fern
Enable an AI agent to recognise a fern, assess its life stage and condition, and choose care, propagation or handling actions appropriate to its identity and setting.
Research draft, second pass
A second pass drafted this model: the structure a model of this thing needs, and what is known about it in the world. The line under this one says how the second half was obtained - researched against sources, or recalled without web access, in which case nothing here was read anywhere and every claim is a lead to verify. Unreviewed either way.
Researched by: Codex + Grok
Purpose and description
Enable an AI agent to recognise a fern, assess its life stage and condition, and choose care, propagation or handling actions appropriate to its identity and setting.
A fern is a spore-dispersing vascular plant of class Polypodiopsida whose typical vegetative organ is a megaphyllous frond that uncoils by circinate vernation, with a free-living gametophyte and no seeds; under the Pteridophyte Phylogeny Group system this clade also includes horsetails and whisk ferns.
It can be Inspect and photograph diagnostic frond and reproductive structures with minimal disturbance.; Track marked fronds and crowns to assess growth, damage and seasonal change.; Adjust watering, drainage, light or humidity using identity-specific evidence.; Repot, remount or relocate a fern after assessing its growth habit and root or rhizome condition.; Evaluate division or spore propagation when identity, maturity and collection permission support it.; Remove confirmed dead tissue or isolate a symptomatic cultivated specimen when justified by observations..
Distinguishing features
Check reproductive structures: a flowering or seed-bearing plant sold under a fern-like common name requires reassessment; absence of flowers alone does not establish fern identity.
Where present, inspect sporangia and their arrangement, including sori or specialised fertile structures; distinguish organised reproductive structures from lesions, eggs or attached pests.
Examine frond attachment, venation, division and stem or rhizome characters together; a feathery leaf shape alone cannot distinguish a fern from a flowering look-alike.
Record whether emerging fronds uncoil as fiddleheads, but do not require this character or treat it as sufficient identification by itself.
For a small thallus-like specimen, seek reproductive characters, associated young sporophytes or expert evidence before identifying it as a fern gametophyte rather than a bryophyte or other growth.
Scope
+ Identification supported by frond, stem and reproductive characters
+ Boundaries of an individual, crown, rhizome-connected clump or gametophyte
+ Frond development, seasonal behaviour and reproductive state
+ Water, light, temperature and growing-medium compatibility
+ Condition assessment and suitability for care or propagation
- Whole woodland, wetland or other habitat dynamics
- Soil, substrate and water bodies as independent things
- Plant pathogens and herbivores as independently modelled organisms
- Containers, irrigation systems and greenhouse equipment
- Commercial nursery inventories and transactions
Characteristics
- Identification and supporting evidence
- Candidate taxon or unresolved fern; confidence; observed diagnostic characters Care requirements and interpretation of structures depend on identity.
- Life-cycle stage
- Gametophyte, juvenile sporophyte, mature sporophyte, mixed or unresolved Different stages require different recognition criteria and interventions.
- Growth habit
- Terrestrial, epiphytic, rock-associated, aquatic or unresolved; creeping, clumping or trunk-forming where applicable Habit constrains suitable placement and interpretation of roots and stems.
- Connected growth boundary
- Observed or suspected connection between fronds, crowns, rhizomes and neighbouring growth Connected growth affects individual recognition and the consequences of division.
- Frond dimensions
- Frond length and maximum width in cm, with developmental stage Comparable measurements support identification and growth assessment.
- Frond cohort condition
- Emerging, expanding, mature, senescing or dead; colour, turgor and damage by cohort The distribution of symptoms helps distinguish ageing from active decline.
- Reproductive structures
- Absent, present or unexamined; location, arrangement and apparent maturity Reproductive structures aid identification and propagation decisions.
- Root-zone moisture
- Method-labelled moisture reading or wetness class, with depth and observation time Watering decisions require evidence from the growing medium as well as the fronds.
- Light exposure
- PPFD in µmol m⁻² s⁻¹ where available; direct-sun duration in hours per day Measured exposure supports assessment against the identified fern's requirements.
- Microclimate
- Temperature in °C and relative humidity in %, including observed range and duration Exposure history helps interpret stress and select placement.
