Monday, February 27, 2012

Incredible Seeds

Plant grown from 32,000 year old seed.
Recently, Russian scientists unearthed 32,000 year old seeds from Siberian permafrost.  These seeds had remained frozen underground at an average temperature of 19 degrees Fahrenheit over these millenniums.  They were hidden by a squirrel in its burrow but were subsequently buried under 38 meters of sediments and permafrost.  While finding ancient seeds buried deep in permafrost in itself is quite impressive, even more impressive is the fact that these scientists were actually able to germinate and grow some of these seeds!  Previously, the unofficially oldest seed ever germinated and grown was a 10,000 year old lupine seed found by a gold miner in the Canadian Yukon.   Officially though, the oldest seed ever germinated was a 2,000 year old Methuselah tree seed (ancestor of the modern date palm) found in ancient Jewish ruins located in modern day Israel (Click here for story).  So this new official record of 32,000 years blows away any of the previous records.  It also attests to the seeds amazing ability to survive adverse conditions for extremely long periods of time, simply waiting for the right conditions to germinate and grow again.  Extended dormancy of seeds is quite common in desert plants where seeds commonly lay dormant in dry desert soils for decades, waiting for just the right temperature and moisture conditions.  Marshes and permafrost areas also store seeds for long periods of time in their water saturated and or frozen soil conditions. 

Here's the story from National Geographic: 32,000-Year-Old Plant Brought Back to Life—Oldest Yet

 Supposedly, the ancient plant looks slightly different from modern day plants.  I couldn't find any images to verify this but it will be interesting to compare the genetics of the ancient to modern day plants.  I am sure a lot more research will go into the genetics of this ancient plant, comparing it to its modern ancestors.  I am guessing someone will do a little more digging in the area in order to unearth more frozen seeds to see what can be found. 

Friday, February 24, 2012

February in the Sonoran Desert

Fiddleneck and Mexican Poppy.
Well it has been a very dry past few months here in the Sonoran Desert.  There has been no significant rainfall in the Phoenix area since mid December when we received about one inch of rainfall.  It also has been slightly warmer than usual which has forced many of the wildflowers that germinated in December into bloom early.  Even so, the weather has been absolutely beautiful for months straight.  Every day is just another day in paradise… I just wish it would rain! 

Normally, there is not a lot blooming in the desert right now.  Good rainfall in December followed by months with no significant rainfall though has resulted in a few small wildflowers blooming here and there though.  Desert wildflowers are highly adapted to this type of rainfall pattern.  Of course they grow best with more rain but still have the ability to produce after only one good rainfall.  Most Sonoran Desert wildflowers will lay dormant as seeds in the soil for years.  Only when temperatures are just right and there is sufficient rainfall will these seeds germinate.  Seeds can patiently wait decades for just the right germination conditions.  If after germination no rainfall is received the flower can quickly produce a few tiny flowers and seed before dying in the desert drought.  If more rainfall is received the plant can grow much larger, produce more flowers and more seeds.  This year with our lack of rain there are quite a few tiny wildflowers beginning to show themselves.  I have found Mexican Poppy, Lupine, Scorpionweed, Fiddleneck, and Small-Flowered Eurcrypta.  Many only a few inches tall.  In better rainfall years these flowers can often reach a foot or more.  Of the more woody plants Wolfberry is the only one in I noticed blooming in abundance, and the bees sure seem to like it.

Desert Mistletoe berries also are ripe across the desert right now.  Many Mesquites, Ironwoods, and Palo Verde trees are infected with this parasite.  Right now Phainopeplas can be found perching atop many of these infected trees and eating the abundance of reddish berries.  Of all the desert birds, the Phainopepla is the fondest and has the most intimate relationship with mistletoe.  Of course the berries feed the bird, but mistletoe also depends on the bird to distribute the seeds once they pass through the digestive tract.  There are many other birds in the desert being the northward migration is beginning.  In-fact, the other day I saw an American Robin.  If you are lucky enough to be near some water there are an abundance of waterfowl migrating though.  Canadian Geese, American Coot, Mallards, Ring-Necked, and Redheads are all relatively common right now. 
Scorpion flower
As we move into March it looks like it will continue to be dry.  Without rain, wildflower blooms should peak within the next three weeks or so.  Typically we have a decent rain mid-March that will extend the wildflower season a little longer though.  But come late March and April our days of beautiful weather are numbered as the heat begins creeping up on us.  

