Botanical names and taxon scope
A taxon is a hypothesis about a group of organisms, such as a species or genus. A name is a regulated way of referring to that group. Botanists may agree that two populations are closely related but disagree on whether they belong to one species. They may also recognize the same species but transfer it to another genus after the understanding of relationships changes. [Turland et al. 2025] [2-WWW]
Nomenclatural rules do not themselves determine taxon boundaries. They ensure that once a particular treatment is adopted, the correct name, authorship, nomenclatural type and priority can be established. The 2025 Madrid Code is the current edition of the International Code of Nomenclature for algae, fungi, and plants. [Turland et al. 2025] [2-WWW]
In the atlas, genus and species are checked in Plants of the World Online. Higher classification follows the 2025 paper by de Vos and co-authors. These sources serve different functions. POWO maintains an updated framework of species names, while the phylogenomic publication proposes a classification of the whole family based on hundreds of genes. [Turland et al. 2025] [2-WWW]
Binomial names and author names
A species name consists of a genus name and specific epithet. In Opuntia fragilis, the first element identifies the genus and the second distinguishes the species within it. Both are italicized. The names of the authors of the name are not part of the binomial and do not require italics. [Turland et al. 2025]
The form Opuntia fragilis (Nutt.) Haw. also conveys history. Parentheses indicate that the first author described the taxon under another genus name, and the later author made the current combination. The epithet was retained because transfer to another genus does not describe a new species. The original name on which the combination was based is the basionym. [Turland et al. 2025]
Author abbreviations are standardized. They should not be expanded by guesswork or have parentheses removed to simplify a scientific label. A species name often suffices in an everyday collection, but when documenting changes, authorship helps distinguish similar names and find the correct nomenclatural publication. [Turland et al. 2025]
Nomenclatural type
A species name is permanently linked to its nomenclatural type. The type need not be the most attractive, most average or best-preserved individual. It is the reference point for using the name. When researchers later draw species boundaries differently, they ask, among other questions, which portion of the material studied contains the type. [Turland et al. 2025]
This distinguishes nomenclature from morphological description. Changed knowledge of variation may broaden or narrow a taxon without changing the type specimen itself. If two formerly named species are united, the choice of accepted name usually follows the priority of a correctly published, legitimate name. The Code nevertheless allows conservation or rejection of names when nomenclatural stability requires it. [Turland et al. 2025]
A collection plant does not become a type by matching an illustration. Identification should rest on traits, provenance and comparison with taxonomic accounts. A photograph can help, but does not replace fruit, seed and flower traits or population data when they are needed in the group concerned. [Turland et al. 2025]
Synonyms and name history
A synonym is not simply an incorrect name. Homotypic synonyms are based on the same type and often arise when a species moves between genera or changes rank. Heterotypic synonyms have different types but are treated as referring to one species in a particular taxonomic concept. [Turland et al. 2025] [2-WWW]
Opuntia imbricata and Cylindropuntia imbricata share the same nomenclatural history following a genus change. Uniting names based on different types requires a taxonomic decision about species boundaries. A synonym list should therefore have a source and date, rather than be copied endlessly from catalogue to catalogue. [Turland et al. 2025] [2-WWW]
Species cards retain selected former names useful for interpreting labels. The accepted name comes first, and a synonym is not presented as an equally current name. An older label should be retained in the documentation rather than discarded. It records the name under which the plant was acquired and may help recover provenance data. [Turland et al. 2025] [2-WWW]
New combinations and changing genus concepts
