A herbarium is a curated collection of preserved plant specimens, each mounted, labelled, and organised so it can be studied for generations. Far more than a cabinet of dried leaves, a herbarium is one of science’s oldest and most enduring instruments – a permanent record of which plants grew where, when, and alongside what knowledge. This guide explains what a herbarium is, how herbaria began, the different types that exist, and why these quiet archives matter more now than ever.

In short
A herbarium is a permanent, scientifically organised collection of pressed and dried plant specimens, mounted on archival sheets together with data on where and when each was gathered. Herbaria serve as reference libraries of plant life, supporting research in taxonomy, ecology, conservation, and the study of how cultures use plants.

What Is a Herbarium, Exactly?

At its simplest, a herbarium is a library – but its volumes are plants. Each specimen is typically pressed flat, carefully dried, and affixed to a sheet of acid-free paper. Beside it sits a label recording the species, the place and date of collection, the habitat, the name of the collector, and often notes on how local people knew and used the plant. That pairing – a physical specimen plus its data – is what turns a dried plant into a piece of evidence.

A specimen may be a whole plant or only the parts needed to identify it: a flowering branch, a fruit, a root, a fragment of bark. Held in stable conditions, these specimens last for centuries. As Dr. Barbara Thiers, Director Emerita of the New York Botanical Garden, puts it on the Academy’s Brainforest Café podcast, a herbarium is the botanical equivalent of a museum – the difference being that its purpose is to document the full range of plant biodiversity. The result is a botanical archive that any researcher, anywhere, can return to and re-examine, long after the meadow, forest, or wetland where the plant once grew has changed or vanished. This is what makes a herbarium foundational to ethnobotany and plant medicine.

A Brief History of Herbaria: From Luca Ghini to Linnaeus

The herbarium is an invention of Renaissance Europe, and it has endured for roughly five centuries. The practice is credited to Luca Ghini, a sixteenth-century Italian botanist who pioneered the idea of pressing and drying plants so they could be kept, compared, and consulted long after the growing season ended. Tellingly, his original aim was medicinal: Ghini wanted his students to study the healing properties of real plants rather than relying solely on the classical texts of Dioscorides. It was a quiet revolution: the study of plants moved from the pages of ancient texts onto the evidence of the living earth.

The oldest surviving herbarium is generally attributed to Ghini’s contemporary Gherardo Cibo. Two centuries later, Carl Linnaeus – architect of the system we still use to name species – advocated mounting each specimen on its own loose sheet rather than binding them into books, so collections could be endlessly reordered as understanding grew. That simple decision shaped how herbaria are organised to this day.

A Diversity of Collections: The Types of Herbaria

A herbarium is far from a museum of the past; it is a working scientific tool. Its uses reach across disciplines:

• Taxonomy and identification. When a species is first described, a single specimen – the “type” – is preserved as the permanent reference against which all later identifications are checked.
• Biodiversity and conservation. Specimens document which species existed in a place and time, helping track range shifts, rediscover plants thought lost, and prioritise what to protect.
• Climate and ecology. Dated collections reveal how flowering times, distributions, and ecosystems have changed over decades and centuries.
• Chemistry and medicine. Specimens can be sampled for DNA and compounds, linking plant identity to the healing properties people have relied on for generations.
• Cultural memory. Collection labels often carry Indigenous and local names and uses – a written trace of living plant knowledge.

This breadth is why the work of great plant collectors endures. The specimens gathered by figures such as Richard Evans Schultes in the Amazon still inform research today, decades after they were pressed.

Types of Herbaria

The word “herbarium” covers more than collections of flowering plants. The main types of herbaria specialise in different branches of life, and many large institutions hold several under one roof:

Many herbaria also preserve algae, mosses and other bryophytes, and lichens, so the term effectively spans much of the green and fungal world. Whichever of these types of herbarium a collection belongs to, its purpose is the same: to document plant and fungal life in a form that lasts.

Herbaria, Indigenous Knowledge, and the BioGnosis Project

For the McKenna Academy, a herbarium is not only a scientific resource but a vessel of cultural memory. The Academy’s BioGnosis project focuses on a single, extraordinary collection: the Herbario Amazonense at the Universidad Nacional de la Amazonía Peruana (UNAP) in Iquitos, Peru – the Herbarium of the Amazon.

