Saturday, July 30, 2011

July in the Sonoran Desert

It is this time of year that the desert waits for the violent monsoon rains.  So far the storms have been hit or miss and much of the desert has not received any significant rainfall.  As is typical, higher elevations are more likely to receive rain than the lower and hotter elevations.  And eastern portions of the Sonoran Desert, such as around Tucson, are far more likely to receive rain than western portions, such as around Yuma. The end of June through mid-July are unbearably hot, highs over 110 degrees are quite common.  Rain has been absent from the desert for months on end, and the desert life hides from the relentless heat and sun.  Life simply dries up or congregates around waterholes this time of year.  Everything becomes sluggish except for the Saguaro fruit ripening which livens things up for a few weeks.  But as Saguaro harvest wains so does activity of nearly all desert life.  The desert simply waits and longs for cooling life giving rain.
An Anvil Cloud that often proceeds a Monsoonal thunderstorm.  An Anvil Cloud is a type of cumulus cloud.
Even though the rains have not come that does not mean the violence of these storms has not come to the desert.  As is typical of the desert, the rain comes with a lot of hype.  Often these monsoonal storms are proceeded by humidity, gigantic anvil clouds, dark stormy clouds, wind, clouds that are raining but rain never hitting the ground, dust storms, and sometimes if we're lucky rain.  This whole process can be quite disappointing to desert dwellers to say the least.  Too often these storms simply end in just a lot of dust, wind, and no rain.  This disappointing end does provide some relief however.  Even in the absence of rain clouds shade some of the suns scorching rays and the rain that never hits the ground still cools the air considerably in some cases.  Humidity that proceeds monsoons can also drop the temperatures five to ten degrees for weeks ahead of the first rains.  In the Sonoran Desert if its not the 110 degree dry heat, its the 105 degree humid heat, you decide what is worse...
Haboob dust storm in Phoenix, Arizona.  Picture from Wikipedia.
Dust storms in the Sonoran Desert are quite the interesting phenomena.  These are not sand storms like in the Sahara Desert, they are actually clay particles picked up and blown around by the wind.  The reason for this is that clay is the smallest dust particle and is easiest to be picked up off a dry landscape and blown around.  The technical name for these "clay storms" are haboobs.  Yes, this is an awkward weird word but it is Arabic, so of course it won't seem normal to English speakers.

Haboobs are very important soil formation events.  All of the dust and clay within these dust storms has to fall on soil somewhere.  Dusts from these storms is deposited on soils and enriches them with magnesium, calcium, iron, and of course clay.  After these things are deposited on soil surfaces, rain water will carry them deeper into the soil.  After thousands of years of this happening iron stains the soil red, magnesium stains rocks on the surface black, calcium forms a rock-like layer called caliche about 2-3 feet deep, and clay forms a dense clay-rich horizon just above the caliche called an argillic (Click here for more info from an prior blog entry).  Caliche and argillic soils are extremely important in determining what types of plants live in a particular locations.  Some plants prefer soils with caliche or argillics while others do not.  More on that another time though.

The rains should come to nearly the whole Sonoran Desert within the next few weeks or so.  That is, at least the eastern portion.  Normally Tucson receives about six inches of rain, Phoenix three, and Yuma less than one during Monsoon season.  But actually amounts vary from year to year.  In Phoenix I have seen years with only a half inch or so, and other years with nine inches.  It has been a few years since we have had a really good amount of rain during Monsoons season, maybe that means this will be a good one!

Friday, July 29, 2011

Eastern deciduous forest dry uplands

A late successional mature dry Eastern Deciduous Forest composed primarily of White Oaks.

The third type of Eastern Deciduous Forest is the dry, or xeric, forest.  These forests are often on hills adjacent to rivers and have sandy dry soils.  Standing on one of these hills, which can be quite large, you might be surprised to know that millenniums ago the hill was actually in the river!  That is, the sandy sediments in and along the river were blown on shore forming sand dunes.  These sandy wind deposited soils, called loess, stabilized when vegetation was established and eventually formed prairies or forests similar to what we see today in the Midwest.  So many millenniums ago the sandy hills that line rivers simply wouldn't have been there.  They would have instead been sandy sediments along the riverbed awaiting winds to blow them away and deposit them as dunes that would eventually turn into hills.  This is not always the case for xeric woodlands but is very often the case.