Also called
Where this came from
wikidata · CC0 1.0
Also registered as vr.tr.fern
Drafted structure
Bundle to layer to finding to question, as the second pass will find it: 6 bundles · 11 layers · 18 findings · 28 questions.
Fern recognition Establish whether the organism is a fern and how precisely it can be identified.
Common names and fern-like foliage can mislead an agent into applying inappropriate care.
Vegetative evidence
Assess frond and stem characters without relying on overall resemblance.
Diagnostic character combination
Record the combination of visible characters supporting or contradicting the proposed identity.
- What frond division, venation, stipe, scale or hair characters and stem features are observable? definition
- Which identification key or expert determination supports the candidate identity, and which characters remain unchecked? provenance
Fertile structure evidence
Use reproductive structures to refine identification and resolve look-alikes.
Sporangia versus look-alikes
Document suspected reproductive structures and the evidence distinguishing them from damage or attached organisms.
- Where are suspected sporangia located, how are they arranged, and are coverings or specialised fertile fronds visible? definition
- What observation would distinguish these structures from scale insects, eggs, lesions or other look-alikes? boundary
Organism boundary and life cycle Identify the unit being assessed and its developmental and reproductive stage.
A frond, connected clump and gametophyte require different interpretations and handling.
Connected growth
Establish how visible fronds and crowns relate to stems and neighbouring growth.
Assessment unit
Define a practical observation unit without assuming that nearby fronds are separate organisms.
- Which fronds arise from the same visible crown, rhizome or trunk, and which connections are only suspected? boundary
- Would lifting, cutting or dividing this unit disturb growth beyond the intended specimen? action
Development and reproduction
Record life-cycle stage and evidence of reproductive readiness.
Stage and fertility
Separate developmental identity from the current presence of fertile structures.
- Is the observed organism a gametophyte or sporophyte, and what evidence supports that assessment? definition
- What evidence shows whether fertile structures are immature, releasing spores, spent or of unresolved maturity? measurement
Growing-site compatibility Assess whether the fern's placement supports its particular growth habit and requirements.
Fern care cannot safely assume a single moisture, shade or substrate preference.
Root and rhizome environment
Assess attachment, medium, moisture and drainage around the structures sustaining growth.
Medium and water fit
Relate observed growing conditions to requirements established for the identified fern.
- What supports the roots and rhizome, and how do wetness and drainage change between watering or rainfall events? measurement
- What taxon-specific evidence supports the current attachment, planting depth and moisture regime? provenance
Frond microclimate
Characterise light and atmospheric exposure at the fern rather than at a distant reference point.
Exposure fit
Record exposure patterns relevant to frond function and stress.
- What light, temperature, humidity and drying-air exposure reach the fronds over a representative day? measurement
- Which measured conditions fall outside documented tolerances for the candidate taxon and life stage? boundary
Frond and crown condition Assess the fern's condition through growth patterns and the location and progression of symptoms.
Old-frond loss, reproductive structures and seasonal changes must be distinguished from damaging processes.
Frond cohort dynamics
Compare emerging, mature and ageing fronds through time.
Growth versus decline
Record whether frond replacement and loss are compatible with the fern's expected seasonal behaviour.
- How many fronds are emerging, expanding, mature or dying, and how has that distribution changed? measurement
- What evidence distinguishes expected seasonal frond loss from abnormal decline in this fern? boundary
Symptom location and progression
Locate symptoms across fronds, growing points and accessible below-ground structures.
Stress evidence
Describe symptoms and competing explanations before selecting treatment.
- Where are discolouration, wilting, tissue loss or softening occurring, and how quickly are they spreading? measurement
- What additional inspection would discriminate among moisture stress, exposure injury, physical damage and a pest or pathogen? action
Care and propagation decisions Choose and evaluate interventions using fern identity, growth structure and current condition.
Division, spore collection and changes to placement can fail when applied without regard to fern biology.
Care intervention
Connect a proposed care change to observations and a measurable response.
Targeted care change
Specify the evidence, intended benefit and follow-up for an intervention.
- Which observed condition justifies changing watering, exposure, medium or placement, and what taxon-specific guidance supports the change? action
- Which changes in new-frond development, turgor or symptom progression would indicate improvement or deterioration, and over what interval? measurement
Propagation and collection
Assess whether division or spore-based propagation is appropriate and permitted.
Propagation readiness
Establish a supported propagation route and its constraints before removing material.