A new combination reflects a classification change, not a sudden change in a specimen's properties. When material known as Opuntia imbricata is treated as Cylindropuntia imbricata, its structure, provenance and tolerances do not arise anew. Updating the name helps link the species to the correct lineage and more recent literature. [Sánchez et al. 2022] [Turland et al. 2025]
Authoritative sources may differ. POWO currently accepts Pelecyphora vivipara, while de Vos and co-authors retain Escobaria and Pelecyphora as separate genera in their family classification. The portal makes this difference explicit. It uses the name accepted by POWO on the card and gives the alternative treatment and source in the commentary. [Sánchez et al. 2022] [Turland et al. 2025]
A name should not be selected for its familiarity. State the basis for the decision and allow searches by synonym. Field numbers, locations and material sources are especially valuable in a collection. These data remain useful even if the genus name changes several times. [Sánchez et al. 2022] [Turland et al. 2025]
Ranks below species and cultivated plant names
Subspecies and botanical variety are nomenclatural ranks referring to variation recognized in nature. Form has been used for finer variants, but its meaning depends on the particular treatment. Not every different spine or flower colour merits formal rank. [Turland et al. 2025] [Fleischer and Schütz 1978]
A cultivar belongs to the nomenclatural system for cultivated plants. Its epithet is written in upright type within single quotation marks after the botanical name, as in Gymnocalycium ‘Fancy’. A vegetatively propagated clone may be valuable horticultural material without botanical rank. Trade designations and names of informal forms should not automatically be added as taxonomic synonyms. [Turland et al. 2025] [Fleischer and Schütz 1978]
A hybrid is written with a multiplication sign when its origin is known and properly described. Intermediate appearance alone does not demonstrate hybrid origin. In the atlas, cultivated names and hybrid hypotheses should be distinguished from names accepted for wild species. [Turland et al. 2025] [Fleischer and Schütz 1978]
Procedure for updating a label
First transcribe the existing name, field number, seller or donor and acquisition date exactly. Then check the name in an updated taxonomic database. Record the accepted name, authorship and direct record link. Move the former spelling to the synonym or old-label field without removing the history. [2-WWW] [Turland et al. 2025]
If sources differ, record both treatments. Do not resolve disagreement by choosing the name used in more online shops. Check the revision publication and the scope of its material. For plants without provenance, retain a degree of uncertainty, such as genus-level identification or a comparative qualifier, rather than forcing a species identification. [2-WWW] [Turland et al. 2025]
As of 8 October 2026, the names of all fourteen atlas species remain accepted in POWO. Ranges on the cards come from Kew records. The date matters because the database is updated. The portal retains synonyms as an index to older literature, not as a decorative list of names. [2-WWW] [Turland et al. 2025]
Searching for names in sources
Begin searching with the full spelling of the name and its authorship, then repeat with the basionym and important synonyms. An older publication may lack the current combination despite describing the same biological material. Conversely, an identical epithet used in two genera is insufficient to establish the same taxon. [Korotkova et al. 2021] [2-WWW]
Save a database result with the check date and a persistent record address. A search-results list alone does not distinguish an accepted name, synonym, illegitimate name or misapplication. When citing a revision, give the name used by its author and the modern equivalent so the reader can trace the route from older literature to the current atlas card. [Korotkova et al. 2021] [2-WWW]
Meaning of name elements
A name may retain information about a shape, colour or organ that caught the describer's attention. The comparisons below develop five tables from the archival site. Similar roots were combined, explanations made consistent and traits previously treated as equivalent separated. Examples of elements and epithets help teach the language of descriptions. They are not a list of currently recognized species. [8-WWW]
Latin adjective endings change with the grammatical gender of the name, so grandiflorus, grandiflora and grandiflorum convey the same basic trait. Greek roots are sometimes Latinized, as akantha becomes -acanthus. The meaning of the entire name still needs checking in the original description. Literal translation is not an identification key. [8-WWW]
