Monday, March 9, 2015

Have a peach, have a plum, have a stick of chewing gum

This is the time of year when the stone fruits—the peaches and plums and apricots and almonds—are in full flower. The various shades of pink and white petals, some with splashes of burgundy, are brightening many a back yard with the promise of sweet fruit—or sweet seeds, in the case of almonds—that will mature anywhere from June through August.

They’re not as commonly grown in the lower desert cities as they are in more rural areas at slightly higher elevations, mainly because of their lack of the proper city-fied look and the overbearing watchfulness of the local HOA, I suppose. But from a purely horticultural (and apolitical) point of view, they will grow all the way down into the 1000-2000 feet elevation zones or lower. Why? Because they are considered “low chill” fruits, meaning they don’t need to experience an excessive number of cumulative hours below 45 degrees, sometimes as little as 500, to break dormancy. By contrast, other familiar fruits like the more cold-loving cherries and most apples and pears need 700-1000 chilling hours.   There are two low chill apples, however, that like it hot, namely the cultivars ‘Anna’ and ‘Golden Dorsett’. And, as you might suspect, they flower about the same time as the stone fruits. Ditto for ornamental pears, though they don’t produce a fruit worth eating.

Schnepp’s Farm in Queen Creek is at 1400 feet elevation and it produces a boat load of peaches every year. If they can do it, so can most other areas in the Phoenix metro area, and certainly in Tucson, which is the same elevation as the Arboretum.

The biggest issue for all of these early flowering trees is the danger of frost, which, of course, is more of a hazard at higher elevations than lower. Last year, for instance, there wasn’t a single plum on the Arboretum’s ‘Santa Rosa’ plum across from the Herb Garden (an area where cold air is known to pool), nor was there nary a purple fruit to form on my ‘Santa Rosa’ plum tree at 1000 feet higher in Globe. This year—as of this writing—the prognosis for warm March nights signals a promising harvest, but ya never know.

The common edible fig, Ficus carica, has one of the lowest chilling requirements of any of the commonly grown tree fruits, with just 100-200 chilling hours needed. The same goes for pomegranates. The quince is also a low chiller, but who the heck eats those? Citrus goes without saying; its chilling hours requirement is a big fat zero.

The photos below were all taken this year, mainly at the Arboretum, and show the subtle differences between the flowers of many of the fruits that I just discussed. Because they all flower before they leaf out, it’s hard to tell which tree is which during the flowering period. Just going through the exercise of photographing them has helped me to better ID them by their flowers, particularly from afar. From up close, the bark types show fine, but distinctive characteristics if you stare at them long enough.  After the leaves come out and the fruit begins to attain some size, well, by then, it’s a no brainer.

Kim Stone

Almond 'All-in-One'

Apple 'Anna'

Apricot 'Loring'

Ornamental plum

Peach 'Early Elberta'

Ornamental pear 'Aristocrat'

Plum 'Santa Rosa'

Saturday, February 7, 2015

A tale of a tail

Years ago, I’m not sure when, I accidentally broke off the tail of a gecko. I stepped on the tip of its tail and it broke of quickly and cleanly without a spot of blood. The gecko scampered off a bit lighter, while its severed body part remained behind, gyrating as if in the midst of a seizure. I stood there mesmerized and watched as this autonomous body part behaved like it was receiving rapid fire electronic shocks, which, in a way, it was.

Photo: TStone
For the first two minutes, the swishing  of the tail was spasmodic and continued on one side then the other, flipping over upside down again and again from the momentum. The action was not unlike how a caterpillar reacts when being attacked by ants, or a game fish flexes while fighting the ever-shortening line that leads to the bass boat. The tip of the tail curled far up one side and then the other, jerking rapidly with yoga-like dexterity.

By the third minute, the frantic gyrations were noticeably farther apart in frequency, slowing gradually and evenly. After another five minutes, the tail was still moving, but lethargically now, with longer pauses between movements. It would stop for a two or three seconds, then regain some strength and move quickly again a half dozen times, then stop and eventually start again with an even longer period between movements. After nine minutes, the movement was still active enough for me to keep counting the minutes on my watch, but my interest was waning.

