Tropicos: Botanical Nomenclature and Data Guide

In botanical systematics and biodiversity informatics, taxonomic workflows require unambiguous plant names tied to original literature and physical specimen vouchers. Tropicos is the botanical database and nomenclatural repository established and curated by the Missouri Botanical Garden (MBG). For plant scientists, herbarium curators, and data managers, Tropicos connects botanical nomenclature, typification data, bibliographic protologues, and digitized specimen records across global vascular plants and bryophytes.

This guide explains the architecture of Tropicos, how researchers query names and physical vouchers through its primary search modules, how to access data programmatically using the Tropicos Web Services REST API, and how Tropicos compares with complementary botanical platforms such as the International Plant Names Index (IPNI) and Plants of the World Online (POWO).

What It Is

Tropicos is an open-access taxonomic and nomenclatural database developed to computerize the botanical holdings and research of the Missouri Botanical Garden in St. Louis, Missouri. Originated from the VAST (VAScular Tropicos) system in the early 1980s, the platform has expanded over four decades into an international botanical repository.

Tropicos integrates four interconnected record classes within a single relational database:

• Nomenclatural Records: Scientific names of vascular plants and bryophytes, including taxonomic rank, author citation, basionym, nomenclatural status, homotypic and heterotypic synonyms, and the bibliographic protologue citation where the name was published.
• Specimen Voucher Records: Collection metadata for physical herbarium specimens, linking collector names, collector numbers, gathering dates, localities, coordinates, phenological notes, and determination histories.
• Digital Images: High-resolution photographs of living plants and digital scans of mounted herbarium sheets, with emphasis on nomenclatural type specimens (such as holotypes and isotypes).
• Bibliographic References: A catalog of botanical literature, periodicals, monographs, and floristic treatments directly linked to the plant names and specimens cited within them.

By connecting nomenclatural concepts directly to physical vouchers and published literature, Tropicos provides verifiable data provenance that allows botanists to trace the empirical foundation behind historical and current taxonomic determinations.

Who Runs It and What It Covers

Tropicos is owned, hosted, and curated by the Missouri Botanical Garden in St. Louis, Missouri. A team of professional plant taxonomists, nomenclatural specialists, and herbarium staff continually curate and update the database.

The taxonomic scope of Tropicos encompasses two major embryophyte divisions:

• Vascular Plants (Tracheophytes): Angiosperms (flowering plants), gymnosperms, and seedless vascular plants (ferns and lycophytes).
• Bryophytes: Mosses (Bryophyta), liverworts (Marchantiophyta), and hornworts (Anthocerotophyta), reflecting MBG’s research collections in bryology.

Tropicos does not cover algae or fungi, which are indexed in separate repositories such as AlgaeBase and Index Fungorum.

Geographically, Tropicos is global in scope but holds exceptional historical depth in the Americas and the Neotropics. MBG field research across Central and South America, Madagascar, and temperate Asia has populated the database with extensive specimen records and regional floristic treatments, including Flora Mesoamericana, the Catalogue of the Vascular Plants of the Americas, and the Flora of China.

Indexed in the Registry of Research Data Repositories (re3data.org), Tropicos operates as an open-access repository adhering to FAIR data principles. It provides Darwin Core Archive data feeds to international aggregators, including the Global Biodiversity Information Facility (GBIF), supporting large-scale biodiversity mapping and conservation research.

How to Search and Use Tropicos

Researchers access Tropicos via tropicos.org or programmatically through its RESTful Web Services API. The platform provides specialized modules for distinct taxonomic tasks. Authorized contributors sign in via the upper utility navigation, while general searching is open without registration.

1. Search by Name: Open the Name Search module to query scientific binomials, genera, or infraspecific epithets. Filter results by family, taxonomic rank, or author citation.
2. Inspect Nomenclatural Cards: Select a Name record to view its author citation, protologue reference, basionym details, homotypic/heterotypic synonyms, and published chromosome counts.
3. Search Specimen Vouchers: Use the Specimen Search module to locate physical herbarium vouchers by collector name, collector number, year, country, or province. Records show verbatim locality data, determination histories, and digitized specimen images.
4. Query Floristic Projects: Use Project Search to restrict queries to regional checklists (such as regional floras and protected area inventories) to view floristic treatments applicable to specific geographic regions.
5. Access Programmatically via REST API: Register for an API key at http://services.tropicos.org/. Query endpoints using HTTP GET requests with authentication (apikey=YOUR_KEY) and response format (format=json or format=xml). Standard endpoints include /Name/{id} for taxon metadata, /Name/Search for string queries, and /Name/{id}/Synonyms for synonymy lists.
6. Export and Cite Records: Capture permanent record URLs and unique Tropicos Name IDs or Specimen IDs for inclusion in publications following guidelines for citing research datasets.

