10. Lone Cypress in Monterey
9. Circus Trees

Basket Tree

The two-legged tree

Ladder tree
8. Giant Sequoias: General Sherman
7. Coast Redwood: Hyperion and Drive-Thru Trees
6. Chapel-Oak of Allouville-Bellefosse
5. Quaking Aspen: Pando (The Trembling Giant)

Aspen grove

Quaking Aspen in winter
4. Montezuma Cypress: The Tule Tree

The Tule Tree Towers over a church next to it.

Full width of the Tule Tree (Image credit: Gengiskanhg, Wikipedia)

Close-up of the tree’s gnarled trunk. Local legends say that you can make out animals like jaguars and elephants in the trunk, giving the tree the nickname of "the Tree of Life"
3. Banyan Tree: Sri Maha Bodhi Tree
2. Bristlecone Pine: Methuselah and Prometheus, the Oldest Trees in the World.

Methuselah Grove (Image Credit: NOVA Online)

Bristlecone pine grove in which Prometheus grew (Image credit: James R. Bouldin, Wikipedia)

Stump of the Prometheus Tree. (Image Credit: James R. Bouldin, Wikipedia)
Today, to protect the trees from the inquisitive traveler, the authorities are keeping their location secret (indeed, there are no photos identifying Methuselah for fear of vandalism).
1. Baobab
can grow up to nearly 100 feet (30 m) tall and 35 feet (11 m) wide. Their defining characteristic: their swollen trunk are actually water storage - the baobab tree can store as much as 31,700
gallon (120,000 l) of water to endure harsh drought conditions.
Baobab trees are native to Madagascar (it’s the country’s national tree!), mainland Africa, and Australia. A cluster of "the grandest of all" baobab trees (Adansonia grandidieri) can be found in
the Baobab Avenue, near Morondava, in Madagascar:

(Image credit: Fox-Talbot, Wikipedia)

Teapot baobab (Image credit: Gilles Croissant)
The baobab trees in Africa are amazing as well:

Baobab near Bulawayo, Zimbabwe (Image credit: ironmanix [flickr])
There are many practical uses of baobab trees, like for a toilet:

A toilet built inside a baobab tree in the Kayila Lodge, Zambia
(Image credit: Steve Makin [flickr])
… and even for a prison:

A "Prison Baob" tree in Western Australia (Image credit: yewenyi [flickr])