- Does this fern have growth suitable for division or mature spores suitable for collection, and what evidence supports the proposed method? action
- What ownership, collection or conservation restrictions apply to removing this specimen or its reproductive material? boundary
Evidence and external alignment What the world already says about this thing, gathered so the model can be checked against it.
A model that cannot be lined up against existing standards, identifiers and practice cannot be adopted by anyone who already uses them.
Reported evidence
Findings from the breadth pass, kept separate from the structural claims.
Kinds and varieties
Reported by the breadth pass; each item needs checking against its source before it becomes normative.
- leptosporangiate (polypod) ferns, the bulk of living species
- tree ferns (Cyatheales and some other arborescent lineages)
- filmy ferns (Hymenophyllaceae)
- aquatic and floating ferns (Salviniales, including Azolla, Salvinia and Marsilea)
- climbing ferns (notably Lygodium)
- eusporangiate marattioid ferns
- ophioglossoid ferns (adder's-tongues, moonworts, grape ferns)
- horsetails and whisk ferns, nested in ferns in current phylogeny but still often named separately in the field
- Which of these kinds and varieties hold for the sense of fern this model covers, and on what evidence? provenance
Identifiers and schemes
Reported by the breadth pass; each item needs checking against its source before it becomes normative.
- Wikidata - Q80005 - Item for fern as a taxon; narrower items exist for Polypodiopsida, Polypodiophyta and vernacular groups.
- PPG I - class Polypodiopsida - Community classification for extant ferns (including Equisetidae and Psilotales).
- International Code of Nomenclature for algae, fungi, and plants - generic and specific epithets with author citation (e.g. Pteridium aquilinum (L.) Kuhn) - Nomenclatural authority for scientific names; no single code number names 'fern' as a class.
- CITES - Appendix II listings for Cyathea spp. and Dicksonia spp. (and selected other tree-fern taxa) - Trade identifier for regulated arborescent ferns, not for the clade as a whole.
- Which of these identifiers and schemes hold for the sense of fern this model covers, and on what evidence? provenance
Standards and regulation
Reported by the breadth pass; each item needs checking against its source before it becomes normative.
- PPG I (Pteridophyte Phylogeny Group, 2016) - community standard for extant fern classification
- International Code of Nomenclature for algae, fungi, and plants (Shenzhen/Madrid Code) - IAPT / IBC
- CITES Appendices - CITES Secretariat, for international trade in listed tree ferns
- IUCN Red List of Threatened Species - IUCN, for conservation status of individual fern taxa
- National noxious-weed and biosecurity lists (e.g. USDA federal noxious weeds for Salvinia molesta; equivalent lists in Australia and New Zealand) - national plant-health authorities
- Food-safety advice on edible fiddleheads (ostrich fern and allies) - national food agencies such as Health Canada
- Which of these standards and regulation hold for the sense of fern this model covers, and on what evidence? provenance
Real-world use
Reported by the breadth pass; each item needs checking against its source before it becomes normative.
- Ornamental horticulture (Boston/sword ferns, maidenhairs, staghorns, tree ferns in shaded gardens and interiors)
- Seasonal wild food: tightly coiled croziers ('fiddleheads'), especially Matteuccia struthiopteris in northeastern North America and Japan
- Azolla cultivated in Asian rice systems as a nitrogen-fixing green manure (via its Anabaena/Nostoc symbiont)
- Phytoremediation: Chinese brake (Pteris vittata) hyperaccumulates arsenic
- Craft and horticultural fibre from tree-fern trunks (historically including Hawaiian Cibotium and Dicksonia liners)
- Invasive aquatic mats (giant salvinia, some Azolla) managed as weeds in warm waterways
- Palaeobotanical and coal-measure fossils of Carboniferous tree ferns and seed-fern associates used in stratigraphy and as a deep-time analogue, not as living crop
- Which of these real-world use hold for the sense of fern this model covers, and on what evidence? provenance
Typical measurements
Reported by the breadth pass; each item needs checking against its source before it becomes normative.
