| acroscopic | | on the side towards the apex of the frond |
| adnate | | in ferns, usually refers to the base of a pinnule being joined along its length to the midrib, rather than being stalked. May be 'half-adnate' or any other fraction. |
| annulus | | a row of cells with thickened walls on the sporangium, which contracts to tear the sporangium open, then springs back to throw the spores out. |
| auricle | | a small, usually rounded, lobe - literally 'a small ear' |
| basiscopic | | on the side towards the base of the frond |
| bi-pinnate | | twice divided (see pinnate) |
| costa | | the midrib of a pinna |
| crozier | | the coiled young fern frond (see Parts of a Fern) |
| dimorphic | | having two different forms - in ferns this means that the vegetative fronds differ from the fertile, spore-bearing fronds |
| eglandular | | without glands |
| entire | | not toothed or lobed |
| frond | | the leaf of a fern that arises from the rhizome |
| gamete | | a male or female sex cell, usually with one set of chromosomes |
| gametophyte | | a tiny plant that germinates from the spore and carries the gametes |
| gland | | an organ that produces secretions. In ferns, these often look like minute drumsticks. When the glands on the surface of a frond are very dense, they can give the frond a greyish, or mealy appearance. See pictures below. |
| glandular | | having glands |
| indusium | | a membrane that covers the sporangia |
| inflexed | | abruptly bent inwards |
| lamina | | the leafy part of a fern frond, above the stipe, or stalk |
| lanceolate | | shaped like a lance or spear head, tapering to both ends but wider nearer the base |
| lobe | | a section of an organ, usually rounded |
| ovate | | egg-shaped, with the broadest part nearer to the base |
| oblanceolate | | shaped like a lance, but with the broadest part nearer to the apex |
| obovate | | egg-shaped, but with the broadest part nearer to the apex |
| pinna | | the first division of a fern frond |
| pinnate | | once divided, for example in ferns, Polypodium or Blechnum. Twice divided fronds are bi-pinnate, e.g. common male fern, and three-times divided are tri-pinnate, e.g. broad buckler fern. |
| pinnule | | the first division of a pinna |
| pinnulet | | the first division of a pinnule |
| prothallus | | (plural prothalli) and the gametophyte plant. See Life Cycle diagram |
| rachis | | the midrib of the lamina in ferns, the axis of a compound leaf or inflorescence in angiosperms |
| rhizome | | a modified stem, which may be root-like, from which the fronds and true roots emerge. Rhizomes may be creeping, above or below ground, or they may be upright. |
| scale | | a membranous, leaf-like structure, can be present on the rhizome, stipe, rachis, costa, and sometimes on the under-surface of the lamina |
| sorus | | (plural sori) a collection of sporangia. Usually on the under-surface of the frond, but may be on the ends of fronds, as in the royal fern Osmunda regalis. Sori may be naked, or covered by an indusium. |
| sporangium | | the organ where spores are produced |
| spore | | the reproductive unit in ferns |
| sporophyte | | the alternate generation to the gametophyte , the conspicuous fern that bears spores |
| stipe | | the stalk of the frond, from the rhizome to the start of the lamina |
| tooth | | a small pointed projection on the edge of the leaf |
| tri-pinnate | | three-times divided |
| truncate | | appearing cut-off, usually at the base of the lamina. The opposite of tapering, when the size of the pinnae reduces progressively towards the base. |