By the eleven minute mark, there was barely any movement except for the very tip of the tail, twitching like a cat's as it contemplates a pounce. At a dozen minutes, it was a boxer in the final round, throwing drunk punches and stumbling from fatigue. By fourteen minutes, it was still moving but with five or more seconds between each twitch. The thicker end (the broken end) that hadn’t moved much was now making some subtle, noticeable movements, but the opposite tip had all but stilled. At the fifteen minute mark, there were a long seven or eight seconds between pulses. At this point, I started thinking more about what I had brought for lunch than indulging my scientific curiosity.

From the gecko's point of view, I acted exactly the way that was intended: I was so distracted by this disconnected flailing body part that the far more important half with the brain, legs, vital organs, and reproductive potential was able to make a successful getaway. And that, it did.

Kim Stone

Friday, January 23, 2015

Original Face and the Ancient Seas

     Superior, Arizona, just a couple of miles east of the BTA, sits at the base of a geological formation known locally as Apache Leap. The cliffs of the Leap are composed of a dark volcanic tuff squeezed from the earth’s bowels around 25 million years ago.  In the hills beneath the cliffs, one sees layered bands of gray sedimentary rock – once a seabed but now faulted limestone – having originated during the Carboniferous Period. In this limestone, one finds the remnants of organisms that populated the ancient seas – mostly brachiopods, bivalves, and crinoids. 

     My partner Lori and I hiked up to study a few of those limestone outcroppings. We found a slab about 30’ long and 8’ high, composed mostly of a dense conglomeration of fossilized shells. We walked along that wall, brushing our hands thoughtfully across a solidified expanse of time.

     For me, fossils demand some reflection. Their antiquity – 300 million years in the case of these shells – is enough to warrant a few minutes of awe-struck wonder. When these marine creatures were alive, there were dense forests of trees and ferns that eventually became the coal deposits on which much of industrialized mankind depend. There were also insects back then, and fish, and millipedes six feet long. These bivalves and brachiopods were also alive when the most “advanced” land animal was a type of amphibian. Even if the bivalves had had our consciousness (which, of course, they did not), they could still not have imagined that their forms would be covered in mud, replaced by minerals, buried beneath the roiling earth, and then pushed back up and uncovered, only to be marveled over by a species of primate. Beside this cracked gray monolith of shells, I was reminded of the Zen koan, “What was your face before your parents were born?”

      There is a twisting string that goes back, long before these marine animals existed, connecting us all by chemical alignments allowing seemingly infinite variation. This three and a half billion-year-old string has frayed, with minute strands bending in different directions and many strands being cut entirely by catastrophic events, but here we are, barely standing, with binocular vision and swiveling heads and brains containing 86 billion neurons, studying a wide and uneven terrain. I touched the ancient fossil shells and realized I was also touching a part of a shared lineage to all living things.  I was, in a sense, seeing my original face.  

     Wistfully I wondered: How can the abstract and poetic latitudes of our thoughts ever be preserved in the turbulent pressures of time? I don’t think papyrus or a thumb drive will last as long as these shell fragments. My consolation was that, momentarily, for whatever it was worth, I could ease myself against a relic of earth’s biological and geological magnitude and not feel intimidated. 

- T. Stone

Tuesday, January 20, 2015

Geology Tourguide and ASU Professor Steve Semken

Why is our "Rocks of BTA" walk so enduringly popular? Even during the hottest summer months this geology tour consistently draws dozens of enthused attendees. One of our charming rock-jock tour guides may have said it best a few years back when interviewed: "Deep down we all know that geology is the most exciting subject on this planet—and  perhaps all planets. Anyone with a basic understanding geology can look at any mountain that surrounds them and begin to understand the true diversity of nature and depth of time."

