The towering titans: forget the traditional definition of a tree. There are a few species-11 to be exact-that defy such a mundane description.

Any toddler knows what a tree is, but not all adults, including foresters, agree on how to define them. Most definitions emphasize their woody and perennial nature and a single stem near the ground. Arborists, foresters, dendrologists, and big tree hunters also require such plants to achieve a certain size or else be relegated to the ignominy of a shrub.

There are different standards for separating trees from shrubs, but everyone allows Mother Nature to decide how big a tree can grow. Presumably, a woody, single-stemmed, perennial plant with a crown in the stratosphere would still be just a tree.

Imagine if you lined up all the kinds of North American trees by maximum size. When you stepped back to look, here's what you'd see: a row of trees, hundreds of species long, with sizes ranging from 25 points to 1,321 points.

A full third would offer champs that tip the scales at less than 100 points. Within each 100-point range thereafter, the number of champions gradually declines. There are 177 in the 100s, 124 in the 200s, 95 in the 300s, 56 in the 400s, and 23 in the 500s.

We've now covered more than 98 percent of all North American trees but we're not yet halfway through the range of possible sizes. On our imaginary line of trees, from the 25-point northern bayberry to the 597-point noble fir, an imaginary squirrel could easily hop from one tree to the next, with never more than a 15-point gap to cross. Our line gets a little thin in the 600s with only six trees, but they are still fairly evenly spaced, with the largest gap only 26 points wide. But now we are left with only seven trees to cover a span of 622 points!

Perhaps foresters someday will come up with a definition of megatree based on volume, the ultimate but often elusive measure of size. Or maybe there will be separate megatree criteria for height, circumference, and crown spread. For now, we'll use the arbitrary limit of 650 points, which separates the 11 biggest champion trees in America. Here they are, in order of increasing astonishment.

#11 SUGAR PINE 

This is the largest pine in the world and, fittingly, it has the largest pine cones. Even if they miss your head, a 2-foot pine cone dropping nearby can give you a Chicken Little moment. The champion sugar pine just reaches megatree size with 659 points. Although much of the surrounding area has been logged, the biggest sugar pine is currently protected in a 10-acre grove of old-growth high above the North Fork of the Stanislaus River in the Sierras of California. You can see and even walk from one side to the other through an old fire scar at the base. It's sobering to pause inside and suddenly realize that the equivalent weight of 50 full-size pickups is balanced directly above your head, with much of its original support missing.

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#10 MONTEREY CYPRESS 

In the natural world, this species is restricted to the coast of Monterey Bay where it is often tortured, twisted, and flattened by salt-laden onshore winds. Only where it has been planted and protected farther inland has its megatree potential been realized. The 668-point champion grows beside a country road near Pescadero, California, about 5 miles from the dwarfing coastal winds but still within the protective fog belt, which promotes rapid growth by reducing water loss. The cypress' short, massive trunk stands more than 14 feet thick before branching off in 20 different directions. The biggest Monterey cypress is also notable for having a 116-foot crown spread, second among conifers after the 130-foot crown of the Torrey pine.

#9 CALIFORNIA-LAUREL

It is almost a prerequisite that to reach megatree size a tree must be a conifer. The 674-point champion California-laurel is the only angiosperm to break this rule, although its complex architecture hints that it may have broken the multi-stem rule long ago. But its history of growth is now buried within a trunk 14 feet thick, which with a 119-foot spread and tree-sized mossy limbs, makes for one jaw-dropping megatree.

#8 PORT-ORFORD-CEDAR

A small species range centered in the Siskiyou Mountains of Oregon and California, a quality of wood once deemed incomparable, and an introduced root fungus have conspired to nearly eliminate the Port-Orford-cedar from the megatree category. This species often tops out above 200 feet and stumps have been found measuring 17 feet across, making its true potential well over 800 points! The current champion, in Oregon's Coquille River Valley, is a "mere" 691 points, with a 12-foot thick trunk and a 229-foot height. Since its closest challenger scores only 564 points, the champion Port-Orford-cedar may be the species' last living megatree, itself a shadow of their former greatness.

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#7 COMMON BALDCYPRESS

The common baldcypress is the only megatree east of the Cascades and Sierras, and one of only two that score in the 700s. Some might argue that the champ, which grows in a southern Louisiana swamp, is more monster than megatree because of its double trunk and extreme flare. Only 83 feet tall, the Cat Island baldcypress has a nearly 54-foot circumference that inflates its score to a whopping 748 points. The next largest baldcypress, the old-growth Senator of Longwood, Florida, has 557 points and probably the greatest volume (4217 cubic feet) of any tree in the East. The Senator has little basal flare, so it seems likely that there were baldcypress megatrees before logging. Old-growth baldcypresses have been accurately aged to at least 1,600 years but unless restraint and foresight survive the comings and goings of empires, we may never know their true megatree potential.

#6 BLUEGUM EUCALYPTUS

In Australia, bluegum eucalyptus is known to grow more than 300 feet tall. America's national champ, near Petrolia, California, is less than half that height because it grows in a fencerow instead of a forest. But its 48-foot girth helps give it an impressive 759 points. Bluegum eucalyptus was introduced into California in 1856. Today, although it's valued as a windbreak and ornamental tree, bluegum is considered a major invasive exotic by the California Invasive Plant Council, and state and national parks seek to remove it from natural areas. The champion bluegum may be the biggest naturalized tree and the biggest hardwood in America, but for many, it's also the biggest weed.

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We now enter the realm of the undisputed megatrees. The following five species not only routinely surpass 650 points, they are the only species represented by champions boasting more than 800 points.

