The abbreviation “spp.” in a plant name stands for “species pluralis,” meaning multiple species within the same genus. When you see something like Carpobrotus spp. on a plant label, in a research paper, or on a government weed-management list, the writer is referring to several (or all) species in the genus Carpobrotus without singling out any one of them. It is a small piece of taxonomic shorthand, but it shows up constantly in gardening guides, agricultural bulletins, and ecological studies, and understanding it unlocks how scientists talk about plants when exact identification is uncertain, unnecessary, or still in progress.
How “spp.” Differs from “sp.”
The distinction is purely about number. When a writer means one unidentified species within a genus, the correct abbreviation is “sp.” (singular). When the reference is to two or more species in the same genus, the abbreviation becomes “spp.” (plural). A field ecologist who collects a single grass specimen she cannot identify to the species level might record it as Poa sp. If she is writing about all the bluegrasses in a meadow without listing each one, she would write Poa spp.1BioScience Writers. Species Taxonomy Nomenclature
Neither abbreviation is italicized, even though the genus name before it is. That is because the genus is a formal Latin name governed by the International Code of Nomenclature for algae, fungi, and plants, while “sp.” and “spp.” are just shorthand notes. You will sometimes see them wrongly italicized in popular writing, but in scientific style they stay in roman type.
Why Scientists Choose “spp.” Instead of Listing Every Species
There are several practical reasons a botanist or plant pathologist might reach for “spp.” rather than spelling out each species name. The most common is simple convenience. A genus can contain dozens or even hundreds of species, and when the point being made applies to the group rather than to any single member, listing them all would bury the reader. A plant pathologist writing about rust diseases of cereal crops, for instance, can say Puccinia spp. and cover the whole sweep of wheat rust, oat crown rust, and barley leaf rust in two words. In a survey of the international plant-pathology community that ranked the most scientifically and economically important fungal pathogens, Puccinia spp. ranked third and Colletotrichum spp. ranked eighth, with neither entry narrowed to a single species because the damage comes from multiple members of each genus.2PubMed Central. The Top 10 fungal pathogens in molecular plant pathology
A second reason is genuine uncertainty. Field identification of plants can be difficult, especially when specimens are sterile (lacking flowers or fruit) or when the distinguishing features between closely related species are subtle. Historical ecological surveys provide a good example: witness-tree records from early land surveys often contain trees that were misidentified or recorded under names that cannot be matched to any known species.3Wiley Online Library. Influences of Native Americans and Surveyor Biases on Metes and Bounds Witness-Tree Distribution When researchers work with that kind of ambiguous data, “spp.” is the honest label. It says “we know the genus but not which species.”
A third reason is that taxonomy itself is unsettled. Plant genera are regularly revised as new genetic evidence reshuffles the boundaries between species. A group of plants that was considered a single species last year may be split into three this year, or vice versa. Using “spp.” lets a writer sidestep a taxonomic argument that is irrelevant to the point being made.
Where You Will See “spp.” in Everyday Contexts
You do not need to be a taxonomist to run into this abbreviation. It appears on nursery labels (especially for genera sold under multiple species, like Salvia spp. or Eucalyptus spp.), in pest and disease alerts from agricultural extension services, on invasive-species watchlists, and in ingredient lists for herbal products. If a supplement bottle lists Echinacea spp., that means the manufacturer sourced from more than one species of coneflower, or is not specifying which one.
In invasive-species management, the abbreviation is especially common because control programs often target an entire genus rather than a single species. Research on invasive ice plants in coastal habitats, for example, refers to Carpobrotus spp. because more than one species from that South African genus has spread into Mediterranean and Atlantic coastlines, depleting and replacing native plant communities.4Biological Invasions. (Not) sweeping invasive alien plants under the carpet: results from the use of mulching sheets for the control of invasive Carpobrotus spp. A land manager pulling ice plants does not need to pause and determine whether a particular mat is Carpobrotus edulis or Carpobrotus acinaciformis; both are targets, and “spp.” covers the job.
Related Abbreviations You Might Confuse with “spp.”
Plant names come with a small family of similar-looking abbreviations, and mixing them up is easy. Here are the ones that cause the most confusion:
- sp.: One unspecified species in a genus (Quercus sp. = one unknown oak).
- spp.: Multiple or all species in a genus (Quercus spp. = oaks in general).
- subsp. (or ssp.): A subspecies, a rank below species used when a population is geographically or ecologically distinct but still interbreeds with other populations of the same species.
- var.: A variety, another rank below species, typically describing a naturally occurring morphological variant.
- f. (or forma): The lowest commonly used rank, usually applied to a minor and sporadic variation like flower color that has no geographic or ecological pattern behind it.
Subspecies and varieties are usually defined as having some geographic, ecological, or evolutionary coherence beyond just looking different, while formae are defined as lacking that broader integrity.5TAXON. Current practice in the use of subspecies, variety, and forma in the classification of wild plants In practice the line between subspecies and variety is blurry, and different botanical traditions use them differently. North American botanists lean toward “var.” while European botanists lean toward “subsp.” for what are essentially equivalent situations. None of these ranks, though, should be confused with “spp.,” which operates at a completely different level: it is about grouping across species, not splitting below them.