Then again, our charismatic guides are a draw: adventurous ASU Professor Steve Semken, plus two professional geologists, Scott McFadden and Rich Leveille. Tempe resident Steve Semken teaches geology and sustainability science and has been a professor at ASU since 2003. Geologic research has taken him around the world from New England to Inner Mongolia. We caught up with this globe-trotting geologist who says most of his most enthralling rocks and landscapes are right here in Arizona. He's a volunteer with the AZ State Parks system, guiding geology walks at Boyce Thompson Arboretum (check the updated schedule at  and included with $10 park admission.

Q. Why is Arizona a great place to be in your line of work?
The one-word answer is exposure. Our arid climate means that a lot of Earth’s crust is visible at the surface and easier to study! But what really makes Arizona unique is its magnificent diversity of landscapes, rocks, and ecosystems. It’s kind of like three states in one: northern Arizona and southern Arizona have very different topography and exposed rocks, as do the rugged central highlands lying in between. The Superior area, including the Arboretum, is especially interesting because it is located at the boundary between two of these major topographic regions, so there’s a lot of variation in a short stretch.

Q. Did you collect rocks when you were a kid?
Yes, from early on. I was born and reared in northern New Jersey. New Jersey has amazing geology, but most of it is covered up by vegetation or civilization! Luckily for me, my parents bought me a membership to a rock and mineral club, and I was able to take many memorable field trips and hikes into places where you could actually see and collect rocks, such as the Franklin mining district, which is world-famous. Many people don’t know that New Jersey was a hard-rock mining state for much of its history…it provided iron for George Washington’s army. Another key thing my parents did for me was to give me a big illustrated Golden Book of Geology, not long after I learned to read. That book made a huge impression on me, and I still have it on my office bookshelf.

Q. What's the focus of your research at ASU?
My primary field is called ethnogeology. It’s a new specialty that combines geology, geography, and anthropology. My students and I are very interested in learning how different cultures understand and interact with the Earth in their homelands. That research goes back to my previous job, teaching geology at the tribal college of the Navajo Nation. My students and I work mostly in the Southwest but also in some parts of Latin America.

One of our major goals is to use our findings to help encourage more diverse students to pursue careers in geology. Another is to use different perspectives to promote more sustainable living in our desert environment.
I also do geologic research in the field in northern and central Arizona with my students. You might be surprised to know how much more we still have to learn about the geologic history of our home state. I never get tired of teaching about southwestern geology.

Q. What are a few hobbies or interests outside of geology ?
Hmm…it’s kind of hard for me to separate work from hobby because most of my pastimes involve being outdoors in the deserts or mountains.  And one of the perks of being a field geologist is getting paid to work outdoors in beautiful places! But I’m particularly fond of river rafting, camping, and hiking with my wonderful wife jeanne and our dog Sancho. BTA is a favorite place for the 3 of us to go. I don’t turn the geologist part of me off when I’m out on a hike or rafting a river for fun, and I appreciate jeanne’s forbearance (and interest) when I get a little nerdy at a rock outcrop now and then.  Some of my other passions are cooking, wines, tequilas, and Sun Devil football.

Q. What are two charismatic rocks you point out on Arboretum tours?
All rocks are interesting to geologists because they tell stories about the Earth. I’d say the coolest rocks are the ones that are “in your face” with their stories—they have features that people can readily see and interpret. Among my favorites are the big freestanding blocks of grey schist near the Smith Building.  Schist is a crystalline rock that forms deep in the crust and records the very origins of continents and mountains. You can see grey schist exposed as you drive through Gonzales Pass west of the Arboretum. That rock tells the story of the original formation of Arizona’s deep crust, about 1800 million years ago.

But I think the coolest rock of all at BTA is the volcanic breccia exposed in the bed of Silver King Wash where the Chihuahuan Desert Trail crosses. Breccia is made up of big chunks of rock expelled by a volcano and welded together. The breccia in Silver King Wash has fist-sized chunks of white pumice set in a matrix of tan volcanic ash. Rock like that is direct evidence of the violent volcanic eruptions that occurred locally about 20 to 18 million years ago and also formed the Superstition Mountains and Picket Post Mountain. I always end my geology hikes at that spot in the wash.