#5 COAST DOUGLAS-FIR

Unfortunately for megatree lovers, old-growth Douglas-fir forests were loved as much for their board-feet as their skyward view, meaning only a tiny fraction of these living treasures remain and the greatest specimens are gone. Had it been otherwise, the "world's tallest trees" title would be held jointly by the coast Doug-fir and the also cutover Australian mountain ash (Eucalyptus regnans), both of which were known to exceed 400 feet. The biggest coast Douglas-fir ever measured in all dimensions was the Mineral Tree, which grew southwest of Mount Rainier and fell in 1930 when it was 1,020 years old. At one time it was 393 feet tall, more than 15 feet in diameter, and would have scored about 991 points!

The current co-champions, topping out at a little over 800 points each, have a bit of catching up to do, but they are still quite impressive. The Queets Fir (809 points) in the Olympic rainforest of Washington has a broken top, giving it a height of only 200 feet, but it is six inches thicker than the Mineral Tree. The 829-point Ol' Jed Douglas-fir in Jedediah Smith Redwoods State Park, California, is 2 feet slimmer but tops out at a lofty 301 feet

#4 SITKA SPRUCE

Favored for airplane construction because of their incomparable strength-to-weight ratio, the accessible Sitka spruce of the Pacific Northwest were heavily logged to support both world war efforts, costing the tree a chance to survive as old-growth across most of its range. A far more friendly battle took place in the 1980s between Oregon and Washington over who had the bigger specimen. In the end the two states declared a peaceful draw, and both trees remain on the Register today. Washington's cochamp, near Quinault Lake in the Olympic rainforest, has a diameter of nearly 18 feet, boosting its point total to 883. The Oregon tree, near Seaside, is about a foot slimmer but, at a height of 204 feet, is 13 feet taller with 856 points. Together, these and other remaining megatree spruces leave no doubt that the Sitka reigns as the world's biggest spruce and the second biggest member of the pine family after the historically bigger coast Douglas-fir.

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#3 WESTERN REDCEDAR

Now we enter the 900-point range, a category occupied solely by another denizen of the Pacific Northwest, the western redcedar. Western redcedars' resistence to rot--which made the trees ideal for canoes, totem poles, and roofing--gives them long lives and the chance to reach goliath proportions. This durability in contact with the ground is offset by the crown's vulnerability to dieback from drought. Old trees have endured many dry years, each evidenced by a separate, usually dead, top. But, while living, the crowns all fed the continuously growing main stem to create the megatrees of today. If not for a grossly underestimated height, the biggest western redcedar would have reigned continuously since it was crowned in 1941. The 920-point champion grows in Washington on the other side of Quinault Lake from the co-champ Sitka spruce. Now considered 174 feet tall (instead of 1941's guess of 100 feet), it has a tape-stretching 61-foot girth and is, by volume, possibly the world's biggest tree outside of California. Only time will tell whether its surviving strip of cambium, just 2 feet wide, will live long enough to add significantly to its already great stature.

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#2 COAST REDWOOD

Coast redwoods, and the giant sequoias that follow, are big--I mean really big--even compared to other megatrees. A huge gap of 359 points separates the biggest western redcedar from the biggest coast redwood. Perhaps they deserve to be called gigatrees. Redwood forests have so much biomass you almost feel lighter as you walk, antlike, below their gravitational pull.

There are three co-champion coast redwoods, all discovered by members of the megatree team of Ron Hildebrant. Michael Taylor, and Steve Sillett. The 1,223-point Del Norte Titan, 307 feet tall with a diameter of nearly 24 feet, grows along Mill Creek in Jedediah Smith Redwoods State Park in California. It's the biggest coast redwood by volume, at 36,890 cubic feet. Only 14 trees in the world, all giant sequoias, have greater volumes, although, according to megatree scientist, artist, and measurer extraordinare Robert Van Pelt, at least two logged coast redwoods had volumes that actually beat the General Sherman giant sequoia. Just across the creek from the Del Norte Titan grows the co-champion Lost Monarch, which has a sequoia-sized diameter of 25 feet and is the tallest champion in the country, soaring to 321 feet--15 feet higher than the Statue of Liberty. These impressive dimensions give the Lost Monarch the largest point total--1,290--of the three co-champions and place it just 31 points shy of the General Sherman giant sequoia. The third co-champ is the Sir Issac Newton tree, a soaring 311 feet tall, with a diameter of 23 feet, and a megatree total of 1,203 points.

#1 GIANT SEQUOIA

All rise. Here is the champion of champions, the king of kings: 1,312 points, 261 feet tall, with a trunk more than 85 feet around. Although a coast redwood might someday rack up more points, the General Sherman giant sequoia is 50 percent bigger by volume than any redwood alive today. And, if that's not impressive enough, nearly 12 percent bigger than the next biggest giant sequoia. From our normal eye-level perspective up close to the base, we are most impressed by a big tree's huge lower trunk and, enhanced by perspective, the near-vanishing point of its uppermost twig. But the most amazing fact of General Sherman's size is how much of it is up where the birds fly. Even if you discount everything below the 150-foot level, where the trunk is still 16 feet in diameter, General Sherman scores 754 points and still easily qualifies as a megatree! This most mega of megatrees has dropped 400-point branches that were more than 6 feet in diameter and 140 feet long. If you could place the General Sherman on one side of a seesaw, it would take a town of more than 60,000 people on the other side to raise it.

Given that, we now know how Mother Nature currently defines the upper size limit for a megatree. Any single-stemmed tree that is bigger than General Sherman must be either a fossil, a memory, or on a smaller planet.

STORY AND PHOTOS BY WHIT BRONAUGH

Whit Bronaugh writes about and admires megatrees from his home in Eugene, Oregon.