The Integral Trees is a 1984 science fiction

Science fiction

Science fiction is a genre of fiction dealing with imaginary but more or less plausible content such as future settings, futuristic science and technology, space travel, aliens, and paranormal abilities...

 novel by Larry Niven

Larry Niven

Laurence van Cott Niven / ˈlæri ˈnɪvən/ is an American science fiction author. His best-known work is Ringworld , which received Hugo, Locus, Ditmar, and Nebula awards. His work is primarily hard science fiction, using big science concepts and theoretical physics...

 (first published as a serial in Analog in 1983). Like much of Niven's work, the story is heavily influenced by the setting: a gas torus

Gas torus

A gas torus is a toroidal cloud of gas or plasma that encircles a planet. In the Solar System, gas tori tend to be produced by the interaction of a satellite's atmosphere with the magnetic field of a planet...

, a ring of air around a neutron star

Neutron star

A neutron star is a type of stellar remnant that can result from the gravitational collapse of a massive star during a Type II, Type Ib or Type Ic supernova event. Such stars are composed almost entirely of neutrons, which are subatomic particles without electrical charge and with a slightly larger...

. Its sequel is The Smoke Ring.

It was nominated for the Nebula Award

Nebula Award

The Nebula Award is given each year by the Science Fiction and Fantasy Writers of America , for the best science fiction/fantasy fiction published in the United States during the previous year...

 for Best Novel

Nebula Award for Best Novel

Winners of the Nebula Award for Best Novel, awarded by the Science Fiction and Fantasy Writers of America. The stated year is that of publication; awards are given in the following year.- Winners and other nominees :...

 in 1984 and the Hugo Award

Hugo Award

The Hugo Awards are given annually for the best science fiction or fantasy works and achievements of the previous year. The award is named after Hugo Gernsback, the founder of the pioneering science fiction magazine Amazing Stories, and was officially named the Science Fiction Achievement Awards...

 for Best Novel

Hugo Award for Best Novel

The Hugo Awards are given every year by the World Science Fiction Society for the best science fiction or fantasy works and achievements of the previous year. The award is named after Hugo Gernsback, the founder of the pioneering science fiction magazine Amazing Stories, and was once officially...

 in 1985.

Setting

The story is set at the fictional neutron star Levoy's Star (abbreviated "Voy"). The gas giant

Gas giant

A gas giant is a large planet that is not primarily composed of rock or other solid matter. There are four gas giants in the Solar System: Jupiter, Saturn, Uranus, and Neptune...

 Goldblatt's World (abbreviated "Gold") orbits this star just outside its Roche limit

Roche limit

The Roche limit , sometimes referred to as the Roche radius, is the distance within which a celestial body, held together only by its own gravity, will disintegrate due to a second celestial body's tidal forces exceeding the first body's gravitational self-attraction...

. Thus, Gold's gravity is insufficient to hold its atmosphere, which is pulled loose into an independent orbit around Voy. This orbiting air forms a ring known as the Gas Torus. The Gas Torus is huge—one million

Million

One million or one thousand thousand, is the natural number following 999,999 and preceding 1,000,001. The word is derived from the early Italian millione , from mille, "thousand", plus the augmentative suffix -one.In scientific notation, it is written as or just 106...

 kilometers thick—but most of it is too thin to be habitable. The central part of the Gas Torus, where the air is thicker, is known as the Smoke Ring. The Smoke Ring supports a wide variety of life.

There is no "ground" in the Smoke Ring; it is a world consisting entirely of sky. Thus, most animals can fly, even the fish. Furthermore, since the Smoke Ring is in orbit, it is in free fall

Free fall

Free fall is any motion of a body where gravity is the only force acting upon it, at least initially. These conditions produce an inertial trajectory so long as gravity remains the only force. Since this definition does not specify velocity, it also applies to objects initially moving upward...

. There is no "up" or "down". Most animals have trilateral symmetry, allowing them to see in all directions.

Most plants in the Smoke Ring are quite fragile, as they do not have to support their own weight. A notable exception to this rule are the eponymous Integral Trees. These are trees that are up to 100 kilometers long. Tidal locking

Tidal locking

Tidal locking occurs when the gravitational gradient makes one side of an astronomical body always face another; for example, the same side of the Earth's Moon always faces the Earth. A tidally locked body takes just as long to rotate around its own axis as it does to revolve around its partner...

 causes them to be oriented radially, with one end pointing in toward Voy and one end pointing out. The ends of the tree feel a tidal force

Tidal force

The tidal force is a secondary effect of the force of gravity and is responsible for the tides. It arises because the gravitational force per unit mass exerted on one body by a second body is not constant across its diameter, the side nearest to the second being more attracted by it than the side...

 of up to 1/5 g

G-force

The g-force associated with an object is its acceleration relative to free-fall. This acceleration experienced by an object is due to the vector sum of non-gravitational forces acting on an object free to move. The accelerations that are not produced by gravity are termed proper accelerations, and...

