May 26, 2009
May 20, 2009
Spring into Summer
As I watched kids piling into school the other day wearing shorts, sneakers and t-shirts, I had to grudgingly admit that it is beginning to look like summer. A Saturday stop at the Pasadena Farmer’s Market made that even clearer. No, it wasn’t the shoppers in flip flops who convinced me. It was the displays of artichokes, strawberries and cherries showing off their summer color. The smell and intense color of rainier cherries sends out an almost hypnotic call which local shoppers can’t resist. The season for them is short, a mere five weeks, so now is the time to get cherry wild. There were also collections of early dug potatoes, some no larger than a walnut, with colors from white to red to brown to purple ready to be boiled in salt water and drizzled with butter. One farmer had displays of colorful radishes, even elongated pink and white French breakfast radishes, right next to multihued beets all sharing space with big, sugary sweet onions with gigantic green tops banded together. Farmer’s markets can inspire your inner chef and looking at those onions, my inner chef was whispering ‘onion rings’. There were crates of small blushy apricots and a farm helper was cutting up a few and handing out samples. His stand was a few feet away from another farmer selling vegetable and herb starts; small fingers of rosemary to plant, tomato seedlings of all kinds and big buckets of mint for $3 which, once planted, are sure to keep you in tabouleh all summer long.
Toward the market entrance was a flat bed truck piled high with avocados for sale. Almost all were the black pebbly Haas variety with a bag of four selling for $1.50. That’s pretty cheap, especially by farmer market standards. Avocados start to mature in spring and by now the trees are loaded with ripe fruit which must be picked and eaten. How lucky we are.
While we add avocados to salads for dinner, mash and spoon them on top of whole wheat toast for breakfast or into veggie sandwiches, nothing compares with our deep desire to turn them into guacamole. At my house, the spicy, smooth, limey flavor of guacamole keeps everyone reaching for another tortilla chip until the bowl is scraped clean. I expect that we’re not unusual. People have been making guacamole since Aztec times, only the original Aztec recipe was a stripped down combination of avocados, tomato and salt. In fact, the word ‘guacamole’ is compound word of Aztec origin. In native Nahuatl, the word “ahuacatl” means avocado and “molli” means sauce.
There are as many recipes for guacamole as there are passionate guacamole eaters, which is to say, a lot. As a general rule of thumb, avocados should be the main ingredient. From there, anything goes. Add jalapenos, hot sauce, onions, garlic, tomatoes, cilantro, lime juice, whatever else you like, and you have a great dip to share or to hoard entirely to yourself.
It’s not a hard dish to make. To prove it our Kindergarten through 8th graders will be whipping up batches of guacamole all next week. Contact your child’s teacher and find out when the festivities will begin and plan a ‘surprise’ visit. You’ll be delighted at what you see and what you taste.
Toward the market entrance was a flat bed truck piled high with avocados for sale. Almost all were the black pebbly Haas variety with a bag of four selling for $1.50. That’s pretty cheap, especially by farmer market standards. Avocados start to mature in spring and by now the trees are loaded with ripe fruit which must be picked and eaten. How lucky we are.
While we add avocados to salads for dinner, mash and spoon them on top of whole wheat toast for breakfast or into veggie sandwiches, nothing compares with our deep desire to turn them into guacamole. At my house, the spicy, smooth, limey flavor of guacamole keeps everyone reaching for another tortilla chip until the bowl is scraped clean. I expect that we’re not unusual. People have been making guacamole since Aztec times, only the original Aztec recipe was a stripped down combination of avocados, tomato and salt. In fact, the word ‘guacamole’ is compound word of Aztec origin. In native Nahuatl, the word “ahuacatl” means avocado and “molli” means sauce.
There are as many recipes for guacamole as there are passionate guacamole eaters, which is to say, a lot. As a general rule of thumb, avocados should be the main ingredient. From there, anything goes. Add jalapenos, hot sauce, onions, garlic, tomatoes, cilantro, lime juice, whatever else you like, and you have a great dip to share or to hoard entirely to yourself.
It’s not a hard dish to make. To prove it our Kindergarten through 8th graders will be whipping up batches of guacamole all next week. Contact your child’s teacher and find out when the festivities will begin and plan a ‘surprise’ visit. You’ll be delighted at what you see and what you taste.
May 12, 2009
Telling Time with Flowers and Bees
Below is a reprint excerpted from a new book called "The Rhythms of Life" which explores the science of chronobiology (i.e. the biology of time). In it the authors, Leon Kreitzman and Russell Foster, detail the timekeeping abilities of flowers and bees. There are some great gardening/teaching ideas here for children.