A loess hill Tall Grass Prairie, Oak Savanna near Cedar Rapids.  This Loess hill is adjacent to the Cedar River floodplain.  It has extremely sandy soil which once resided in the Cedar River until it was blown away and deposited as this hill.  The Red and Bur Oak trees in this savanna are adapted to prairie fires, the dry soil conditions, and are therefore important early successional trees in this type of environment.  A savannah, in the absence of fire, is a type of early successional forest.
One way you can identify loess deposits is to look for sandy soils, especially on hills, that are adjacent to rivers.  The sandy soils are course or gritty feeling and typically light in color, indicating low organic content.  Also, the absence of rocks and bedrock may indicate loess.  These sandy soils drain water rapidly and are warmer, therefore making them dry.  All plants that colonize these areas therefore must be well adapted to dry Midwestern conditions.  While nothing compared to desert conditions, some desert species such as yuccas and prickly pear cacti can on occasion be found here.  And being grasses generally favor drier conditions than trees, prairies often favor these sandy sites.  Red, Bur, and White Oak trees are also well adapted to these dry conditions and will often colonize these areas forming savannas, which is an early successional stage of xeric forests.  These oak species are well adapted to prairie fires, therefore allowing them to survive surrounded by prairie.  Sumac and Red Cedar are also important colonizing or early succession forest species, but these can only grow in the absence of fire.  Oaks and Cedars are very long lived and tough trees.  Cedars have the remarkable ability to grow just about anywhere including out of cracks in rocks.  Typically early successional trees do not survive into later more mature forests but both Oaks and Cedars can survive hundreds of years, seeing a forest from first establishment all the way through late successional maturity.
Oak, Hickory, and Ironwood xeric forest near Cedar Rapids, Iowa.
Typically, once Oaks are established more shade tolerant trees will start to colonize the area.  Hickory trees are one of the more common large trees that come along later in xeric forests.  Ironwood are a common understory tree with dogwoods as a common shrub layer.  With all the acorns and Hickory nuts within these forests they are popular places for squirrels, deer, and turkey.  There are also a lot of fruits present in the dry forests.  Wild Black Cherries seem to have a preference for these sandy soils.  Tree diversity is less in xeric forests when compared to mesic forests and as a result there is less bird diversity, but birds and other animals are abundant none-the-less.  As for bird watching though I typically stick to more mesic forests, but for admiring majestic Oaks and Hickory trees that are hundreds of years old I'll go for the xeric forests.
Old mature White, Red, and Bur Oaks growing in a dry deciduous forest.

Thursday, July 28, 2011

Albuquerque Rio Grande Botanical Garden and Aquarium

I recently made a quick trip through Albuquerque and was privileged enough to stop by the Albuquerque New Mexico Rio Grande Botanical Garden and Aquarium (click here for website).  The Aquarium is on the smaller size but has a number of great tanks.  The shark tank was quite impressive and I enjoyed their native fish displays.  I also enjoyed botanical garden, especially the Rio Grande Heritage Farm with their livestock, large gardens, flowers, and orchard.  The orchard was especially impressive to me.  Anyway here are some pictures of the aquarium and garden, well worth a visit is you live in the area or are passing through.  This is an absolutely wonderful place to learn all kinds of things about plants, animals, fish, and farming. 