Within its walls lie some 150,000 biological specimens – though only around a third have so far been mounted, cataloged, and entered into the collection. These are not ordinary plants but living records of Indigenous knowledge: documentation of how the plants of the Amazon are used for healing. Working with the herbarium’s longtime curator, Juan Ruiz – a bridge between scientific botany and traditional medicine – BioGnosis aims to unpack, preserve, and digitise this archive so that both the specimens and the wisdom they carry endure. The project draws guidance from Dr. Barbara Thiers, who joined as an advisor after discussing the herbarium’s future with Dennis McKenna on the Brainforest Café. It is a model of reciprocity rather than extraction, and part of a wider effort to honour the way Indigenous cultures understand healing plants – from the Amazon to southern Africa.

The Future of Herbaria: Digitization and Beyond

The digital age is opening these centuries-old collections to the world. As specimens are photographed and their label data transcribed, a sheet held in one city becomes searchable from anywhere – widening access for education, collaboration, and research, and helping to weave scientific records together with living Indigenous wisdom. New tools, including the application of large language models to ethnobotany, are beginning to surface patterns across millions of records.

The challenges are real: herbaria need sustained funding and expertise, and the collecting itself raises ethical questions about consent and benefit-sharing with the communities whose knowledge is recorded. Meanwhile, habitat and species loss only deepen the urgency of documenting plant life while it is still here. In that light, a herbarium stands as both a record and a quiet form of hope – a commitment to keep what we have learned, and to keep learning from it.

Frequently Asked Questions About Herbaria

What is a herbarium?

A herbarium is a permanent, scientifically organised collection of preserved plant specimens. Each plant is usually pressed, dried, and mounted on an archival sheet alongside a label recording its species, location, collection date, habitat, and collector. Herbaria function as reference libraries of plant life, allowing researchers to study, compare, and re-examine specimens for decades or even centuries after they were gathered.

What is a herbarium used for?

Herbaria are used to identify and name species, document biodiversity, guide conservation, and track ecological change over time. Researchers consult them to confirm a plant’s identity against an original reference specimen, study how distributions and flowering times have shifted, sample specimens for DNA or chemical analysis, and trace the cultural uses of plants recorded on collection labels.

Who created the first herbarium?

The herbarium is credited to Luca Ghini, a sixteenth-century Italian botanist who pioneered pressing and drying plants for long-term study. The oldest surviving herbarium is generally attributed to his contemporary Gherardo Cibo. Later, Carl Linnaeus introduced the practice of mounting each specimen on its own loose sheet, allowing collections to be reorganised as scientific understanding grew — a convention still followed today.

What is the difference between a herbarium and a botanical garden?

A botanical garden cultivates living plants; a herbarium preserves dried, mounted specimens for scientific reference. The two are complementary. A garden lets people observe plants growing through their life cycles, while a herbarium provides a permanent, dated record that can be studied indefinitely and compared with specimens collected anywhere in the world. Many institutions maintain both.

What are the different types of herbaria?

Beyond the general herbarium of vascular plants, specialised collections include the fungarium (fungi), the xylarium (wood specimens), and the hortorium (cultivated plants). Many herbaria also preserve algae, bryophytes such as mosses, and lichens. Large institutions frequently house several of these collections together, so the single term “herbarium” can encompass a wide span of plant and fungal life.

How are herbarium specimens preserved?

Most specimens are pressed flat, dried to remove moisture, and mounted onto acid-free paper, then stored in stable, pest-controlled conditions. Each sheet carries a label with the species name and collection data. Kept this way, specimens remain intact for centuries. Increasingly, collections are also digitised — photographed and transcribed — so their information can be shared and searched online.

Why are herbaria important today?

Herbaria are essential tools for understanding and protecting biodiversity. They document which species exist and where, supply the reference points that taxonomy depends on, and reveal how plants and ecosystems are responding to a changing climate. As habitat and species loss accelerate, these dated, verifiable records become ever more valuable for research, conservation, and the preservation of cultural plant knowledge.

What is the Herbarium of the Amazon and the BioGnosis project?

The Herbarium of the Amazon is the Herbario Amazonense at the Universidad Nacional de la Amazonía Peruana (UNAP) in Iquitos, Peru, holding around 150,000 specimens. Through its BioGnosis project, the McKenna Academy is helping digitise and safeguard this collection alongside curator Juan Ruiz, preserving both the specimens and the Indigenous healing knowledge they document for future generations.

Further reading & listening: For a rich, accessible history of these collections, see Barbara M. Thiers, Herbarium: The Quest to Preserve and Classify the World’s Plants (Timber Press, 2020). Dr. Thiers – Director Emerita at the New York Botanical Garden and editor of Index Herbariorum — also joins Dennis McKenna on the Academy’s Brainforest Café podcast to discuss the role of herbaria in protecting biodiversity and Indigenous knowledge.