Monday, February 20, 2012

Life of a Hickory Tree Part 3

This is part three and the last post of the Life of a Hickory Tree.

As the hickory slowly grows it develops a hard strong wood.  While this wood structure helps the tree survive drought and windy conditions, it also makes it highly useful to humans.  Hickory is well known for making strong tool handles.  Native Americans frequently made bows and arrows from the wood.  Settlers also used it to make wagon wheels, skis, and old fashion golf clubs.  It is also great fire wood being its dense wood burns long and hot making great charcoal.  This extremely useful wood made the hickories some of the first to be cut down by early settlers.  Even today hickory is used in making tools, all kinds of wood craft, and for smoke curing meats.  In my opinion, hickory smoked meats really are some of the best tasting!

As the shagbark hickory grows it develops a tall straight trunk and often columnar shaped tree.  Oak trees are often spreading, making them especially adapted to growing in grasslands where they can spread their branches horizontally to gather light and there is little competition with nearby trees shading them.  Hickories with their narrower more columnar shape are more of a woodland species grow up towards sunlight as they compete with nearby trees.  As the hickory slowly grows it loses its ability to re-sprout if damaged by fire.  Larger trees however are increasingly resistant to fire as they grow.  This fire resistance though is nothing compared to oaks thick insulating bark and large hickories still can only tolerate very low intensity ground fires.  If larger trees are exposed to higher intensity fires, even if the flames do not initially kill the tree, damaged cambium becomes highly prone to rot which can subsequently kill the tree. 
For the first 20 to 30 years of life, the shagbark produces a beautifully smooth, gray bark.  This bark is very thin and even a very shallow cut into it will produce the green cambium.  As the tree ages though the bark becomes increasingly scaly, rough, and a gray-black color.  A much harder and slightly thicker layer of bark covers the trunk.  By the time the tree reaches 30 years of age the bark begins to fissure and flake outwards, producing the classic shaggy bark these trees are known for.  I have never heard anything about the fire resistance of this shaggy character of bark but I suspect it catches fire relatively well and it part of the reason these trees are not very fire resistant.  The shaggy bark is so easily recognizable and memorable that once told, even a child can easily identify the tree.  The flaky bark also is quite useful as a hiding place for insects and a roosting location for bats.  The fact that many bugs hide among the shaggy bark benefits many species of insect loving birds that search out the flakes and crevices for dinner.  Shagbark hickory is such an important bat roosting location that when mature shagbarks are logged a bat population can nearly disappear.  Some birds, such as the brown creeper, also nest under bark flakes.  Humans also prior to 1900 or so utilized the inner bark to produce a yellow dye.  Today, a few people in the east boil the bark with sugar in a secret process to produce shagbark hickory syrup which some claim puts maple syrup to shame. 
The shaggy bark of this hickory provides homes for many insects as well as some birds and bats.  
Around 40 years of age the shagbark begins to produce larger mast crops.  Large mast production occurs every one to five years depending on spring weather conditions.  Animal populations typically fluctuate along with large oak and hickory mast years.  In years with large mast production there is a large amount of food to go around for deer, bear, turkey, woodpeckers, ducks, and jays.  As a result these animals will often produce many young and the population will grow.  Years with low mast crops will result in little food allowing fewer wildlife offspring to survive therefore causing populations to shrink.  Though inconsistent in production and causing the rise, fall and rise again, in many animal populations, the overall benefit of these mast producing trees is huge.  Other trees, such as maples, produce huge numbers of seeds every year but benefit wildlife populations little in comparison of the oaks and hickories. 
The hickory can continue to grow and produce mast until about 200 years of age, after that most trees begin to decline.  Maximum lifespan is likely between 200 and 300 years.  At these old ages the hickory has become a tall straight tree of 70 to 80 feet tall.  Canopy width is typically about half or less of their height.  At this stage in life the shagbark has become a stately tree.  The long flakes of shaggy bark make these trees presence in the woodland clear.  Dark colored and straight trunks with their beautiful dark green foliage make these trees stately columns.  In spring these leaves burst forth from large scarlet colored leaf buds.  In fall the bright yellow leaves are a strong contrast against the more drab yellow and reds of neighboring oaks.  Though smaller, shorter lived, and less common than the oak, the hickory is a cornerstone tree to Midwestern and Eastern woodlands.  It is unfortunate it often takes a backseat to oaks being it is such a magnificent tree in itself.  