"Gardeners know that plants open and close their flowers at set times during the day. For example, the flowers of catmint open between 6:00 a.m. and 7:00 a.m.; orange hawkweed follows between 7:00 a.m. and 8:00 a.m.; field marigolds open at 9:00 a.m.
In “Philosophia Botanica” (1751), the great taxonomist Carl Linnaeus proposed that it should be possible to plant a floral clock. He noted that two species of daisy, the hawk’s-beard and the hawkbit, opened and closed at their respective times within about a half-hour each day. He suggested planting these daisies along with St. John’s Wort, marigolds, water-lilies and other species in a circle. The rhythmic opening and closing of the plants would be the effective hands of this clock.Plants have carefully timed routines determined by internally generated rhythms. In 1729, Jean-Jacques d’Ortous de Mairan, a French astronomer, put a Mimosa plant in a cupboard to see what happened when it was kept in the dark. He peeked in at various times, and although the plant was permanently in the dark its leaves still opened and closed rhythmically – it was as though it had its own representation of day and night. The plant’s leaves still drooped during its subjective night and stiffened up during its subjective day. Furthermore, all the leaves moved at the same time. It took another 230 years or so to come up with the term circadian – about a day – to describe these rhythms.
In a similar vein, tobacco plants, stocks and evening primroses release their scent as the sun starts to go down at dusk. These plants attract pollinating moths and night-flying insects. The plants tend to be white or pale. Color vision is difficult under low light, and white best reflects the mainly bluish tinge of evening light.
But plants cannot release their scent in a timely manner simply in response to an environmental cue, like the lowering of the light levels. They need time to produce the oils. To coincide with the appearance of the nocturnal insects, the plant has to anticipate the sunset and produce the scent on a circadian schedule.
Flowers of a given species all produce nectar at about the same time each day, as this increases the chances of cross-pollination. The trick works because pollinators, which in most cases means the honeybee, concentrate foraging on a particular species into a narrow time-window. In effect the honeybee has a daily diary that can include as many as nine appointments — say, 10:00 a.m., lilac; 11:30 a.m., peonies; and so on. The bees’ time-keeping is accurate to about 20 minutes.
The bee can do this because, like the plants and just about every living creature, it has a circadian clock that is reset daily to run in time with the solar cycle. The bee can effectively consult this clock and “check” off the given time and associate this with a particular event.
Honeybees really are nature’s little treasures. They are a centimeter or so long, their brains are tiny, and a small set of simple rules can explain the sophisticated social behavior that produces the coordinated activity of a hive. They live by sets of instructions that are familiar to computer programmers as subroutines – do this until the stop code, then into the next subroutine, and so on.
These humble little bees have an innate ability to work out the location of a food source from its position in relation to the sun. They do this even on cloudy days by reading the pattern of the polarization of the light, and pass this information to other bees. In the dark of the hive, they transpose the location of a food source in the horizontal plane through the famous “waggle” dance into communication in the vertical plane of the hive.
Honeybees can tell their sisters how far away the food is up to a distance of about 15 kilometers. For good measure, they can also allow for the fact that the sun moves relative to the hive by about 15 degrees an hour and correct for this when they pass on the information. In other words, they have their own built-in global positioning system and a language that enables them to refer to objects and events that are distant in space or time.
German scientists in the early part of the last century called this ability of bees to learn the time of day when flowers start secreting nectar and visit the flowers at appropriate times Zeitgedächtnis, or time-sense. But the species of flowers in bloom, say, this week, is likely to be replaced by a different species at a different location next week or the week after. The bee needs a flexible, dynamic appointments system that it continually updates, and it has evolved an impressive ability to learn colors, odors, shapes and routes, within a time frame, quickly and accurately.
While the initial dance by a returning scout bee informs her sisters of the location and distance of food plants and the quality of their nectar, bees that visit the food source learn to synchronize their behavior with daily floral rhythms, foraging only when nectar and pollen are at their highest levels. At other times, they remain in the hive, conserving energy that otherwise would be exhausted on non-productive foraging flights.
Although most animals, including humans, cannot sustain long-lasting periods of activity without circadian rhythms, honeybees have developed a marked flexibility in their circadian rhythm that depends on the job they are doing. Whereas a particular circadian determined behavior is usually fixed to a certain phase of the cycle, in honeybees the circadian rhythm is dependent on the job the bee is doing.
Adult worker bees perform a number of tasks in the hive when they are young, like caring for eggs and larvae, and then shift to foraging for nectar and pollen as they age. However, if the hive has a shortage of foragers, some of the young nurse bees will switch jobs and become foragers. The job transition, whether triggered by age or social cues, involves changes in genes in the honeybee brain; some genes turn on, while others turn off.