How DNA Barcoding Is Changing When “spp.” Gets Used
One of the forces reshaping how often scientists resort to “spp.” is the spread of molecular identification. Instead of relying solely on visible features like leaf shape or flower anatomy, researchers can now sequence short stretches of DNA to pin down which species a sample belongs to. Recent work on agricultural crops has identified combinations of three or four chloroplast gene regions that can distinguish plants even at the cultivar level, well below the species threshold.6Europe PMC. DNA-Barcoding for Cultivar Identification and Intraspecific Diversity Analysis of Agricultural Crops
This matters because “spp.” was historically a workaround for situations where visual identification failed. When a plant was too young, too damaged, or too similar to a close relative for anyone to confidently name the species, “spp.” gave the writer a graceful exit. DNA barcoding closes many of those gaps. A dried herbarium sheet that stumped morphologists for decades can now be sequenced and assigned to a species. An ambiguous seedling in a quarantine inspection can be identified from a leaf clipping in a day or two.
That said, barcoding has not made “spp.” obsolete. Molecular techniques sometimes reveal the opposite of clarity: they show that what everyone thought was one species is actually a cluster of cryptic species that look identical but are genetically distinct. In those cases, the number of species in a genus can jump overnight, and researchers who are not yet sure how to sort the new species may fall back on “spp.” more than ever. Barcoding is also expensive and slow compared with writing “spp.” on a field notebook, so the abbreviation remains the practical default for large-scale ecological surveys where thousands of specimens pass through.
When “spp.” Creates Problems in Law and Regulation
The casual convenience of “spp.” runs into trouble when legal consequences hinge on species-level identification. International wildlife trade regulations and endangered-species laws are written around species names. A plant listed as endangered is protected at the species level: Cycas beddomei is protected, but the broader genus Cycas includes species that are perfectly legal to trade. If a customs inspector intercepts a shipment labeled Cycas spp., determining whether the plants are the protected species or a legal relative is the entire enforcement question.
This challenge is well documented in wildlife trade enforcement more broadly. Species-defining characters are often absent from traded items, making identification difficult. When taxonomists split a previously recognized species into new ones, enforcement lags and regulatory loopholes can follow, because the new species names may not yet appear on protected-species lists.7PubMed. The species dilemma and its potential impact on enforcing wildlife trade laws For plants, the same dynamic plays out with timber, traditional medicines, and ornamental species. A shipment of orchid tubers ground into powder and labeled Orchis spp. could contain CITES-listed species or common ones, and there is no way to tell by looking.
Regulatory agencies handle this in different ways. Some list entire genera as protected, making the “spp.” question moot: if the genus is restricted, every species in it is restricted. Others rely on DNA testing of suspect shipments, which brings the barcoding tools described above into the courtroom. The tension between taxonomic convenience and legal precision is ongoing and unlikely to be resolved soon, because taxonomy itself keeps shifting.
Common Misconceptions About “spp.”
A few misunderstandings come up regularly, even among people who work with plants professionally.
The first is that “spp.” means “subspecies.” It does not. Subspecies is abbreviated “subsp.” or sometimes “ssp.” The two abbreviations look similar at a glance, especially in handwritten field notes, but they refer to entirely different levels of classification. “Spp.” points upward from species to the genus level; “subsp.” points downward from species to a finer division.
The second is that “spp.” implies the species are closely related to each other beyond sharing a genus. It does not make that claim. A genus can contain species that diverged millions of years ago and occupy completely different habitats. Eucalyptus spp. includes rainforest trees and desert scrub. The abbreviation groups them by name, not by ecological similarity.
The third is that seeing “spp.” means the writer was lazy or imprecise. Sometimes that is true, but more often the abbreviation is the most accurate thing the writer could say. If a finding genuinely applies to every tested species in a genus, or if the exact species cannot be determined, “spp.” is not vague; it is honest. Forcing a single species name onto an ambiguous specimen is worse science than admitting the ambiguity.
How Plant Names Work Around “spp.”
To make sense of where “spp.” fits, it helps to see the structure it lives inside. Every plant species has a two-part Latin name: the genus (capitalized) and the specific epithet (lowercase). Rosa canina is the dog rose. The genus Rosa contains all roses. When you swap the specific epithet for “spp.,” you are erasing the second half of the name and saying “this genus, multiple species, take your pick.”
Above the genus sit higher ranks like family, order, and class, but those rarely appear in everyday plant references. Below the species sit the subspecies, variety, and forma ranks discussed earlier. The species level is where most practical action happens: it is the unit that gets listed on endangered-species schedules, described in field guides, and sold in nurseries. “Spp.” is essentially a way to hover one step above that practical unit when precision at the species level is not the point.
One subtlety worth noting: “spp.” is used exclusively with the genus name. You would not write a family name followed by “spp.” If a writer wants to refer to multiple genera within a family without listing them, they use the family name alone (Rosaceae, for instance, rather than Rosa spp. + Prunus spp. + Malus spp.). The abbreviation is locked to the genus-species pairing that defines binomial nomenclature.
When a Genus Is Split or Lumped
Taxonomy is not fixed. Genera get reorganized as genetic data accumulate, and those reorganizations ripple through every document that used “spp.” with the old genus name. A classic example in the plant world is the ongoing reshuffling of Aster. What North American gardeners still call asters were largely moved out of Aster and into Symphyotrichum, Eurybia, and other genera starting in the 1990s. An older paper referring to Aster spp. in North American prairies means something different from a modern paper using the same phrase, because the genus Aster is now understood to be mostly Eurasian.
This kind of revision means that “spp.” does not point to a stable, permanent set of species. It points to whatever species are currently classified in that genus according to the taxonomic authority being followed. Two papers published five years apart may use the same “spp.” label and mean different collections of organisms. For a casual reader, this rarely matters. For someone trying to compare data across studies or comply with a regulation, it can be a genuine headache. The safest approach, when precision matters, is to check which taxonomic reference the author was using and verify which species fell under that genus at the time of writing.