. Each end consists of a leafy "tuft", which is where photosynthesis occurs. Compared to trees on Earth, the tufts are both canopy and roots.

Each tuft of a tree is up to 50 kilometers from the tree's center of mass

Center of mass

In physics, the center of mass or barycenter of a system is the average location of all of its mass. In the case of a rigid body, the position of the center of mass is fixed in relation to the body...

. Thus, a tuft is either orbiting too slowly (the "in" tuft) or too quickly (the "out" tuft), compared to the atmosphere, which is in orbit at all points. The ends of the tree are subject to a constant hurricane-force wind. This wind bends the ends into the shape of an integral

Integral

Integration is an important concept in mathematics and, together with its inverse, differentiation, is one of the two main operations in calculus...

 symbol: ∫. The trees are "fed" by the constant inflow of materials to their tufts caused by water and food being blown into the tufts, or alternately onto the trunk, where the gravity-like tidal forces pull the material out towards the tufts.

The Smoke Ring was colonized 500 years prior to the beginning of the story by a crew of 20 astronauts on board an interstellar "ramship"

Bussard ramjet

The Bussard ramjet is a theoretical method of spacecraft propulsion proposed in 1960 by the physicist Robert W. Bussard, popularized by Larry Niven in his Known Space series of books, and referred to by Carl Sagan in the television series and book Cosmos....

. Their descendants have adapted to the free-fall environment by growing taller and developing prehensile toes. Small numbers of devices from the original crew are coveted items in the Smoke Ring society.

Plot setup

Quinn Tribe inhabits the "in tuft" of Dalton-Quinn tree. They normally subsist on the tree's cottony foliage, augmented by hunting and a flock of domesticated turkeys. But ever since the tree passed near Gold six earth years ago it has been falling in toward Voy, nearly dropping out of the Smoke Ring. As a result, the tribe is suffering from a severe drought. The tribe's leader, the Chairman, decides to send a party of nine up the tree, ostensibly to hunt and re-cut tribal markings into the trunk. The group consists mostly of cripples or people the Chairman dislikes, and including the Chairman's son-in-law, Clave, and Jeffer, the Scientist's apprentice.

Plot conflict

As they approach the mid-point they notice that the tribal markings are different. When the party reaches the midpoint of the tree, they are attacked by members of the Dalton-Quinn tribe living at the other end of the tree. During the battle a massive tremor splits the tree in half, causing the in tuft to fall farther in toward Voy (killing its inhabitants) allowing the out tuft to find a new equilibrium closer to the Smoke Ring's median. The seven surviving members of the Quinn Tribe and one of the attackers jump clear of the shattered tree, and are left adrift in the sky with only a few "jet pods" (high pressure seed cases that provide a temporary thrust when opened) as their only method of propulsion.

Before dying of thirst, they manage to hook a passing "moby" (a flying whale-like creature), which takes them to a "jungle", a floating mass of plant life. They cut loose and crash, and find themselves in the middle of a battle between the Carther States, who live in the jungle, and slave-runners from London Tree. The group is split when six of them are captured by the slavers; the other two remain in the jungle.

Plot resolution

Carther States counter-attacks some weeks later, and the Quinn Tribe group is reunited. During the battle they manage to steal the London Tree's CARM (Cargo And Repair Module), a miniature spacecraft, a relic of the original settlers. Not fully understanding how to pilot the CARM, they engage its main motor, which sends them thousands of miles away before running out of fuel. As a result, they become the first Smoke Ring inhabitants in centuries to see the naked stars.

Unknown to any of the inhabitants of the Smoke Ring, the ship their ancestors arrived in, Discipline, is still in orbit, and its AI

Artificial intelligence

Artificial intelligence is the intelligence of machines and the branch of computer science that aims to create it. AI textbooks define the field as "the study and design of intelligent agents" where an intelligent agent is a system that perceives its environment and takes actions that maximize its...

 autopilot, Kendy, is watching their progress. When Kendy sees the CARM dangerously far from the habitable area of the Ring he contacts them. With help from the on-board computer and after some interaction with Kendy, the occupants of the CARM eventually find their way safely back into the Smoke Ring. Unable to find their way back to any of the trees they know, they decide to settle on a new tree, which they dub Citizens Tree.

Awards and nominations

The Integral Trees won the 1985 Locus Award for Science Fiction novel

The Integral Trees was a nominee for the following awards

• 1985 Hugo Award for Best Novel
  Hugo Award for Best Novel
  The Hugo Awards are given every year by the World Science Fiction Society for the best science fiction or fantasy works and achievements of the previous year. The award is named after Hugo Gernsback, the founder of the pioneering science fiction magazine Amazing Stories, and was once officially...
  
  
• 1985 Nebula Award for Best Novel
  Nebula Award for Best Novel
  Winners of the Nebula Award for Best Novel, awarded by the Science Fiction and Fantasy Writers of America. The stated year is that of publication; awards are given in the following year.- Winners and other nominees :...
  
  
• 1985 Science Fiction Chronicle Reader Awards