One pepper usually carries four identifiers at once: a Latin binomial, a genebank accession number, a set of descriptor codes, and whatever the seller calls it. Each answers a different question and none replaces the others. The scale of the problem shows in the genotyping. Tripodi and colleagues sequenced 10,038 Capsicum accessions from five genebanks in 2021 and found 1,618 of them were genetic duplicates of something already in the set.

Binomial names, and the gap they leave

The International Code of Nomenclature for algae, fungi, and plants governs the Latin name: genus, species, and an infraspecific rank where one applies, as in Capsicum baccatum var. pendulum. Herbaria, floras and taxonomic papers run on it. It has nothing to say about cultivars. Ghost Pepper, Bhut Jolokia and Naga Jolokia all sit inside Capsicum chinense, and the botanical code takes no position on whether those three names point at one pepper or three. Cultivated plants fall under a separate code, the ICNCP, which almost no chile line actually follows.

Genebank accession numbers

An accession number points at one seed lot in one institution, with passport data attached: collection site, collection date, collector, taxonomy as determined by that genebank. This is the identifier a paper cites when the authors want someone else to repeat the work. Prefixes matter, because several look alike and belong to different institutions.

InstitutionPrefixCapsicum holdingsNote
USDA National Plant Germplasm SystemPI, GRIFNot published as one figureOpen catalogue through GRIN-Global; ships seed for research.
World Vegetable Center, TaiwanVI8,165 accessionsLargest Capsicum collection at any single institution, about 11 percent of world holdings.
IPK Gatersleben, GermanyCAP1,241 C. annuum accessionsThe CAP numbers growers trade come from here, not from New Mexico.
CGN, WageningenCGNAbout 1,200 accessionsFourth largest collection in Europe; detailed passport data.
NMSU Chile Pepper InstituteNMCANot publishedCited as NMCA in the NMSU literature; sells seed to the public separately.
Embrapa, BrazilBGH, CNPHNot published as one figureThe reference collection for wild and Amazonian material.

WikiPepper carries hundreds of these numbers as entries in their own right, including CAP 0213, a C. baccatum at 8,000 to 25,000 SHU. Genesys, the global portal at genesys-pgr.org, pulls accession records from most of these institutions into one search.

What is a Capsicum descriptor list?

A descriptor list is a controlled vocabulary for recording traits, so that two genebanks mean the same thing by "flower position" or "fruit shape at pedicel attachment". The standard for peppers is Descriptors for Capsicum, published in 1995 by IPGRI, AVRDC and CATIE. It is not a curiosity. Bosland and Baral used it to characterize Bhut Jolokia for their 2007 species determination. Without a shared descriptor set, one genebank's "conical" and another's "elongate" cannot be compared at all.

Genomic classification

Marker work has overtaken morphology for sorting close relatives. The Horizon 2020 project G2P-SOL ran from 2016 to 2021 across 19 full partners and 20 associated partners, covering pepper, tomato, eggplant and potato. It genotyped 10,301 pepper accessions by genotyping-by-sequencing, then cut a 400-accession C. annuum core collection for dense genotyping and field phenotyping. The earlier EU-SOL project, which older articles often cite here, worked on tomato and potato, not pepper.

Why do records for the same pepper disagree?

Because the systems measure different things, and because heat moves. Guinness recognized Red Savina at 577,000 SHU, but when Bosland and Baral grew it at Las Cruces in 2005 it tested 248,556 SHU in the same trial where Bhut Jolokia reached 1,001,304. Neither number is wrong. One is a record set under ideal conditions, the other is one field, one season, one lab. Accession records are equally fragile: the 2021 genotyping found that only 63.5 percent of IPK's Capsicum holdings and 80.4 percent of the Universitat Politècnica de València's were unique within their own collection.

The Universal Pepper Number

WikiPepper issues a Universal Pepper Number for the varieties, hybrids and selections that will never see a formal accession number. A code runs S-C-P-F-T-###: species, ripe color, pattern and skin, pod form, heat digit, serial. The heat digit comes off the top of the SHU range on the 0 to 9 Perceived Heat Scale, so a pepper rated 2,500 to 8,000 SHU reads 4 and not 3. The WikiPepper Foundation issues every code from one ledger, and a serial never gets handed out twice, even after a code retires. Nothing here competes with GRIN or IPK. It fills the space below them.

Which system should a grower actually use?

Start with the binomial, because species drives pollination, germination and cross compatibility. Use an accession number when you want the same seed lot twice, and quote it in full with its prefix. Use a descriptor term when you write up a trait so other people can read it. Use a UPN when you need one handle for a pepper that trades under six names. The glossary defines the recurring terms, and three sibling pieces go deeper: classification systems in detail, the taxonomy guide, and species, landraces and cultivars.

Sources & Further Reading