Friday, February 17, 2012

Life of a Hickory Tree Part 2

A yellow Hickory leaf.
Not only are hickory nuts sought out by wildlife, humans also have partook in the gathering of these nuts.  Though hickories were less common than oaks in Midwestern and Eastern wooded areas they still were an important food source for Native Americans.  Being oaks and hickories often grow right alongside each other I am sure hickory nuts were often gathered with acorns in the fall.  Both fall from trees at approximately the same time.  Even today hickory nuts are one of the most popular types of tree nuts eaten.  The pecan comes from a hickory tree closely related to the shagbark.  While many people claim that shagbarks produce a nut that tastes superior to the pecan, the shagbark unfortunately is an inconsistent producer.  Pecans are produced consistently year after year while shagbark nuts are produced in an abundance only every few years or so.  Being farmers don’t like to wait a few years to obtain a harvest, the pecan quickly dominated agriculturally.  So the next time you eat pecan pie or pralines remember the hickory they grew on.  Other hickory trees also produce nuts however, none of them taste anywhere near as good as the pecan or shagbark.  The pignut and bitternut hickories produce nuts that taste about as good as their names sound.  I have tasted some before and couldn’t tolerate the taste for more than a few seconds. 
Hickory nuts.
Ideally, the lost hickory nut will find itself in a disturbed location such as along a forest edge, a recently burned area or in a forest clearing where larger canopy trees have recently fallen or been logged.  While hickories do tolerate some shade, they prefer lots of sun, so recently disturbed areas are preferred.  Typically, oaks will invade an area before hickories do but, if an area has a lower level of disturbance, frequently hickories will closely follow the oaks in becoming established.  The Shagbark Hickory is the most common type of hickory of the oak-hickory forest.  While this hickory is tolerant of most soil types it does not do well in wet soils and prefers the drier soils.  So ideally the nut will be cached in mesic to dry soil.  Once here, the seed must be exposed to cold winter temperatures before it will germinate.  After exposure to winter cold however, soil moistened by melting snow and warmer temperatures cause the seed to rapidly germinate.  Immediately at germination, the seed puts all of its energy into developing a thick strong taproot.  This taproot can be several inches long before any green shoots sprout above ground.  But once green sprouts do appear, light harvested through photosynthesis is rapidly converted into energy to grow this taproot.  Over the lifespan of this tree, this taproot will be the primary root from which smaller roots venturing outward.  As a result, hickories are considered one of the sturdiest trees of the forest.  The hickories, life philosophy, at least for the first several years, is root before shoot; this is similar to the oak.  This results in an extremely slow growing tree and often other trees out-compete hickories by shading them out.  Amazingly, even slow growing oak trees outpace the hickory.  But slow growth emphasizing a strong taproot builds a well established, durable tree with high quality wood.  Within the prairie to forest transition, wind and drought are common problems that must be overcome for survival.  The great strength hickories gain from deep root to high limbs allows them to survive strong winds with firm anchoring, strong stature, and deep probing in search of hidden soil moisture.
Even though hickories are not well adapted to brush or grass fires like this one, young hickories still can sprout back after the fire.
Establishing a strong taproot not only overcomes drought and wind, it overcomes another factor common to the prairie to forest transition: fire.  Fires are most common in fall and spring.  In the fall, low intensity ground fires can disturb an area, clearing competing vegetation, and making it an ideal location for a hickory seedling to establish itself.  In spring, fire can be much more dangerous to hickory sprouts by killing them.  Hickory seedlings are also targets for grazing animals such as the white tail deer.  However, if a hickory sprout or seedling is killed by fire or eaten, the well established root can rapidly resprout.  Once resprouted after fire, competing vegetation has been burned away, and the young hickory can rapidly grow without competition.  This ability to resprout maintains itself until the tree is 20 or so years old.  At this point, fire will more likely kill the tree and the root will not be able to resprout.  Hickories do not have the thick fire-resistant bark upland oaks do.  Their bark is rather thin and is easily damaged by fire, so hickories can only establish themselves in woodland areas that are burned less frequently.  While oaks can survive ground fires about every two to ten years, hickory forests can only survive low intensity fires every twenty or more years.  For this reason, hickories are commonly found in slightly moister areas that have lower fire frequencies. 

