FrankenTrees

* See also Rapture_Air
* See also Rapture_Agriculture
* See also Arcadia
* See also Langford
Trees seen on the Arcadia level, on display in some odd (expensive) enclosures out in the Ocean - likely those really were advertisement exhibits. ( Forests of substantial size would be elsewhere. )
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Genetically ADAM-Modified Trees used to generate Oxygen ( and recycle Carbon Dioxide out of the air ) to make Rapture's environment livable. You would expect something more efficient than replacing air by pumping from the Ocean's surface, or other energy/chemical expensive processes. Byproducts are wood and biomatter.
Developed in a project headed by Dr Julie Langford for Andrew Ryan.
NOTE - BEFORE ADAM existed in Rapture ( before 1952 ), the same function would have to be done by ordinary trees ( and plants on Farms or drawing air down from the Surface ).
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Note - Rapture's many large FARMS would do far more in supplying Rapture with Oxygen. Plantations of such trees, to be cost effective, would have to be grown densely ( more likely a dwarf variety would prove worthwhile ). Having them in planters in the Public spaces of Rapture might be a good idea ( and maybe seen in Flashbacks in the MMORPG ). Tanks full of circulated algae, being bombarded with ultraviolet lamps would be far more efficient for scrubbing CO2 ( something considered for long Space Missions ). 
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Dr Langford would keep developing improvements in her Laboratory.
Quick growing Wood-producing trees would be a marketable industry.
Improved/efficient lighting methods (fluorescent light) would be an important component (NOTE - the picture doesn't show particularly bright lighting which real Trees need)
A potential recycling use for some City sewage 'nutrients'.
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