Growth habit and general plant appearance
| Element or term | Meaning | Examples and explanation |
|---|---|---|
| phyton | Plant, an element of Greek origin | Astrophytum combines a reference to a star with the term for a plant. Conophytum is an example outside Cactaceae. |
| stēlē, columna | Column or pillar | chrysostele, albicolumna. stēlē comes from Greek, columna from Latin. |
| dendron, arbor | Tree | arborescens means becoming tree-like. The element dendro- is Greek. |
| dumus | Shrub or scrub | dumetorum refers to scrub as a habitat and need not describe the cactus's own habit. |
| frutex | Shrub | fruticosus, frutescens indicate a shrubby character or its development. |
| virgultum | Shrub, scrub, young shoots | virgultus should be read in the context of the original description. |
| sphaira, globus | Sphere | sphaerocarpus applies globose shape to a fruit, globularis to a spherical shape. Not every element refers to the entire plant. |
| clava, korynē, rhopalon | Club | clavatus, claviformis, corynodes. They describe broadening towards the end of an organ. |
| cylindrus, kylindros | Cylinder | cylindroarticulatus means cylindrically segmented. The element also occurs in Cylindropuntia. |
| discus | Disc, shield | disciformis means disc-shaped. Discocactus illustrates the element's use in a genus name. |
| caespes | Turf, dense clump | caespitosus means clumping, forming clusters of shoots. |
| depressus | Flattened, lowered | Describes organ proportions. A flattened stem need not be segmented. |
| prostratus, pendulus | Prostrate, hanging | Two distinct growth directions. They should not be treated as synonyms. |
Stem, branches and segments
| Element or term | Meaning | Examples and explanation |
|---|---|---|
| caulis, kaulos | Stem | Latin caulis and Greek kaulos denote the shoot axis. fusicaulis refers to a spindle-shaped stem. |
| truncus | Trunk | The correct Latin term for a trunk. The former assignment of “trunk” to stemma was incorrect. |
| ramus | Branch | ramosus means branched, ramosissimus very strongly branched. |
| brachium | Arm | brachiatus describes arm-like branches. |
| klados | Branch, offshoot | heterocladus refers to differences between branches, glaucocladus to their glaucous colour. |
| frons | Leafy branch or blade, depending on context | latifrons and acutifrons require checking the organ description. The element alone does not demonstrate typical leaves. |
| sarmentum | Long, slender shoot | sarmentaceus is associated with this habit. The archive used the inaccurate spelling sarmentium. |
| articulus, arthron | Segment or joint | articulatus means segmented. Arthrocereus contains a Greek element referring to joints between segments. |
| stemma | Wreath, crown | This Greek element remains in the comparison as a correction. It is not a term for a stem or trunk. |
Spines, bristles and hairs
| Element or term | Meaning | Examples and explanation |
|---|---|---|
| spina, akantha | Spine, sharp structure | tenuispinus, melanacanthus. Etymology does not replace identification of an organ's origin. |
| aculeus | Prickle or sharp outgrowths in older descriptions | aculeatus. In a strict morphological description, a prickle is a surface outgrowth, while a cactus spine has leaf origin. |
| ankistron, hamus, uncus | Hook | ancistrophorus, multihamatus, uncinatus indicate a hooked curvature. |
| centrum | Centre | centrispinus refers to central spines. Position in the areole is distinct from spine length. |
| acutus, acumen | Sharp, sharply pointed tip | acuminatus indicates a gradually elongated point. The imprecise archival spelling aculius was omitted. |
| cuspis | Point, sharp ending | tricuspidatus means three-pointed. The number refers to a particular feature in the description. |
| subula | Awl | subulatus describes an awl-shaped form tapering to a sharp end. |
| acus | Needle | acifer, acispinosus refer to a needle-like form. |
| arma | Armament | Armatocereus, albiarmatus. A metaphor for defensive traits. |
| acinaces | Short curved sword | acinaciformis, acinacispinus describe a shape resembling a blade. |
| machaira | Blade, knife or sword | Machaerocereus and machaeratus illustrate historical use of the element, not a statement of current genus status. |
| pugio | Dagger | pugionacanthus, pugionifer refer to the shape or presence of dagger-like structures. |
| aor, ensis, gladius, xiphos | Sword | ensiformis, gladiispinus, xiphacanthus. These are different roots evoking similar shapes. |
