Arboretum
The arboretum was a botanic garden with trees as its dominant feature. While arboretums were normally on planetary surfaces, they were built and found on board several Federation starship classes, like the  and . (; )

Although the arboretum was considered a recreation area where crewmembers could relax in a natural setting, it was also an area of scientific research. ()

Aboard the , the arboretum was on deck 17, section 21 alpha. It contained a number of different types of plant life, including Cypirion cactus and roses. There was also a small pond. ()

Civilians were allowed to staff positions in the arboretum. Keiko O'Brien was head of the plant biology lab while she was aboard the ship. The arboretum on the Enterprise was where Keiko's husband Miles asked to marry her. (; ) Children such as Clara Sutter were also allowed to help with small projects in the arboretum. ()

When the entire ship was affected by Barclay's Protomorphosis Syndrome, many of the crew were clustered in the arboretum. ()

In 2369, Vedek Bareil Antos told Commander Benjamin Sisko that he preferred the sanctity of his arboretum to listening to 112 vedeks for hours. ()

In 2370, the Enterprise-D arboretum took the place of Lake El'nar in Lwaxana Troi's mental recreation of the death of her daughter, Kestra, witnessed telepathically by Deanna Troi. () 

That same year, Major Kira Nerys visited the Bareil Antos' monastery on Bajor and spent time in the arboretum there, trying to repair the stone lining of a pond. It ended up rather crooked and she commented that she was sure she could destroy his entire arboretum if she stayed long enough. ()

In 2371, Odo spent some time in an arboretum after discovering his people's . () Later in that year and following his transfer to Deep Space 9, Miles O'Brien drew up plans to turn one of the station's cargo bays into an arboretum to cheer up Keiko, who missed being able to do botanical research. However, these plans were abandoned when Julian Bashir convinced Miles that an arboretum could only afford Keiko a mere hobbyist's level of research opportunities, when what she really craved was an extended field expedition. ()

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Background information 

Like the botany section aboard the , the arboretum was presumably part of the life sciences department.

The refit Enterprise seen in  appeared to have an arboretum in the lower part of its engineering hull, as trees were seen beyond the several large viewports on each side of the hull. This appears to be the original intention of designer Andrew Probert, and is confirmed in this image and many non-canon publications such as Mr. Scott's Guide to the Enterprise.

Some blueprints have identified the two large blue windows below the main shuttlebay on the Enterprise-D model as the arboretum windows, although the set had no such windows. It is possible there was more than one arboretum on the Galaxy-class. Also the arboretum is stated to be on Deck 17, however that was the ship's stardrive section, where most of the ship's essential functions were located. Blueprints produced by Rick Sternbach show the twin windows for the arboretum however interior blue prints do not show them.

External links
 
 

de:Arboretum
Spacecraft sections
Botany