"Gardeners know that plants open and close their flowers at set times during the day. For example, the flowers of catmint open between 6:00 a.m. and 7:00 a.m.; orange hawkweed follows between 7:00 a.m. and 8:00 a.m.; field marigolds open at 9:00 a.m.
In “Philosophia Botanica” (1751), the great taxonomist Carl Linnaeus proposed that it should be possible to plant a floral clock. He noted that two species of daisy, the hawk’s-beard and the hawkbit, opened and closed at their respective times within about a half-hour each day. He suggested planting these daisies along with St. John’s Wort, marigolds, water-lilies and other species in a circle. The rhythmic opening and closing of the plants would be the effective hands of this clock.Plants have carefully timed routines determined by internally generated rhythms. In 1729, Jean-Jacques d’Ortous de Mairan, a French astronomer, put a Mimosa plant in a cupboard to see what happened when it was kept in the dark. He peeked in at various times, and although the plant was permanently in the dark its leaves still opened and closed rhythmically – it was as though it had its own representation of day and night. The plant’s leaves still drooped during its subjective night and stiffened up during its subjective day. Furthermore, all the leaves moved at the same time. It took another 230 years or so to come up with the term circadian – about a day – to describe these rhythms.
In a similar vein, tobacco plants, stocks and evening primroses release their scent as the sun starts to go down at dusk. These plants attract pollinating moths and night-flying insects. The plants tend to be white or pale. Color vision is difficult under low light, and white best reflects the mainly bluish tinge of evening light.
But plants cannot release their scent in a timely manner simply in response to an environmental cue, like the lowering of the light levels. They need time to produce the oils. To coincide with the appearance of the nocturnal insects, the plant has to anticipate the sunset and produce the scent on a circadian schedule.
Flowers of a given species all produce nectar at about the same time each day, as this increases the chances of cross-pollination. The trick works because pollinators, which in most cases means the honeybee, concentrate foraging on a particular species into a narrow time-window. In effect the honeybee has a daily diary that can include as many as nine appointments — say, 10:00 a.m., lilac; 11:30 a.m., peonies; and so on. The bees’ time-keeping is accurate to about 20 minutes.
The bee can do this because, like the plants and just about every living creature, it has a circadian clock that is reset daily to run in time with the solar cycle. The bee can effectively consult this clock and “check” off the given time and associate this with a particular event.
Honeybees really are nature’s little treasures. They are a centimeter or so long, their brains are tiny, and a small set of simple rules can explain the sophisticated social behavior that produces the coordinated activity of a hive. They live by sets of instructions that are familiar to computer programmers as subroutines – do this until the stop code, then into the next subroutine, and so on.
These humble little bees have an innate ability to work out the location of a food source from its position in relation to the sun. They do this even on cloudy days by reading the pattern of the polarization of the light, and pass this information to other bees. In the dark of the hive, they transpose the location of a food source in the horizontal plane through the famous “waggle” dance into communication in the vertical plane of the hive.
Honeybees can tell their sisters how far away the food is up to a distance of about 15 kilometers. For good measure, they can also allow for the fact that the sun moves relative to the hive by about 15 degrees an hour and correct for this when they pass on the information. In other words, they have their own built-in global positioning system and a language that enables them to refer to objects and events that are distant in space or time.
German scientists in the early part of the last century called this ability of bees to learn the time of day when flowers start secreting nectar and visit the flowers at appropriate times Zeitgedächtnis, or time-sense. But the species of flowers in bloom, say, this week, is likely to be replaced by a different species at a different location next week or the week after. The bee needs a flexible, dynamic appointments system that it continually updates, and it has evolved an impressive ability to learn colors, odors, shapes and routes, within a time frame, quickly and accurately.
While the initial dance by a returning scout bee informs her sisters of the location and distance of food plants and the quality of their nectar, bees that visit the food source learn to synchronize their behavior with daily floral rhythms, foraging only when nectar and pollen are at their highest levels. At other times, they remain in the hive, conserving energy that otherwise would be exhausted on non-productive foraging flights.
Although most animals, including humans, cannot sustain long-lasting periods of activity without circadian rhythms, honeybees have developed a marked flexibility in their circadian rhythm that depends on the job they are doing. Whereas a particular circadian determined behavior is usually fixed to a certain phase of the cycle, in honeybees the circadian rhythm is dependent on the job the bee is doing.
Adult worker bees perform a number of tasks in the hive when they are young, like caring for eggs and larvae, and then shift to foraging for nectar and pollen as they age. However, if the hive has a shortage of foragers, some of the young nurse bees will switch jobs and become foragers. The job transition, whether triggered by age or social cues, involves changes in genes in the honeybee brain; some genes turn on, while others turn off.
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