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The definitions here given are specific to the plants dealt with in this guide. Some have wider or different meanings in other botanical contexts (capsule, for example).
Abortive(Of spores): not completely developing and infertile.
AcroscopicFacing towards the apex (of frond or pinna).
AcuteAngle less than 90°.
AdnateAttached all along the base, usually applied to a leaf segment.
AlienIntroduced plant that has become established.
Anastomosing(Of veins): joining up to form a network.
AnnulusThe ring or line of thick-walled (indurated) cells on the sporangium that allows it to burst open when ripe (dehisc).
Antheridium; plural: antheridiaMale sex organ, on the underside of the prothallus, that produces sperm.
ApogamousFerns that reproduce asexually: the new plants (sporophytes) grow directly from the prothallus, not from a fertilized egg.
AppressedLying flat against.
Archegonium; plural: archegoniaThe female sex organ containing the egg.
AreoleArea enclosed by netted (anastomosing) veins.
AscendingCurving upwards.
AttenuateGradually tapering to a long thin point.
AuricleEar-like lobe at the base of a leaf.
AxilAngle between the main and side branches.
AxillaryIn the axil.
Axis; plural: axesThe primary or central part of of a plant or leaf to which the other parts are joined, eg the rachis or midrib.
Basal cellsCells in the sporangium, between the annulus and the top of the stalk. The number of these is a diagnostic character in Polypodium.
Basal sinusLowest sinus on a leaf.
BasiscopicFacing towards the base (of frond or pinna).
BipinnatePinnate with the pinnae also pinnate (also 2-pinnate, twice-pinnate); the secondary divisions are called pinnules.
Bipinnate-pinnatifidAs above, but with the pinnules divided again about half to three-quarters of the way to the midrib.
BladeMain part of the leaf or frond, excluding the stipe.
BulbilSmall bulb-like or bud-like body borne above the ground on a stem or leaf, which detaches to grow as a new plant - see Huperzia selago. (See also gemma).
CalcicoleA plant that prefers alkaline (base-rich) conditions ("lime-loving").
CalcifugeA plant that prefers acid (base-poor) conditions ("lime-hating").
CapsuleThe part of the sporangium within which the spores develop.
Clathrate(Of scales): having a latticed appearance under a hand-lens - the result of dark cell walls.
ConcolorousUniformly coloured.
ConeBranch tips bearing modified spore-bearing leaves (sporophylls) compressed together so they appear distinct from the other leaves; also known as a strobilus. Found in Horsetails and Clubmosses.
ConfluentRunning or merging together.
Contiguous(Usually of margins of leaf segments): touching each other or running alongside.
Cordate(Usually of the base of a frond or blade): heart-shaped.
CoriaceousLeathery in texture.
CostaMidrib of a pinna.
CrenateHaving rounded teeth.
CrozierThe young leaf forming a coil before it unfurls. (Often called a fiddlehead in the U.S.).
CuspidateNarrowing abruptly to a point.
Decumbent(Usually of rhizomes): prostrate or flat to the ground but with the tip turned up.
Decurrent(Of the frond or leaf-segment): having the base extend downwards along the axis.
Dehiscence (verb: to dehisc)Opening of the sporangium to release the spores.
DentateToothed, with the teeth pointing mostly outwards.
DenticulateFinely dentate.
DichotomousBranching in two.
DimorphicHaving two forms. Usually applied to fertile and sterile leaves of some ferns, eg Thelypteris, Osmunda.
DiploidWith two matching sets of chromosomes.
DissectedDeeply divided.
DistalFurthest away, usually referring to the part of leaf or leaf segment furthest way from the point of attachment.
DistantWidely spaced, far apart.
DivergentGrowing apart, spreading out.
Dorsiventrally flattenedFlattened to give an upper and a lower surface.
Entire(Of the margin of leaf): not toothed, lobed or divided.
EphemeralLasting only a short time; (of indusium): quickly shed.
EpiphyticGrowing on trees, using their bark or branches as support but not parasitic on them.
EuphyllophytesThe group containing both ferns (monilophytes) and seed-bearing plants (spermatophytes).
Eutrophic(Of lakes, ponds, etc.): rich in nutrients.
False indusiumAn indusium formed by the rolled-over margin of the leaf enclosing the sorus, as in Adiantum capillus-veneris.
FamilyTaxonomical division comprised of a group of related genera.
Fern alliesGroup of vascular plants traditionally thought to be closely related to ferns, based mainly on the spore-bearing characteristic. These comprise the families of horsetails (Equisetaceae), quillworts (Isoetaceae), clubmosses (Lycopodiaceae), whisk ferns (Psilotaceae) and spikemosses (Selaginellaceae). Recent research has shown quillworts, clubmosses and spikemosses to be much less closely related to ferns, while horsetails and whisk ferns are more closely related, in fact essentially part of the main fern grouping.