Prickly Pear Cactus flower

Apache Trout

Purple Cone Flower


Butterfly garden

Lily pad

Rio Grande Heritage Farm

Rio Grande Heritage Farm

Eastern deciduous forest mesic uplands

A mesic deciduous forest in North Eastern Iowa along Twin Springs Creek near Decorah.  This Mesic forest is dominated by Maple, Basswood, and some Elm, Hackberry, and White Pine.  
Upslope from the bottomland forests we talked about in our last blog entry we walk into what is known as a mesic forest.  Mesic is simply a scientific term for a soil that holds a well balanced water water supply, not too much and not too little.  Compared to bottomlands this forest is much more hospitable, the ground is less soggy and their are fewer mosquitoes.  Stinging Nettles and Poison Ivy are still present though.  In the spring, this is where you will find an abundance of forest wildflowers.  A lot of the species found in the bottomlands are also found in the mesic uplands.  Ash, Walnut, Elm, Maple, can be found in both up and bottom lands.  However, in the uplands Walnut is more abundant and there is more White and Green Ash then there is Black Ash.  Black and Red Maple are also more abundant than the Silver Maples common to bottomlands.  There also is the addition of Ironwood and Oak species, such as White and Red Oak.  Overall, mesic woodlands often have a greater diversity of trees then the bottomlands.

Early succession mesic deciduous forest composed mostly of Bigtooth Aspens but also a few Sumac trees.
Succession in the upland forest is different then the bottomlands.  Sumac and Bigtooth Aspens are some of the most common trees to first establish a mesic forest, but these trees usually don't live long before they are replaced by other species such as Oaks, Ashes, Maple, Elm, Walnut, or Basswood.  Red, White, and Bur Oaks are also common early successional trees.  These Oaks however live much longer then Sumac and Aspen and are very common in later successional forests.  The oldest mesic forests are often dominated by Maple and Basswood (in Eastern Iowa anyway).  Dogwood, Elm, and Ironwood are very common shrubby or understory trees in both the mid and late successional forest.
A mid successional mesic forest composed mostly of White Oak but with an understory of Maple trees.  There are not any seedling oaks in this forest because the Oaks require more sunlight then is present in this forest.  Maples however are tolerant of shade and will one day replace these Oak trees.
Coming across animals in the uplands is a little more difficult.  This is probably because the uplands are a little easier for people to walk around in without sinking into some sort of mud pit...  Deer are quite common here and squirrels can be everywhere.  And anywhere you find an abundance of Oak trees you will find turkeys.  Turkeys are quite entertaining to watch.  They love mature Oaks for sleeping in and eating the abundance of acorns they produce.  Turkeys are pretty shy birds and if you are lucky enough to watch a few of them they do all kinds of goofy things.  Just the way they walk around seems goofy to me.  As for flying, it seems weird that a bird that size can ever get off the ground.  But despite their goofiness they they are quite beautiful and amazing creatures.  If viewed in the right sunlight they have an almost iridescent bronze feathered body, and the male strutting and gobbling during spring mating season is an amazing show.

Being the uplands have an abundance of fruits they are also home to an abundance of birds.  Choke Cherries, Dogwood berries, Raspberries, Black Cherries, and Goose Berries are just some of the more common fruits produced here.  There is nearly continuous production of one type of fruit after another through out the summer, supplying a continuous food supply to the animals, and especially birds that reside here during the summer.  These fruits are highly adapted to birds and are in-fact designed to have birds eat them.  A fruits generally bright color simply says "eat me!" to any passer-byer (but don't do this unless you absolutely know what the fruit is, there are poisonous brightly colored fruits such as Poison Ivy!!!).  When a bird eats these fruits the seeds pass right through their digestive tract and are deposited elsewhere, thus the bird aids the transportation of the seeds to colonize new locations.

Nuts are also abundant in the upland forest.  Acorns, Walnuts, and Hickory nuts are abundant in the fall, supplying food for animals and birds of all types.  Everyone knows squirrels love nuts, but so do deer, bear, raccoon, chipmunks, and large birds such as woodpeckers, Blue Jay, and Turkey.  These animals often gorge themselves on nuts when they ripen in the fall.  The high fat content of nuts makes them a great food to fatten animals up for winter.  Some of the other common birds to the upland forest are Warblers of all types, Cardinals, Wood Thrush, Indigo Bunting, Fly Catcher, Gnat Catcher, and Rose Breasted Grossbeak.  The best time to see these birds is early in the morning.
Dunning Springs near Decorah, Iowa.  This waterfall is in mesic forest primarily of Maple and Basswood but also Elm, Hackberry, and Ash.