Tuesday, February 14, 2012

Life of a Hickory Tree Part 1

Oak-Hickory Forest found in Eastern Iowa.  The red trees are oaks and the yellow trees Shagbark Hickory.
This is the first of a four part series on the Shagbark Hickory tree of the Oak-Hickory Forest found in the Midwestern and Eastern United States.  It is sort of a continuation of the Life of an Oak blogs posts from last fall.  

In upland Oak-Hickory forests oaks draw all the attention and excitement.  Typically, oaks are larger and more abundant, but it takes hickory trees to make an Oak-Hickory forest of course.  Hickories have very similar life histories when compared to oaks of the Eastern and Midwestern United States, and this is exactly why oaks and hickories are closely associated.  The hickory however, is more of a forest species and indicates another step in transition from prairies more common to the west, to forests more common to the east.  In the Midwest, where this prairie to forest transition takes place, the Shagbark is the most common hickory of this forest type.  When first settled in the mid-1800's the Shagbark was an extremely minor tree in oak savannas but more common in oak woodlands, especially in slightly moister areas where fires burned less frequently.  Settlers made quick use of the hickory trees, chopping them down and using them to build strong tools and for burning.  Savanna and woodland oaks however, were often too large to cut down with ordinary 1800's era tools but the smaller hickories were much easier to cut and process.  For this reason, and because they were less common in the first place, hickories vanished far before oaks did.  As a result, hickories may be in lower proportions even today in oak forests.  Today however, I have seen an abundance of young hickories in oak forests, making me think their populations are growing in some areas.  Fire suppression in the modern era may be contributing to this increase of hickories as well as a normal repopulation of areas where hickories historically were completely eliminated by logging. 

Life as a nut

For hickories, life begins with what most of us would consider a nut.  Scientists however tell us that hickory nuts are not in-fact nuts, rather they are fruit.  Let me explain.  First of all, a fruit is any plant structure that contains seed.  Nuts on the other hand are simply a large dry seed enclosed in a dry shell.  While the hickory does have a large dry seed enclosed in a dry shell, early in its life this nut is enclosed in fleshy, or should I say fruity, plant material.  As the seed matures this fleshy container hardens into a dense woody shell that even the most pesky of squirrels can't penetrate.  Traditional ideas of succulent sweet fruit does not fit the hickory nut fruit.  This dense husk like flesh protects the hickory seed extremely well as it grows on the tree through summer.  However, as if to say, "you can eat me when I'm ready," the thick husk begins to split into four sections once maturity is reached in early fall.  Breaking of the husk happens as the fruit dries out, just before or just after it falls from the tree.  Once the husk splits, the hickory seed, or nut, is no longer safe.  For our purposes here, we will refer to the hickory fruit as a nut.  Which despite what scientists say, still seems to make the most sense.
Some Hickory fruits, or nuts.
In a similar way to the upland oak, the upland hickory begins its life as a nut.  Mother hickories send their progeny off with a simple quick drop from canopy to forest floor.  Once on the ground with the husk split open, hickory nuts don't move much except for maybe a short roll downhill.  Here, the nuts become a coveted food source.  In most years, these predators will quickly find and consume nearly every nut produced by the mother hickory.  However, every few years or so, such an abundance of nuts are produced that there are many left over.  In these years of abundant mast (nut) production predators are overwhelmed but still typically locate nearly all the seeds that fall from the tree.  However, instead of consuming the nuts immediately, certain forest creatures cache the abundance throughout the forest.  Deer, turkey, and bears all immediately eat hickory nuts in hopes of fattening up for winter.  Other predators such as squirrels, chipmunks, Bluejays, and woodpeckers will gather seeds, hiding them in caches throughout the forest and new locations outside of the forest.  These caches of nuts are then to be consumed later in winter when other food sources are scarce.  Woodpeckers will most often cache large amounts of seeds in tree cavities where they will easily be relocated.  Squirrels, jays, and chipmunks will hide seeds by burying them in many caches just below the soil surface, then attempt to relocate them later in the winter.  Amazingly, most of these hidden caches will be relocated and eaten.  A very tiny percentage of nuts actually survive the initial scavenging of forest creatures.  In good mast production years many however, will be lost and never be recovered.  Then, once lost, nuts find themselves in an ideal location, hidden away from predators, protected from the elements, planted and ready for germination.
Blue Jays commonly cache large seeds including the hickory nut.

Friday, February 10, 2012

The Best Dietary Guidelines: Healthy Eating Plate and Pyramid

The latest and healthiest dietary guideline, Harvard's Healthy Eating Plate.