| hasta, lancea | Spear, lance | hastatus and lanceolatus are not interchangeable. In leaf descriptions they denote different outlines. |
| sarissa | Long spear | sarrisophorus refers to long, sharp armament. |
| chaitē, seta | Bristle | chaetacanthus, saetiger, acanthosetus emphasize a thin, bristly form. |
| pilus, thrix | Hair | Latin pilo- and Greek tricho-. Examples include Pilosocereus and sphaerotrichus. |
| coma, crinis | Tuft, hair | albicomus, brevicrinita. A reference to hair does not establish whether the structure described is a trichome or a thin spine. |
| erion, lana | Wool | eriophorus, laniceps indicate a woolly appearance of a particular part. |
| floccus, cincinnus | Tuft, curl | flocculosus, cincinnatus describe covering arrangement, not a separate cactus organ. |
| pinna, pluma | Feather | pinnatus, plumosus. In cacti, a feathery appearance may result from spine structure. |
| inermis | Unarmed | Closest in meaning to lacking spines or prickles. subinermis means almost unarmed. |
| nudus | Naked, exposed | nudiflorus applies nakedness to the flower. It does not automatically mean the entire plant lacks spines. |
| calvus | Bald, without covering | calvescens indicates becoming bald, losing the covering during development. |
| laevis | Smooth | laevigatus refers to a smooth surface. Smoothness and lack of spines are different traits. |
| glaber | Hairless | glabrescens means becoming hairless. It concerns hairs, not a general statement of spinelessness. |
Shoot surface, leaves, roots and fruits
| Element or term | Meaning | Examples and explanation |
|---|---|---|
| areola | Small area, in cacti an areole | longiareolatus refers to elongated areoles. An areole is the site where a specialized short shoot develops. |
| glochis | Barb, barbed point | glochidiatus refers to glochids. The singular in a Polish description may be rendered as glochidium. |
| derma | Skin | Argyroderma is an example outside Cactaceae. A surface name does not establish the anatomical covering type. |
| sperma, semen | Seed | cardiospermus, dolichospermaticus. The elements may describe shape or other seed traits. |
| fructus, karpos | Fruit | albifructus, platycarpus apply a trait to the fruit. |
| bacca | Berry | baccifer means producing berries. It is not a synonym for every fruit type. |
| pulpa | Pulp | duripulpa refers to pulp hardness. |
| radix, rhiza | Root | brunneiradicatus, macrorhizus, polyrhizus. The term may concern root colour, size or number. |
| rapum, napus | Turnip | napiformis describes resemblance to a turnip, usually organ thickening. It is not a general term for a root. |
| angulus, gonia | Angle | multangularis, hexagonus, heptagonus. An angular cross-section may correspond to ribbing, but “angle” and “rib” are not exact synonyms. |
| costa, pleura | Rib, side | paucicostatus means having few ribs, while pleurocarpus applies ribbing or lateral position to the fruit, depending on the name. |
| mamma, mastos | Breast, projection | grandimamma, Echinomastus refer to tubercles or resemblance in shape. |
| papilla, thēlē | Papilla, tubercle | papillosus, conothele, Thelocactus. Not every microscopic surface papilla is a large shoot tubercle. |
| folium, phyllon | Leaf | grandifolius, rotundifolius, phyllacanthus. The former name Phyllocactus referred to a leaf-like stem, not ordinary leaves. |
The flower and its parts
| Element or term | Meaning | Examples and explanation |
|---|---|---|
| anthos, flos | Flower | micranthus, grandiflorus. The first element is Greek, the second Latin. |
| kalyx, calyx | Calyx | Gymnocalycium refers to a “naked calyx”. The historical meaning does not replace a modern description of the floral tube and pericarpel. |
| sepalum | Sepal | crassisepalus, smaragdisepalus. In many cacti, the boundary between outer and inner tepals is gradual. |
| petalon, petalum | Petal | oxypetalus refers to sharply pointed petals. In a description of a continuous perianth, tepals may be the safer term. |
| stylos, stylus | Style, originally a pillar or stylus | brevistylus, flavistylus describe style length or colour. |
| graphis | Stylus, writing tool | The old brachygraphis illustrates a shape metaphor. graphis should not be used as a universal term for the style. |
| stamen, stēmōn | Stamen | longistamineus refers to stamens. A stamen includes a filament and anther, so it is not the filament alone. |
| filamentum | Thread, including a stamen filament | rubrifilamentosus indicates red filaments. filamenta is plural. |
| anthera, stigma, ovarium | Anther, stigma, ovary | Three supplementary anatomical terms. The anther produces pollen, the stigma receives it, and the ovary contains ovules. |