Saturday, July 23, 2011

Eastern deciduous forest bottomlands

Pulpit Rock in the foreground and the Upper Iowa River floodplain and bottomlands in the distance.  Northeastern Iowa near Decorah.
Eastern Deciduous Forest bottomlands can be quite the interesting place to visit.  If you were dropped off in the middle of one of these forests during the summer probably the first thing you would notice would be the mosquitoes.  Secondly, you would notice thick vegetation and in most cases the soggy ground.  Some areas would be dry but most areas would be at least moist, if not so muddy that you could never imagine walking through them.  As you tried to hike out of the forest you would find yourself bushwacking through thickets of stinging nettles and poison ivy.  You would also walk through tall grassy areas or cross over nearly barren ground due to the thick tree canopy above or recent flooding that killed ground vegetation.  

These forests are always quite flat except for depressions where small ponds or drainages form.  This flat structure is a result of decades to centuries of river flooding (or more).  The nearby river is what defines the bottomland forest and makes it a quite inhospitable place.  As any river flows it erodes away soil and deposits it elsewhere, especially during floods.  Typically this eroded soil is deposited where the water slows along the river banks.  Year after year, flooding deposits sediments along the river bank resulting in the formation of a floodplain, which is where bottomland forests are found.  A newly formed floodplain will first be colonized by ragweed and grasses.  If it is stable and isn't washed away by river flooding, Willows will begin to colonize it, often forming quite dense stands.  Cottonwoods will shortly follow.  Very few of these trees will ever reach maturity.
A dense stand of Willow and Cottonwood trees.  The earliest stage of bottomland forest succession.  These trees require full sunlight to grow.
If the area is heavily disturbed by flooding year after year the stand of Willows and Cottonwoods may persist.  But if the area is slightly drier and not as strongly disturbed for many years other trees may move in like Ash, Elm, Swamp Oak, Walnut, or Basswood.  If the floodplain remains stable even longer, many decades after these trees are established Maple trees will become the dominate tree.  This progression of tree species is called succession.
Not the greatest picture but shows a dense thicket of Maple trees (left half of photo) growing under the canopy of more mature Ash trees (the larger stump on the right).  Most of these Maple trees will die, but due to their ability to grow in shade, the Maples will one day replace the Ash trees.  One day this Ash tree forest will be a Maple forest.  This is an intermediate stage of Bottomland Forest succession.  This bottomland is located adjacent to the Cedar River in the Wikkiup Hill Natural Area in Eastern Iowa.

A Bottomland Eastern Deciduous Forest composed almost exclusively of Silver Maple with a few Elm, Sugar Maple, and Cottonwood trees.  This is nearly the latest stage of bottomland forest succession.  This bottomland is also at Wikkiup Hill Natural Area in Eastern Iowa.
As you can probably tell from the description, the Bottomland Forest is not somewhere you would want to pitch a tent and camp out for the night due to its in-hospitable nature.  However, this wild in-hospitality is what makes it so interesting and exciting to explore.  Exploring it with a good amount of bug spray, some waterproof boots, a hiking trail, and the ability to identify Poison Ivy and Stinging Nettles makes these areas more accessible.  Not many people brave the mud and bugs of bottomlands so they become tremendous wildlife refuges.  Deer, Turkey, Raccoons, beaver, otters, muskrat, ducks, and a whole host of birds are in abundance in bottomlands.  On recent hiking trips I saw several Whitetail Deer fawns in bottomlands and absolutely none in drier more hospitable upland forests.  
An ephemeral pond in a Bottomland Forest left over after flooding.  Ephemeral ponds are temporary in nature, forming in spring with flooding and drying out later in the summer.  These ponds are home to a wide variety of organisms including, salamanders, frogs, toads, and ducks.  Picture is from Cedar River floodplain located at the Indian Creek Nature Center in Eastern Iowa.
Based on the above description of the bottomlands you can probably tell that these areas form quite diverse habitats.  Annual flooding disturbs some areas more then others and makes some areas wetter then others.  This creates a variety of different forest types in differing stages of succession and a variety is different water habitats.  All kinds of interesting animals can be found in their preferred habitat type (also called a niche) and the greater diversity of habitats, the greater diversity of organisms you will find.  Yet another great reason to explore the bottomlands.  