- accepted living species in the clade - about 10,500-12,000 - species
- frond length - about 1-500 (filmy ferns at the low end; Angiopteris and large tree-fern fronds at the high end) - cm
- tree-fern caudex height - 2-20 - m
- haploid chromosome number (n) - about 20 to >700 (Ophioglossum among the highest counts in plants) - chromosomes
- spore diameter - about 20-60 (with outliers in heterosporous water ferns) - µm
- Which of these typical measurements hold for the sense of fern this model covers, and on what evidence? provenance
Failure modes and hazards
Reported by the breadth pass; each item needs checking against its source before it becomes normative.
- Bracken (Pteridium) contains ptaquiloside: associated with enzootic haematuria and cancers in grazing livestock and with thiamine deficiency; human dietary exposure is a documented concern where croziers or rhizomes are eaten
- Undercooked ostrich-fern fiddleheads have caused outbreaks of gastrointestinal illness
- Giant salvinia (Salvinia molesta), some Azolla, and Old World climbing fern (Lygodium japonicum / L. microphyllum) form dense mats or blankets that smother native vegetation and clog waterways
- Unsustainable harvest of slow-growing tree ferns for horticulture and fibre
- Occupational and indoor exposure to abundant spores can aggravate respiratory allergy
- Habitat loss and over-collection drive decline of narrowly endemic filmy ferns, tree ferns and limestone taxa
- Which of these failure modes and hazards hold for the sense of fern this model covers, and on what evidence? provenance
Regional variation
Reported by the breadth pass; each item needs checking against its source before it becomes normative.
- Edible 'fiddlehead' in eastern North America and Japan is usually ostrich fern; other regions eat different genera (including bracken in parts of East Asia), so the food name does not map to one species
- Tree ferns are a conspicuous forest element in wet tropics, Australasia and oceanic islands, and are almost absent as wild landscape plants in continental temperate Europe
- Nardoo (Marsilea drummondii) is a named staple and cautionary food plant in inland Australia, not a widely used category elsewhere
- Bracken is treated as a pastoral weed and public-health issue in the British Isles and New Zealand, and as a traditional food plant in parts of Japan and Korea
- English 'fern' in older European floras often excluded horsetails; PPG I and many herbaria now place Equisetum inside ferns, so checklist counts are not comparable across eras
- Which of these regional variation hold for the sense of fern this model covers, and on what evidence? provenance
Neighbouring kinds and how to tell them apart
Reported by the breadth pass; each item needs checking against its source before it becomes normative.
- lycophytes (clubmosses, spikemosses, quillworts) - Lycophytes have microphylls and a different deep phylogeny; ferns have megaphylls (fronds). Horsetails look leafless-jointed but are ferns, not lycophytes.
- mosses and other bryophytes - Bryophytes lack lignified vascular tissue and a sporophyte-dominant life cycle; fern sporophytes are vascular and usually the conspicuous generation.
- cycads - Cycad leaves can resemble large fern fronds, but cycads bear seeds in cones and never sori; fertile organs (cones versus spore heaps) separate them at a glance.
- palms - Palms are flowering plants with inflorescences and fruit; tree ferns have a fibrous caudex, circinate croziers and sori, never flowers.
- seed ferns (pteridosperms, fossils) - Foliage can be fern-like, but ovules/seeds are present; living ferns are free-sporing and seedless.
- Which of these neighbouring kinds and how to tell them apart hold for the sense of fern this model covers, and on what evidence? provenance
Sources
- A community-derived classification for extant lycophytes and ferns - Circumscription of Polypodiopsida, inclusion of horsetails and whisk ferns, and the named subclasses and orders used as kinds.
- A classification for extant ferns - Pre-PPG familial classification still used in herbaria and floras; morphology of leptosporangiate versus eusporangiate lineages.
- Plants of the World Online - Accepted names, distribution, and current placement of genera commonly treated as ferns.
- CITES Appendices I, II and III - International trade controls on tree ferns (Cyathea and Dicksonia, among others).
What the second pass must settle
- Does the registry intend fern to include all lineages treated as ferns by its chosen taxonomic authority, including horsetails and whisk ferns?
- Should independently observed gametophytes use this same model throughout, or require a specialised linked model?
- What operational rule should distinguish an individual from a rhizome-connected clump when genetic identity is unknown?
- Which authoritative references will supply taxon-specific environmental tolerances, seasonal behaviour and propagation requirements?
- Should ingestion and animal-exposure decisions be handled by a linked toxicity model, and what species-level evidence would that require?