Archive for the ‘Flora’ Category

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Why Beans?

April 18, 2014

If you start investigating Sonoran Desert plants, including trees and shrubs, you’ll find quite a few members of the bean family (Fabaceae) represented.

Palo Verde blossoms

Palo Verde blossoms

That may seem surprising. Why beans? At first glance, your average garden variety green bean plant does not seem especially deserty.

So let’s start with a hidden feature that might be useful in a desert—to deal with poor soil, beans have come up with a clever friendship—they have symbionts, associates, little bacteria that live in nodules, little bumps, in their roots. The beans provide water and sugars to the bacteria, and the bacteria “fix” nitrogen from the soil, turning it into a form the bean plants can use.

And that’s one reason beans are good for you—because of the nitrogen from their little friends, they can make certain essential amino acids, parts of proteins.

Grains like corn or wheat or rice make different amino acids. And it is important for us to eat them together with legumes, another name for beans, to get whole nutrition in one meal. So, for example, we dine on beans and rice, or beans in corn tacos or wheat tortillas, or baked beans with toast, or even a peanut butter sandwich, since peanuts are also a legume.

Humans figured this out a long long time ago, and in fact, they even grew grains and beans together. An essential core of Native American gardens all over North and South America was the trio of beans, corn and squash. The corn provides scaffolding for the beans to climb, and the remains of the bean plants are a source of usable nitrogen for the next year’s corn and squash. To this day, these three continue to play a big role in our gardens, as well as in those huge gardens known as farms.

It turns out that beans also have a bunch of other cool skills for the hot desert—stay tuned!

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Limiting Factors—Cold!

February 4, 2013

If you were in the Sonoran desert in January 2013, you may well have experienced a limiting factor that many people would not expect in a desert: freezing damaging cold.

In many places it dropped into the 20’s or lower at night, for several nights, enough to nip many buds in the bud.

Native plants, which have been through this before, generally survived quite well, but imports, or annual vegetables, either got crisped or completely melted down.

This suggests that planting native species has even more benefits than we usually consider.

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Ocotillos and Verdins

April 23, 2012

This has been a banner year for ocotillos in the Sonoran desert. They started blooming a couple of weeks ago, and have erupted into full orange color. That’s Fouquieria splendens, for all you science types!

Their nectar attracts a variety of insects, making them a favored landing spot for the small olive yellow birds, the verdins (Auriparus flaviceps.) Look for verdins visiting all kinds of flowering plants throughout the summer and fall.

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Spring Planting

March 8, 2012

Read the rest of this entry ?

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Haboob, the Desert Dust Storm

July 8, 2011

Another limiting factor in the desert arises from the ferocious dessicating and abrasive desert dust storm called the Haboob. Often associated with the seasonal monsoons, these storms can actually happen any time of year, blasting and scouring any plants and animals in their path.

The word haboob is Arabic, from the home of truly impressive sandstorms, but now is applied in any area susceptible to them.

These storms can move particles of dust and even sand, and may reach hurricane force for a few minutes at a time.

Deserts have few trees to stop the wind, and little moisture to hold down the soil. A haboob forms when warm air rises into thunderheads, then the air is cooled by rain, the storm collapses, and the cooled air falls and rushes out from the base of the storm, driving dust and sand before it, sometimes at truly remarkable speeds. Within minutes, winds can go from zero to 50 miles an hour.

Dust storms often arise suddenly, making them hard to avoid or escape. Most years in the Sonoran desert, there are traffic accidents associated with dust storms, when visibility suddenly plummets.

Desert plants need either shelter or thick skins to handle the dessication and scouring associated with a haboob or other winds.

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A Dry Heat

June 29, 2011

The joke is, in the Sonoran desert, even though it’s 114, it’s a dry heat.

The idea being that with very low humidity, amazingly, under 5 percent at times, the heat is easier to bear.

114, an average high for a few days each summer, is still bad enough, but given how few trees and other shelter there is in the desert, it’s almost always a sunny heat during the daytime, which adds another 7 to 10 degrees.

All plants and animals and people that live in the desert need to be built or adapt in some way to survive these extreme temperatures.

The hottest time of year is a few days before the summer Solstice on June 21, and a few weeks after that. Then the average daily temperature starts going down again, very very gradually.

A few weeks after the solstice is also the time when the summer monsoons really get going. The standard definition of monsoon season is the change in the wind, but in the desert, the important thing is that the monsoon usually brings moisture and finally rain from the Gulf of California and the Gulf of Mexico.

And of course, when the humidity goes up and the rains start, it’s still over 100 degrees in the desert. And it’s no longer a dry heat.

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Ocotillos in bloom

April 11, 2011

It is mid-April and the ocotillos are in bloom in the Sonoran desert, a great sight to see.

These plants can leaf out several times a year after rains, but they only bloom once a year, the blossoms providing food for a variety of insects and birds.