Former names in the supplied books
Older names remain necessary for finding a description and establishing the author's taxon concept. In modern text, we use the accepted name and give the former one as a synonym. The table covers specific equivalents checked in POWO. Genus names and similar appearance are insufficient to transfer whole descriptions between species. [2-WWW] [2-WWW]
| Former name | Accepted name | Relationship and significance |
|---|---|---|
| Zygocactus truncatus | Schlumbergera truncata | Changed generic combination. We retain the former name when discussing the book. [2-WWW] |
| Chamaecereus silvestrii | Echinopsis chamaecereus | The accepted name follows current POWO. The older combination helps find the earlier description. [2-WWW] |
| Mammillaria wildii | Mammillaria crinita subsp. wildii | It has subspecies rank in the adopted treatment. [2-WWW] |
| Hylocereus undatus | Selenicereus undatus | Transfer to another genus does not mean a different species cultivated as a rootstock. [2-WWW] |
| Dolichothele longimamma | Mammillaria longimamma | A former genus found in literature describing elongated tubercles. [2-WWW] |
| Neomammillaria gaumeri | Mammillaria heyderi subsp. gaumeri | The name from Britton and Rose's monograph now corresponds to a subspecies in POWO's treatment. [2-WWW] |
For monstrous forms, a trade designation and illustration alone may not resolve species identification. Establish the material's provenance and identity first, then update its name. The terms cristata and monstruosa are discussed separately in the chapter on unusual growth. [Mauseth 2006] [Hinz and Abramowicz 1986, pp. 28–32]
The archival text Zasady współczesnego nazewnictwa botanicznego kaktusów was used as a starting point for explaining binomial names and etymology. The rules were updated according to the 2025 Madrid Code. Accepted atlas names were checked in POWO on 8 October 2026. Five tables from the old site were transcribed and reorganized using the supplied images. Incorrect equations of stemma with a trunk, glaber with spinelessness, and the entire stamen with its filament were corrected using P. M. Eckel's dictionary.
Zasady współczesnego nazewnictwa botanicznego kaktusów
[Autor nieustalony, Zasady współczesnego nazewnictwa botanicznego kaktusów, b.d.ad]
An account of botanical nomenclature from Konrad Szychowski's private archive. It contains principles and examples of cactus name etymology. Authorship and date remain undetermined.
Phylogenomics and classification of Cactaceae based on hundreds of nuclear genes
de Vos J. M., Eggli U., Nyffeler R., Larridon I., McGinnie C., Epitawalage N., Maurin O., Forest F., Baker W. J., Phylogenomics and classification of Cactaceae based on hundreds of nuclear genes, Plant Systematics and Evolution, 2025, 311(5):28, doi: 10.1007/s00606-025-01948-z
The study analyses hundreds of nuclear genes and their agreement in reconstructing Cactaceae relationships. It presents a revised classification of subfamilies, tribes and genera with morphological descriptions.
Cactaceae at Caryophyllales.org – a dynamic online species-level taxonomic backbone for the family
Korotkova N., Aquino D., Arias S., Eggli U., Franck A., Gómez-Hinostrosa C., Guerrero P. C., Hernández H. M., Kohlbecker A., Köhler M., Luther K., Majure L. C., Müller A., Metzing D., Nyffeler R., Sánchez D., Schlumpberger B., Berendsohn W. G., Cactaceae at Caryophyllales.org – a dynamic online species-level taxonomic backbone for the family, Willdenowia, 2021, 51(2):251-270, doi: 10.3372/wi.51.51208
The publication presents a taxonomic checklist of Cactaceae from 2021. It organises accepted names, synonyms and references to classification sources.
Phylogenetic relationships in Coryphantha and implications on Pelecyphora and Escobaria (Cacteae, Cactoideae, Cactaceae)
Sánchez D., Vázquez-Benítez B., Vázquez-Sánchez M., Aquino D., Arias S., Phylogenetic relationships in Coryphantha and implications on Pelecyphora and Escobaria (Cacteae, Cactoideae, Cactaceae), PhytoKeys, 2022, 188:115-165, doi: 10.3897/phytokeys.188.75739
A study of five plastid DNA regions, sequence length changes and eight morphological features. It analyses Coryphantha boundaries and relationships between Escobaria species and the two classical Pelecyphora species. It proposes expanding Pelecyphora and publishes new combinations with type and synonym documentation. It discusses tubercle grooves, tepal margins and seed coat sculpturing, including exceptions in P. chihuahuensis and P. macromeris.
