| ATH | a genus of gymnosperm |
|---|---|
| ATH | evergreen of Tasmanian mountains having sharp-pointed leaves the curve inward |
| ATH | at an oblique angle |
| ATH | at right angles to the center line of a ship |
| ATH | alternative names for one of a number of families into which the family Polypodiaceae has been subdivided in some classification systems |
| ATH | temperate and tropical lady ferns |
| ATH | a lady fern with deeply cut leaf segments |
| ATH | most widely grown fern of the genus Athyrium for its delicate foliage |
| ATH | North American fern with narrow fronds on yellowish leafstalks |
| ATH | fern with elongate silvery outgrowths enclosing the developing spores |