Yggdrasil Bush, Yggy

Variant of the Orwood space tree

Yggdrasil Bush
Image from Steve Bowers
A mature Yggdrasil bush covering an irregular double-lobed asteroid

Variant species of the orwood biological space habitat.

Designed to thrive in vacuum or minimal atmosphere conditions, Yggdrasil bushes (or Yggys as they called colloquially) may be planted on any suitable body with at least 1/100G surface gravity. During its growth phase, the Yggdrasil bush mines minerals, atmospheric gases, and water out of the soil and stores them within its trunk. Using a portion of the stored gases, it ejects a set of seed packets from itself once every few weeks. Each bush broadcasts its position using bioluminescent cells on its trunk and leaves. When a sufficient number of bushes have accumulated, their bio-luminescent signals naturally form a primitive local network. The direction and trajectories of future seed packets are determined using data shared by this network in order to maximize plant growth and area coverage for the forest as a whole.
Yggdrasil Bush
Image from Steve Bowers
This immature Yggdrasil Bush only covers a fraction of the planetoid it is growing on; eventually the canopy will cover the entire object, and only then will the plant release atmospheric gases
The Yggdrasil bush grows to approximately a kilometer in height. When upward growth is complete, each bush begins to extend the growth of its canopy of leaves. Canopy growth continues until each bush has thoroughly intertwined its canopy with that of its neighbors. At this point the joined canopies fuse together into a tough, plastic-like sheath capable of holding integrity against standard atmospheric pressure. Completion of the canopy across the entire planetary surface triggers a reflex within the bushes, causing them to release the atmospheric gases and water stored during the growth phase. If insufficient volatiles are available on the parent body, they may be imported for the use of the bushes.

In the final phase of their growth, the Yggdrasil bushes alter their biochemistry to maintain and support the newly created atmosphere. Symbiotic soil gardening organisms are budded off of the bush root systems and the other basic elements of a self-sustaining ecosystem are a rapidly budded off from the bushes as well. Starting from a single seed, a complex of Yggdrasil bushes can convert an entire dead world into a living habitat in as little as twenty years.

There are various possibilities with the use of this versatile neogenic plant. Options include designing support pillars to look like giant trees, or using a variant of the dyson tree to cover a moon or planetoid in a huge forest with the canopy merging together to hold in an atmosphere. Yggdrasil bushes can be easily seeded on small ice moons and halo objects. Aleph Michio Ee adapted the Bluesky worldhouse to be photosynthetic, making the Greensky worldhouse... These involve an adaptation of the Yggdrasil bush with enough atmosphere to fly a light aircraft about without hitting the tree trunks.

Further, there is no real need for terraforming large worlds when you can bush up the icy asteroids- assuming you can gene out the low gravity space sickness effects reliably.

One popular variant is a Fucus vesiculosus - Bladderwrack - modification that can develop in Gas Giant rings, with a small (100-200m) bladder full of breathable air, sometimes with edible fruit and nuts growing on the inside. The bladders are loosely connected, with insulated flexible corridors between the bladders, and all the ice and rock of the rings incorporated into the spaceweed to avoid collision damage.

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Development Notes
Text by Todd Drashner and Steve Bowers
Initially published on 25 October 2007.