet Larkspur (Delphinium cardinale) still blooming in a shady spot

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.

Things that Gall – plants and parasites

The word “galling” is particularly evocative.  In its most simple form something that galls is merely annoying or vexing, but the true definition connotes annoyance taken to an extreme level.  The sort of thing that will do you no harm but rankles tremendously; much like being forced to pay taxes to support actions you object to.

For us these annoyances are mental and emotional, for plants these galls are physical but are often merely annoyances for them as well.

Dried oak apple gall  on Scrub oak in California

Dried oak apple gall on Scrub oak in California

Many plants suffer from galls and the galls are so singular in form that they can be reliably used to identify individual parasite species.  A fantastic book on identifying plant galls for the California region is the Field Guide to Plant Galls of California and Other Western States.

Oak trees seem to be particularly susceptible to parasites of all sorts and a common manifestation is the Oak Apple Gall, most often seen as a hard, woody ball dangling from a twig.  These galls are created by the Oak Apple Gall Wasp, a common name for a variety of small wasps that inject their eggs into the midrib of a developing leaf and chemically trick the tree into growing a protective shell for the developing larvae.  Despite appearing woody when dried, this type of gall is actually a modified leaf.  The delicacy of these galls is more easily seen when they are still green.

Fresh Oak Apple Gall - Virginia

Fresh Oak Apple Gall – Virginia

The developing wasps browse on the oak tissue and are often preyed upon or parasitized by other animals, including birds, raccoons, and a whole host of insects, other wasps included.  Some insects use the gall for their own protection, sharing the space with the wasp larvae.

Oak Apple Gall with non-wasp larva inside next to a Twig Gall - California

Oak Apple Gall with non-wasp larva inside next to a Twig Gall – California

Certain Oak Apple Galls, the Iron Galls,  in Europe were collected to make ink.  For 1500 years ink make from the iron gall was the primary source of writing quality ink in the Western Hemisphere.  For anyone interested Evan Lindquest provides detailed instructions on how to make your own iron gall ink.

Like may things we have a long history with there is a great body of mythology and folk-lore that has accumulated around these galls.

Many galls are hard and woody, there is a Twig Gall I sliced in half in the photo above.  It appears to be empty, but a dark brown patch filled with frass (insect excrement) can be seen winding its way though the bloated tissue.

Oak Apple Galls often fall from the tree, but Twig Galls are a more permanent fixture of the tree.

Twig Gall on a scrub oak branch flowering from the tip - California

Twig Gall on a scrub oak branch flowering from the tip – California

Right now the Scrub Oak is blooming along the coastal mountains in Southern California.  The twig galls are uniformly clustered near the tips of the branches, with many of them crowned by small clusters of flowers.  This provides a bit of insight into the formation of these and other galls.

The gall must be grown, and while the living plant cells are constantly dividing, the true growth of a woody plant takes place at the tips of the branches and roots, or at the apical meristem of each limb.  The cells in the apical meristem are undifferentiated,having the potential to become a wide variety of plant organs, much like stem cells in animals.  The parasite, be it a wasp, bacteria, or virus, co-opts these “stem” cells and gives them new instructions.  In a way the galls are akin to a tightly controlled cancer initiated by the parasite organism.

The Twig Galls I was looking at today were insect formed and, as such, the insect needs to escape the protective structure once it is mature.  Many of the galls had little holes in them showing where the little wasps has crawled out.

Exit holes in a Twig Gall - California

Exit holes in a Twig Gall – California

The variation in galls is astounding.  I have seen leaf galls on wild roses that look like tiny sea-urchins dipped in vermillion.  There are galls that not only force the plant to grow a protective structure around it, but that trick the plant into producing nectar to attract ants which in turn protect the growing larvae from predators.  Many are extremely colorful and the shapes are widely varied.

Colorful leaf galls on a Sugar Maple leaf - Vermont

Colorful leaf galls on a Sugar Maple leaf – Vermont

The common theme is that the galls are all formed in developing tissue, leaves, new twigs, flowers, roots, or fruit.

A gall on Shadbush fruit - Vermont

A gall on Shadbush fruit – Vermont

Some of the Ichneumonidae wasps that make so many of the galls we see have developed a biological metallurgy, evolving zinc and manganese coated ovipositors which they use to inject chemicals and hormones into the plants they co-opt.

The specificity and regularity of the galls and the relationships between the plants and the gall formers speaks to a lengthy and complicated evolutionary history.

We pride ourselves (or are horrified by) our newly found ability to genetically manipulate plants and animals.  In truth, we have a long way to go before we catch up to what we often mistakenly call the “humble” insects.