Plants of the World Online — Royal Botanic Gardens, Kew
Accepted names, synonyms and distribution. A citation beside a taxon leads to its record.
Accessed 2026-10-08.
International Code of Nomenclature for algae, fungi, and plants (Madrid Code)
[Turland N. J., Wiersema J. H., Barrie F. R., Gandhi K. N., Gravendyck J., Greuter W., Hawksworth D. L., Herendeen P. S., Klopper R. R., Knapp S., Kusber W. H., Li D. Z., May T. W., Monro A. M., Prado J., Price M. J., Smith G. F., Zamora Señoret J. C. (red.), International Code of Nomenclature for algae, fungi, and plants (Madrid Code), Regnum Vegetabile, University of Chicago Press, Chicago, 2025, tom 162]
Current international rules for scientific plant names. The edition published on 21 July 2025 replaced the Shenzhen Code. The full editorial committee is listed in the bibliography. The Code establishes nomenclatural rules, rather than one permissible classification of relationships.
Archiwalne zestawienia terminologii oraz schematy fizjologii, sukulentyzmu i rozmnażania
[Autor nieustalony, Archiwalne zestawienia terminologii oraz schematy fizjologii, sukulentyzmu i rozmnażania, b.d.a]
A set of tables and illustrations from Konrad Szychowski's private archive. It covers terminology, physiology, succulence and propagation. One figure refers to W. Nultsch's 1973 account, identifying that drawing's source rather than dating the entire collection.
Missouri Botanical Garden
A grammatical dictionary of botanical Latin by P. M. Eckel.
Accessed 2026-10-08.
Structure–Function Relationships in Highly Modified Shoots of Cactaceae
Mauseth J. D., Structure–Function Relationships in Highly Modified Shoots of Cactaceae, Annals of Botany, 2006, 98(5):901-926, doi: 10.1093/aob/mcl133
The review describes cactus stem structure, areoles, and photosynthetic and storage tissues. It explains connections between anatomy, photosynthesis and water storage.
Uprawa kaktusów
[Hinz S., Abramowicz M., Uprawa kaktusów, Wydawnictwo Glob, Szczecin, 1986, s. 28–32, 89–112 (udostępnione fragmenty)]
The guide covers cactus structure, growth forms, propagation, cultivation conditions and plant protection. Supplied excerpts describe crested and monstrose forms, winter hardiness, and identification of damage and diseases, among other subjects. Plant protection recommendations document practice at the time of publication.
Kaktusy
[Fleischer Z., Schütz B., Kaktusy, Państwowe Wydawnictwo Rolnicze i Leśne, Warszawa, 1978, wyd. I, trans. Kabiesz Z., Prajer Z.]
Państwowe Wydawnictwo Rolnicze i Leśne, Warsaw, first edition. Translated by Zofia Kabiesz and Zbigniew Prajer. Historical and cultivation background. Names and interpretations updated separately.
Scanning electron microscope studies of the spines and glochids of the Opuntioideae (Cactaceae)
Robinson H., Scanning electron microscope studies of the spines and glochids of the Opuntioideae (Cactaceae), American Journal of Botany, 1974, 61(3):278-283, doi: 10.1002/j.1537-2197.1974.tb10775.x
The paper presents glochid microscopic structure. It compares shaft surfaces, barbs and bases and discusses their significance in the systematics of the time.
Root Structure and Function
[Dubrovsky J. G., North G. B., Root Structure and Function, Cacti: Biology and Uses, University of California Press, Berkeley i Los Angeles, Nobel P. S. (red.), 2002, s. 41–56]
The chapter presents cactus root structure and function. It discusses anatomy, water uptake and hydraulic conductivity under changing hydration conditions.
Blurring the Boundaries between a Branch and a Flower — Potential Developmental Venues in Cactaceae
Rosas-Reinhold I., Piñeyro-Nelson A., Rosas U., Arias S., Blurring the Boundaries between a Branch and a Flower — Potential Developmental Venues in Cactaceae, Plants, 2021, 10(6):1134, doi: 10.3390/plants10061134
The account analyses the origin and development of cactus floral structures. It discusses the pericarpel and different interpretations of stem tissue contributions to flower organisation.