Friday, July 22, 2011

Soil Color: Why is my soil red? or tan or brown or white???

Ever wonder how you can tell if a particular soil will make a good garden?  Soil color can very quickly tell you if you have a good garden soil or not and what you might have to do to it to make it better.  Ever wonder why soils come in a variety of different colors?  Typically it has to do with where the soil came from.  For example, red rocks make red soil.  It also has to do with what is being put into or taken out of the soil by dust or water deposits.  How much water is typically in the soil also influences soil color.  As a naturally curious person looking at your soil in your yard or garden, along the hiking trail, or in a farmers field, soil color can tell you a lot about the land.  And knowing a lot about the land will help you be a better gardener, farmer, or help you explain the local habitat.  The following are the most common soil colors the average person will encounter.  A little understanding of these can greatly aid your gardening skills or your knowledge of
Reddish brown, iron containing, light colored soil
Reddish brown soil: Red soils that have built up an accumulation of iron oxide, which is essentially rust.  The more red the soil the older it is.  In some cases however red soil is derived from red colored rocks such as the red Coconino Sandstone parent material rocks around Sedona, Arizona.  Red soils derived from red rocks also derive their color from iron oxide though.  But how does soil turn red when the parent material rocks are not red?   Interestingly, dust containing iron is deposited on the soil where it oxidizes turning the soil red.  Over time more dust containing iron falls on the soil and the soil becomes increasingly red.  Red color also tells us that the soil is dry for most of the year.

Yellow, iron containing, light colored soil
Yellow soil: Also in indicator of iron in the soil but at much lower levels then red colored soil. 

Dark, humus rich soil
Dark soils:  Typically the darker brown to black the soil the more organic material the soil has in it.  Temperate climates with sufficient rainfall will have darker colored soils due to the build up of humus.  Humus is similar to compost in that it is simply broken down decayed plant materials.  Prairies have the darkest soils due to the huge build up of dead and decaying plant materials.  Dark soils also indicate the richest soils for growing plants and agriculture.  If you are a farmer of gardener you want a dark colored soil being the humus retains water, contains nutrients, and aerates the soil. If a soil is very black, it may indicates either magnesium from the parent material rocks in the soil.  More typically though it indicates the soil is saturated with water so it has very little oxygen in it, turning the soil black.

Light colored soils: Any light colored soil no mater what shade indicates the soil has a low humus content.  These are often rain forest or desert soils.  Rain forests are too hot and wet for humus to accumulate in the soil, it simply breaks down too much.  Deserts are also often too hot for humus to accumulate and don't have much plant material to produce it.  Light color often indicates the soil is leached, or nutrients have been washed out of it.  This all makes light colored soils nutrient poor.  For the gardener with light colored soil you can simply add compost to it, making your soil more productive.  The yellow and reddish brown soil pictures above are examples of light colored, humus poor soil.

Soil with high amounts of calcium carbonate.
Whitish soils:  White soils indicated calcium carbonate or in some cases salt.  This color may also be a result of whitish parent material such as quartzite.  Often in desert soils you will not be able to see white soil being it is buried under other soil colors.  If the surface layers of soil erode off though some of the white soil may be visible.  Calcium carbonate builds up in desert soils due to calcium falling on the soil as dust, rainwater then carries it deeper into the soil where it is retained.  As with iron, the older the soil is, the more dust has fallen on it, and therefore the greater the calcium carbonate content.  This only happens in desert like areas being wet areas wash the calcium out of the soil.  Salt is different in that is is deposited by flowing water on the soil, typically in playas which are seasonal lakes.  Every time water is washed into the lake it carries salt with it, then when the lake drys up the salt is left behind.  For the farmer or gardener these are very bad soils.  They can be remedied to some degree by adding compost though.