There is a decent amount of criticism of the old USDA food pyramids and the latest Choose My Plate dietary guidelines.  Though I still think the latest Choose My Plate is pretty good there is clearly some influence by lobbyists and the industry evident in it.  The most obvious would be the presence of the dairy food group.  The latest research shows dairy is not necessary for obtaining calcium, being the calcium present in dairy is not easily absorbed and calcium in vegetable products is very easy to absorb.  As sort of a response to the USDA’s food pyramids and plates, Harvard has produced the Healthy Eating Pyramid and Plate.  One of the advantages of Harvard’s pyramid and plate it what the old food pyramids did, they show you what and how much to eat in a single picture.  When it comes to diet, a picture really is worth a thousand words.  Unfortunately, the new USDA Choose My Plate moves away from this user friendly picture.  Fortunately, the Healthy Eating Food Pyramid and Plate are extremely user friendly.

Harvard’s Healthy Eating Food Pyramid and Plate: 

The best food pyramid out there.  Sorry the image quality doesn't copy so nice from the Harvard School of Health website.
A part from dairy, the Harvard food pyramid also differs in the amount of fruits and veggies it suggests.  When I examined the USDA plate I found out it had limits on fruit and veggie intake.  Harvard’s food pyramid however suggests more is better, which is strongly scientifically based.  Harvard’s also reduces the amount of carbohydrates and increases the amount of unsaturated fats, or oils.  This is a huge improvement being over consumption of carbohydrates and under consumption of unsaturated fats (oils) is the major cause of high cholesterol and heart disease.  Last major difference I noticed was that protein intake is higher in Harvard’s pyramid.  Protein is suggested to be from white meats, veggies, and to avoid red and processed meats. 

USDA's latest dietary guide line, Choose My Plate.  Harder to use than pyramids being you can't actually tell how much of what you are supposed to eat just by looking at it.  This plate is also unfortunately influenced by industrial rather than health interests.

The old USDA food pyramid that now has been replaced by Choose My Plate.  Pretty good but not as good as the Healthy Eating Pyramid.
The website for the Healthy Eating Food Pyramid and Plate isn’t quite as nice as the USDA’s.  However, the information on the Healthy Eating Pyramid and Plate website is far superior, with lots of clear scientifically based information to back it up.  From my perspective the Healthy Eating Pyramid and Plate is far superior to anything that has proceeded it, is easy to understand, and easy to follow.  I love the fact that it uses great scientific information to backup and explain it. 


Monday, February 6, 2012

Teddy Bear Cholla Cactus: White Tank Mountains Ironwood Trail

Three species of cactus along the Ironwood Trail.  Hedgehog cactus lower left, barrel cactus lower right, and teddy bear cholla middle.

The Ironwood Trail is only a 0.9 mile easy hike across a flat bajada, but as for viewing cacti it is pretty good.  When I say viewing cacti, I specifically have in mind Teddy Bear Cholla, and the size of these cacti along this trail, along with the size of this population is rather remarkable.  Typically I would say Teddy Bear Chollas reach about three to four feet in height.  Here however, the stand appears significantly older and there is a sizable population over five feet.  As anyone who has been around Teddy Bear Chollas for more than five minutes knows, these cacti are nice to look at but only at a distance.  And their nasty nature is one of the major reasons why these cacti are so abundant along this trail.

When looking at a Teddy Bear Cholla at a distance it defiantly gives the appearance of a nice fuzzy teddy bear.  The huge density of large spines creates this deceptive appearance and often give the cactus a nice golden orah in the sun.  If you examine one of the joints of this cholla up-close you will notice the spines are so dense it is impossible to touch any green portions.  Using a microscope you would also notice that the spines have many fishhook like barbs on them.  These spines and barbs are what give this cactus its nasty reputation.  The density of spines makes them impossible to avoid and the barbs make the spines difficult to remove, and why you will want to stay far away.  I have had two occasions where I accidently had joints of this cactus firmly lodged in my leg as a result of hiking too close.  The difficulty and pain of removing them I will not soon forget.  A day of two after this, a huge bruise developed where they were lodged.  I have also seen a few dogs get joints lodged in their feet, the resulting yelping and whining was unbelievable.  So stay far away!
Teddy bear cholla cacti.  
This nasty nature of this cactus is the exact reason why it is so abundant on this trail.  You would expect all plants to reproduce through seed, but not the Teddy Bear Cholla.  This cholla does produce seeds but typically none are viable.  Quite a weird problem for any plant to have.  There isn’t even much emphasis by this plant to produce viable seeds.  The cactus doesn’t produce many flowers at all.  Flowers that are produced are green and do not attract much attention.  This problem is easily overcome by the cactus hitching a ride on some unfortunate animal passing by.