Strengths and Limits

Strengths

• Specimen-Grounded Taxonomy: Integrates published nomenclature with physical herbarium vouchers and digitized type specimens, enabling direct verification of anatomical characters.
• Neotropical and Flora Coverage: Contains unparalleled taxonomic depth for Central and South American plants, backed by decades of MBG field research and monograph series.
• Public REST API: Provides structured endpoints for automated name reconciliation and integration into tools such as R’s taxize package.
• Historical Determination Tracking: Preserves successive specimen determinations over time, maintaining historical attribution and taxonomic audit trails.

Limits

• Taxonomic Scope Boundaries: Covers only vascular plants and bryophytes; fungi, algae, and lichens must be investigated through specialized external databases.
• Multiple Project Classifications: Because Tropicos hosts diverse regional floristic projects, a single taxon name may reflect differing synonymy or acceptance statuses depending on the project checklist consulted.
• Historical Data Heterogeneity: Older specimen records entered in early VAST project phases may lack geographic coordinates or high-resolution imagery compared to contemporary accessions.

Alternatives: Tropicos vs IPNI and POWO

Plant scientists routinely consult multiple botanical repositories. Understanding the distinct roles of Tropicos, IPNI, POWO, and GBIF clarifies which resource best addresses specific research needs.

Feature	Tropicos	IPNI	Plants of the World Online (POWO)	GBIF
Host Institution	Missouri Botanical Garden	RBG Kew, Harvard Herbaria, Australian National Herbarium	Royal Botanic Gardens, Kew	GBIF Secretariat
Core Focus	Nomenclature, herbarium specimen vouchers, and floras	Nomenclatural registry of published vascular plant names	Global taxonomic consensus backbone (WCVP)	Global biodiversity occurrence and specimen aggregator
Taxonomic Status Opinions	Project-specific accepted names and curated synonymies	None (strictly nomenclatural; no accepted vs synonym judgments)	Explicit consensus judgments (accepted, synonym, unplaced)	Aggregates taxonomic trees across multiple backbones
Specimen Vouchers	Physical herbarium records with scans, barcodes, and locality data	Records nomenclatural types from literature only	Selected type images and representative specimen links	Physical specimen and observation records globally
Taxonomic Scope	Vascular plants and bryophytes	Vascular plants	Vascular plants	All living taxa (plants, animals, fungi, bacteria)
API Architecture	REST API (JSON/XML) with API key parameter	REST API and downloadable archives	REST API	REST API and Darwin Core Archive downloads

In standard practice, researchers consult IPNI to verify publication details and author citations without subjective taxonomic filtering. POWO provides consensus accepted names and baseline distributions. Tropicos is essential for examining underlying herbarium vouchers, verifying Neotropical floras, reviewing type specimen imagery, and evaluating regional floristic treatments curated by MBG.

Frequently Asked Questions

What is the difference between Tropicos and IPNI?

IPNI (International Plant Names Index) is purely a nomenclatural index recording when and where vascular plant names were validly published, with author citations and type literature, without judging whether a name is accepted or a synonym. Tropicos combines nomenclatural indexing with taxonomic curation, linking names to physical herbarium vouchers, digitized specimens, synonyms, and regional floristic projects.

Does Tropicos indicate whether a plant name is accepted or a synonym?

Yes. Tropicos displays homotypic and heterotypic synonyms for taxon names. Because Tropicos maintains multiple regional floras and checklists, a name’s accepted status may be contextualized within a specific project treatment (such as Flora Mesoamericana) rather than enforced as a single rigid global consensus.

How should researchers cite data from Tropicos?

Publications should cite the Missouri Botanical Garden and provide the URL: Tropicos.org. Missouri Botanical Garden. Available at: https://www.tropicos.org (2026). When referencing a specific taxon or voucher, include the unique Tropicos Name ID or Specimen ID and direct URI to maintain machine-actionable persistent identifiers.

Is an API key required to use Tropicos Web Services?

Yes. Automated queries to the REST API at http://services.tropicos.org/ require an API key requested via the Tropicos help portal and passed via the apikey query parameter. Manual browsing via tropicos.org requires no account.

Does Tropicos cover non-vascular plants, fungi, or algae?

Tropicos covers vascular plants and bryophytes (mosses, liverworts, and hornworts). It does not index algae, lichens, fungi, or animal taxa, which are cataloged in specialized registries such as Index Fungorum, MycoBank, or AlgaeBase.

Sources

• Missouri Botanical Garden. Tropicos Database Portal. Available at: https://www.tropicos.org.
• Missouri Botanical Garden. Tropicos Web Services API Documentation. Available at: http://services.tropicos.org/.
• Registry of Research Data Repositories (re3data.org). Tropicos Repository Record (r3d100010464). Available at: https://www.re3data.org/repository/r3d100010464.
• Royal Botanic Gardens Kew, Harvard University Herbaria, and Australian National Herbarium. International Plant Names Index (IPNI). Available at: https://www.ipni.org.
• Royal Botanic Gardens Kew. Plants of the World Online (POWO). Available at: https://powo.science.kew.org.