Gray colored soil.
Gray soils: Could indicate the soils parent material is gray colored or that the soil is wet most of the year.  In iron rich soils that are saturated with water much of the year, the lack of oxygen turns iron a gray color.

There are a few other soil colors that are a lot less common.  One of the more rarely seen and interesting is purple soil.  Purple soil has a strong sulfur smell and results from sulfur bacteria that grow when a soil is waterlogged for a long period of time.  Which brings up another interesting point, soil smell.  As odd as it might sound a lot of soils have different smells to them.  Anaerobic, soils without oxygen, have a sulfur smell to them.  While aerobic soils, soils with oxygen, have a different smell.  Soils with and without certain nutrients or humus also have different smells.  These smells are a result of different soil microbes like bacteria and fungi, which also contribute to soil color.  I have kind of learned some of these smells with experience and occasionally they can be useful.  Yes, soil covers all the senses; sight, smell, touch, sound in some cases, and some people tell me taste (though I haven't tried it)!

Tuesday, July 12, 2011

Midwestern Eastern Deciduous Forest summer

Late spring (mid-May) in the Eastern Deciduous Forest at Indian Creek Nature Center near Cedar Rapids, Iowa.  Notice how sunny the forest floor is due to the trees not being entirely leafed out.
Summer (late June) in nearly the same location at the Indian Creek Nature Center as the  picture above.  Notice the forest is much darker due to the trees being leafed out.  Not so noticeable in this picture is the thicker summer vegetation.
Summer in the eastern deciduous hardwood forest is quite different from the spring.  Spring can be cool and wet with plenty of sunshine hitting the forest floor (click here for a post on the spring forest).  Come June though, the trees have completely leaved out and the once sunny forest floor can become quite shady, often with only about 5% of sun hits the forest floor.  Spring forest wildflowers disappear and are succeeded by a thicket of more heat and shade tolerant herbaceous plants. While spring forbes can be quite pleasant and easy to hike through, summer forbes are a lot more itchy and on the defense.  Plants like Stinging Nettles and Poison Ivy are extremely abundant and can make a short hike quite painful.  The mosquitoes can also add to this pain and humid warm air (typically in the 80's) can also make this a sweaty experience.  Enough of the negative though!  The forest is quite a refuge from the summer heat and sun.

While the summer forest can be quite itchy,It is quite a refuge from the summer heat and sun.  It is also one of the most wondrous and active habitats around.  If I were to describe the summer forest in one word it would simply be GREEN.  Absolutely everything is beautifully green.  The forest floor is green with mosses and a thick layer of bushes and leafy plants.  Above, smaller understory trees like elms, dogwoods, and ironwoods are green.  Towering higher, canopy trees like oaks, maples, walnuts, ash and hickory's form another thick green layer.  Each of these layers of green is also full of life, which can often be difficult to see due to thick vegetation.  Birds of all types, Cardinals, Indigo Buntings, Cat Birds, Turkeys, Warblers, Gnat Catchers, Ducks among many others fly through out the layers of vegetation and fill the woods with songs all day long.  Whitetail deer, rabbits, and squirrels also abound.

The forest floor as well as the understory are also full of berries this time of year.  Black Raspberries, Dogwood Berries, Mulberries, Chokecherries, and Goose Berries are quite an abundant food supply for forest life or the hiker who can positively identify the plants.  These plants produce their fruit in hopes that some passing animal will eat them and carry the seeds to new locations.

Goose Berries
Black Raspberries
All of this greenness and abundant berry production continues until fall when the weather cools off and drys out.  Once berry production ends, an abundance of nuts that grow on trees throughout summer, including acorns, walnuts, and hickory nuts, ripen and fall off the trees.  But until then, forest life has plenty of time to gather the abundance of the summer forest and relax in the shade until fall and winter when things become harsher.