As you may know, cacti have the ability to root into soil from nearly any green fleshy portion of their stems, pads , or joints.  Teddy Bear Chollas are especially good at this.  First of all, their joints are loosely attached to the plant.  I frequently see joints simply falling off even with the slightest disturbance or breeze.  Once on the ground these joints can root into the soil and develop into another plant.  Secondly, the spines are extremely sharp easily sticking into the flesh of any animal that passes by and the barbed spines hold the joint in the flesh making it difficult to remove.  When the joint sticks into an animal, the animal then transports it, albeit unwillingly, to another location.  The joint will eventually fall off and once on the ground can root itself and grow into a new plant.  This cholla seems to prefer  soils with caliche but overall they are not really picky and can grow in some of the worst soils were no other plants will grow.

This easily detachable, easily carried, easily rooted ability of the cholla makes it extremely widespread and why it is so abundant on the White Tank Mountains Ironwood Trail.  Prior to the 1980’s the White Tanks were grazed and I would guess the flat area around Ironwood Trail had an especially high concentration of grazing.  As a result cattle frequently bumped into and carried around cholla joints to be deposited elsewhere.  This caused a huge increase in the Teddy Bear Cholla population in this area and the population remains to this day.  Even today, humans, deer, packrats, and other animals continue to transport cholla joints around.  I am sure this is at a much slower rate than the cows used to do though. 

Oh-ya, there are also quite a few Ironwood trees on the Ironwood Trail, as the name implies.  Their presence though is dwarfed by all the Teddy Bear Chollas.  As for my 2012 New Years resolution of hiking 150 miles and blogging nature tours I am currently at 22 miles.  At this rate I will be done before June!

Friday, February 3, 2012

How to Grow an Avocado: Grocery Store Produce Section Plants

If you were to go out and buy fruit trees it could cost you quite a bit of money, that is, if you could find them.  Fruit trees can be quite difficult to come by and if you do, they are expensive.  But, if you are a little adventurous you can purchase fruits from the grocery store produce section, plant the seeds and find out what happens.  Of course, this will take a little patience and an experimental mind-frame but a little work and a little money can produce a lot of interesting plants.  Not only that, plants grown from grocery store produce can teach you a lot about cultivating plants.  If you want to change your brown thumb into a green thumb, try your hand at growing seeds you find in grocery store produce.  There are probably a couple dozen different plants you can grow from the grocery store but today we will be talking about the avocado.

Avocados are relatively new to the supermarket, especially in the north.  They have been around a long time though in Florida, Texas, and California.  They aren't as ubiquitous as the banana but with a little searching most grocery store produce sections will turn up a small display.  Sometimes grocery store avocados can be a little pricey, say a dollar or more per fruit, but that is nothing compared to the price of purchasing a tree or the great experience you will get trying to grow it yourself.  Once you buy the avocado the first thing you have to do is eat it.  Typically this isn’t very hard being most people love avocados.  And these fruits are extremely healthy for you with healthy unsaturated fats, fiber, and lots of vitamins.  Studies have shown that avocados decrease cholesterol levels and possibly have anti-cancer effects.  If you don’t want to eat your avocado you can simply cut it open and take the seed out.  Once you have the seed, clean it off well and let it dry for a day or so. 
An avocado seedling.  Note the seed planted partially under the surface.
After drying, bury about three-quarters of the seed in some sort of soil.  The rounded side of the seed should be buried and the more pointed one-quarter end of the seed above the soil.  Keep the seed in a relatively warm location and make sure the soil stays moist.  Then wait, it may take up to two months for the seed to germinate.  I have achieved about a 50% germination rate this way.  There are many other ways to germinate avocado seeds which include wrapping the seed in wet paper towels or letting the round end soak in water.  These other methods have been far less successful for me. 

Once you do germinate a seed you will have to be patient again.  If you want fruit you will likely have to wait five or more years.  Avocados also do not tolerate temperatures much below freezing so if you live where it freezes you will have to grow it inside.  Avocados make nice house plants but if you want it to bear fruit it will need lots of light.