Acrogen

noun

1. An aerogenous plant.
2. A plant of the highest class of cryptogams, including the ferns, etc. See cryptogamia.
3. the age of coal plants, or the carboniferous era.
4. any flowerless plant whose growth takes place at the tip of the main stem, especially the cryptogam ferns
5. any flowerless plant such as a fern (pteridophyte) or moss (bryophyte) in which growth occurs only at the tip of the main stem