Free(Of veins): not joined at the ends.
FrondThe leaf of a fern, including the stipe.
GametophyteThe sexual generation of the fern developing from the spore, generally a small flattish plant (see prothallus). The sex organs (archegonia and antheridia) develop on this, and the fertilization of the egg by the sperm (antherozoid) produces the gamete which develops into the recognizable fern plant (sporophyte).
Gemma; plural: gemmaeA bud or bulbil that detaches from the main plant and develops into a new plant, as in Huperzia selago.
Genus, pl: generaTaxonomic division comprised of a group of related species.
GlabrousHairless and scaleless.
GlandAn organ that secretes a sticky and/or scented juice, usually on the surface of leaf or stem, appearing as a spot, a raised bump or the tip of a hair.
GlandularHaving glands.
GlaucousGreyish, blue-grey or whitish (often as a bloom on an otherwise green surface).
Globose; globularSpherical or nearly so.
HaploidWith a single set of chromosomes. This is characteristic of the gametophyte stage.
HeterosporousWith two types of spores: megaspores (female) and microspores (male), as in Isoetes and Selaginella.
HexaploidWith six sets of chromosomes.
HomosporousWith spores all of a single type, as in most ferns.
HybridCross between two different taxa. Usually between species, but subspecies may hybridise (see Nothosubspecies), and occasionally hybrids between species belonging to different genera occur.
ImbricateOverlapping, like roof tiles.
IncisedCut deeply.
Indurated cellsThe thickened cells of the sporangium making up the annulus.
Indusium; plural: indusiaMembrane covering the sorus, not always present, and often shed at some stage in the development of the sorus. See also false indusium.
InternodeThe part of the stem between nodes. Used of Equisetum.
IntroducedA plant that was brought into the country (either deliberately or accidently) by man.
LaminaThe leafy part of a frond, not including the midrib, rachis or stipe.
LanceolateLance-shaped: narrow, pointed, slightly wider below the mid-point of the leaf.
LatticedForming a mesh.
LeafFrond; used here to include both the "leafy" part and the stipe or stem.
Leaf-bladeThe "leafy" part of the frond excluding the stipe or stem.
Leaf-segmentAny subdivision of a frond. See pinna, pinnule, pinnulet.
LiguleSmall membrane at the base of the upper side of the leaf, found in Isoetes and Selaginella.
LinearLong, narrow and parallel-sided or close to.
LobeA clear division of a leaf or leaf segment but not so as to be completely cut to the midrib.
LycophytesThe group comprising quillworts, clubmosses and spikemosses. Distinct from both euphyllophytes, the group that contains both seed plants (spermatophytes) and ferns (monilophytes).
MegasporangiumThe sporangium bearing megaspores, in heterosporous plants - Sealaginella and Isoetes.
MegasporeThe female spores, usually relatively large, in heterosporous plants. These give rise to female gametophytes (archegonia).
MicronOne thousandth of a millimetre.
MicrosporangiumThe sporangium bearing microspores, in heterosporous plants - Sealaginella and Isoetes.
MicrosporeThe male spores, usually relatively small, in heterosporous plants. These give rise to male gametophytes (antheridia).
MidribCentral vein of a frond in simple fronds, or of a leaf-segment in divided fronds.
MonilophytesThe group comprising all ferns, now known to include horsetails and whisk-ferns; a recently-coined term to distinguish them from spermatophytes (seed-bearing plants).
MonoleteHaving a single rectilinear mark. Used of spores. The mark derives from the way the spore was attached to the other spores in the sporangium. Monolete spores are generally approximately bean-shaped; see also Trilete
MorphotypeAn intermediate taxonomic division (not formally recognized), generally used to describe forms at around species level or narrower, where the differentiation is not fully understood (as in Dryopteris affinis).
MucronateTerminating abrubtly in a short point.
NativeOccurring naturally, not introduced by man.
NaturalizedAn introduced plant that has become established and propogates itself naturally.
NodeThe point on a stem where leaves arise. Nodes are most clearly seen in horsetails.
Nothosubspecies, often abbreviated to nothosubsp., nothossp. or n-subsp.Hybrid where one or both parents is a subspecies (the term nothospecies is occasionally used to denote a hybrid between two species).
ObtuseAngle greater than 90°.
Oligotrophic(Of lakes, ponds, etc.): poor in nutrients.
OvateEgg-shaped (in two dimensions).
Paraphysis; plural: paraphysesSmall hairs, often branched, among sporangia; eg Polypodium cambricum.
PatentAt right-angles.
Peduncle(Of Clubmosses): the stalk of a cone.
PeltateHaving the stalk attached in the centre.
PersistentLasting a long time; (of indusium): remaining in place.
PetioleThe stalk of a leaf; usually referred to as a stipe in ferns.
Pinna; plural: pinnaePrimary division of a leaf. Pinnae are attached to the rachis by their midribs.