Sunday, July 10, 2011

Tallgrass Prairie Oak Savannah

Oak Savanna at Rock Island Preserve near Cedar Rapids, Iowa.  This savanna is composed of  Red and Bur Oaks with the prairie grasses Little Bluestem, Big Bluestem and Indian Grass.
Transitioning between the Tallgrass Prairies of the Midwest and the Eastern Deciduous forests is the Oak Savanna.  These are not Simba's "Lion King" African tropical savanna, though they are similar in that they contain grasslands with widely interspersed trees.  And instead of Wildebeests, historically these savannas had large bison herds grazing them. Today the bison are gone except in a few limited protected areas, and due to the relatively rich soil for farming, fire suppression, and abundant grasses for grazing, this ecosystem is one of the most endangered in North America.  Unsurprisingly, Oak Savannas are a mixture of woodland and prairie species.  The fewer trees the more prairie like or the more trees the more woodland like the savanna becomes.  The one most important thing in preventing woodlands from invading the grasslands is fire.  Healthy  savannas require fires about every two years.  Any more than that the trees will be all burned away, any less the woodlands will take over.  Trees such as Bur and Red Oaks are highly adapted to fire with thick fire resistant bark and the ability colonize recently burned areas.  Other tree species are easily killed by fire and therefore woodlands don't invade actively burned grasslands.  When fire is suppressed Hickory, Elm, Basswood, and Maple invade the grassland, converting it into a woodland (At least in Eastern Iowa).

Red and Bur oak savanna at Wickiup Hill Natural Area near Cedar Rapids, Iowa.

Bur and White Oak savanna/woodland where the trees are so dense woodland forbes dominate and prairie species are almost completely absent.  

Thursday, July 7, 2011

Iowa Tallgrass Prairie summer wildflowers

Black Eyed Susan
While Midwestern forests produce an abundance of wildflowers April through May, the Tallgrass Prairies are a lot slower in coming into bloom.  July is the best month to head out for a prairie hike to see an abundance of wildflowers.  Unlike spring forest flowers which are dotted here and their, prairies can produce almost overwhelming numbers of wildflowers at certain times and places.  As for shear numbers and year after year consistency of  flowers I don't know many ecosystems that can match it.  All of the species in this post are perennials and have very deep root systems that can survive fire, grazing, and drought.  In-fact, many if not most Tallgrass Prairie plants thrive with moderate levels of these disturbances.   All of these plants bloom from late June through July.

Prairie Wild Rose, the state flower of Iowa.  Produces a red fruit called a hip that has high vitamin C content.

Common Milkweed found in wetter areas of grasslands.  All portions of the plant are edible when immature and thoroughly boiled.  Mature portions are toxic.

Yarrow, grows in dry areas through out the west.  Has been used for a variety of medicinal purposes including an astringent, healing bruises, aiding healing of colds and flu, as a stimulant, and many many other uses.
Black Eyed Susan, one of the most abundant prairie wildflowers.  State flower of Maryland.  Used as an astringent and treating inflammation.

One of many perennial sunflower species common to the prairie.
Spiderwort, blooms for part on one morning until the petals seem to melt in the afternoon sun.

Thistle, an invasive plant from Eurasia.

Wild Bergamot, has a strong minty fragrance when the leaves are crushed.  It has been used as an antiseptic and tea, among other medicinal uses.  
Hairy Wild Petunia, is in-fact hairy and wild.  Typically found  in very dry locations.
Butterfly Milkweed, found in mesic to dry prairie locations.  The root was used by Native Americans for food.

White Wild Indigo, a very tough poisonous plant.  Can survive grazing and major disturbances such as bull dozing by surviving as a root.  Native Americans used this plant medicinally. 
Pale Purple Cone Flower, an Echinacea sp.  Roots and other portions of plants from the Echinacea sp. are often used to boost immunity.