Pinna segmentDivision of a pinna, whether cut entirely to the midrib or not.
PinnateHaving the leaf divided once into distinct leaflets; like a double-sided comb (also 1-pinnate, once-pinnate). 2-pinnate = having the primary divisions are themselves pinnate (also bipinnate, twice-pinnate).
Pinnate-pinnatifidPinnate, with the pinnatifid pinnae (divided, but not all the way to the midrib).
PinnatifidHaving the leaf divided once into distinct divisions, but not cut all the way to the rachis, so not forming separate leaflets.
PinnatisectAs pinnatifid but cut almost all the way to the rachis.
PinnuleSecondary division of a leaf. Pinnules are disions of pinnae.
Pinnule segmentDivision of a pinnule, whether cut entirely to the midrib or not.
PinnuletTertiary division of a leaf. Pinnulets are divisions of pinnules.
PolyploidWith more than two sets of chromosomes.
ProcumbentLying flat along the ground.
ProthallusThe gametophyte stage of the fern. This is the independent stage where sexual reproduction takes place. In most ferns, it is a small, flattish, often roughly heart-shaped body.
ProximalClosest, usually referring to the part of leaf or leaf segment closest to the point of attachment.
PteridophyteTraditional term encompassing both ferns and "fern allies"; the latter now known to be composed of some groups which are essentially ferns but look unlike them, and others which are not at all closely related. See Lycophytes, Monilophytes, Euphyllopytes.
PubescentCovered in small fine hairs.
Rachis (also rhachis); plural: rachides or rachisesThe section of midrib within the leafy part of the frond, ie above the stipe.
ReceptacleThe part of the frond to which the sorus is attached; often raised slightly above the surface.
ReflexedBent backwards or downwards.
Reticulate(Usually of veins): forming a network.
RhachisSee rachis
RhizomeStem of the fern plant, as opposed to the stem of an individual leaf which is called a stipe. In ferns, this is is often partially hidden, indistinct or partially underground. It may be creeping, as in Polypodium, or upright and highly visible as in tree-ferns.
ScaleSmall, often semi-transparent outgrowth of the outer layer of cells (epidermis). Usually most frequent towards the lower part of the stipe. Must be at least two cells wide to qualify as a scale - if only one cell wide it's a hair. Dicksonia species, for example, have hairs instead of scales.
ScariousThin, dry-looking, translucent, often whitish.
SimpleNot divided. Applies to a whole leaf, as opposed to entire.
SinusThe gap or indentation between teeth or lobes of frond.
SorusA cluster of sporangia.
SpeciesTaxonomic division generally used to describe those plants that will interbreed freely with each other and share a range of visual similarities. There is, however, no precise, universally agreed definition.
SpermatophytesSeed-bearing plants.
SpinoseWith spines.
SpinuloseWith small spines.
Sporangium; plural: sporangiaThe spore case; capsule containing spores. A group of sporangia make up a sorus.
SporeThe minute, single-celled body which develops in the sporangium. When released it germinates and develops into the gametophyte.
SporelingTiny fern plant still attached to the gametophyte from which it has developed.
SporocarpA globose structure that contains the sporangia in Pilularia.
SporophyllFertile leaf that carries the sporangia in clubmosses.
SporophyteThe generation of the fern that produces the spores. This is the main visible plant that is normally thought of as the actual fern. See gametophyte.
StipeStalk of the leaf, ie the part of the midrib below the leafy part or blade.
StolonRunner from the main stem, producing a new plant that roots independently.
Strobilus; plural: strobiliThe cone. Branch tips bearing modified spore-bearing leaves (sporophylls) compressed together so they appear distinct from the other leaves. Found in Horsetails and Clubmosses.
Subspecies, often abbreviated to spp. or subsp.Subdivision of a species.
Taxon; plural: taxaAny members of a specific taxonomic grouping, eg species, genus, etc. So one may refer to the Asplenium trichomanes and Asplenium ruta-muraria taxa (species); Dryopteris and Polystichum taxa (genus); or the Lycopodiacae and Selaginellaceae taxa (family).
TerminalAt the tip.
TerrestrialGrowing on the ground.
TetraploidWith four matching sets of chromosomes.
ToothSmall lobe.
TransverseAt right angles; cross-ways.
TrileteHaving a distinct Y-shaped mark. Used of spores. The mark derives from the way the spore was attached to the other spores in the sporangium; see also Monolete
TripinnatePinnate with the pinnae and pinnules also pinnate (also 3-pinnate, thrice-pinnate).
TriploidWith three matching sets of chromosomes.
Ultimate segmentThe final, smallest divisions of a leaf.
Variety, often abbreviated to var.Subdivision of species, but less well-defined that a subspecies.
VeinStrands of vascular tissue, normally visible in leaves.
VenationThe pattern formed by the veins in the leaf.
VerrucoseCovered in small warts.
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