Heirloom, landrace and traditional vegetables: the science and the societies
What it means to pass on a seed — from the science of genetic diversity to the systems that safeguard heirloom vegetables in Japan and worldwide
2026-06-23 · 26 min read
Most vegetables on supermarket shelves are F1 hybrids, whose seed must be bought anew from seed companies each year. Alongside them are open-pollinated heirlooms, landraces and traditional vegetables — kept alive by generations of farmers who saved their own seed and selected it, year after year, for their own land. These are not merely nostalgic vegetables but living genetic resources, shaped over long stretches of time by local climate, food culture and human hands. Drawing on some fifty studies, this column moves from first principles — the difference between an open-pollinated variety and an F1 hybrid — through the science of genetic erosion, the research on flavor and nutrition, the conservation machinery of genebanks and seed sovereignty, the traditional vegetables of Japan such as Kyo-yasai and Edo-Tokyo vegetables, and finally the gardens around the world where cities themselves have become places that keep heirloom seeds alive.
Opening
In an age of buying seed, the choice to pass it on
Even people who have grown vegetables often hesitate when asked, 'Could you save the seed of this vegetable for next year?' Many modern vegetables are F1 hybrids: excellent for yield and uniformity, but their saved seed does not breed true to the parent. So growers buy fresh seed from seed companies every year. Open-pollinated heirlooms and landraces, by contrast, grow true from saved seed, so the farmers themselves can carry the seed forward across generations.
This difference is not only about taste or ease of growing. Heirlooms and landraces carry genetic variation within the population, and that variation is the wellspring of their adaptability to disease and a changing climate. The world's food supply is leaning ever harder on just a handful of crops (Khoury et al., 2014, PNAS), and the quiet disappearance of local varieties — 'genetic erosion' — thins out the future of food itself. To pass on a seed is to keep options open for the future.
Clarifying terms
Heirloom, landrace, traditional vegetable — how do they differ?
First, the vocabulary. A 'fixed' or open-pollinated variety breeds true: its traits remain stable as seed is saved and resown. A 'landrace' is a dynamic population that has adapted to a place over long cultivation — genetically diverse yet coherent as a whole (Camacho Villa et al., 2005). A 'traditional vegetable' is such a landrace whose name has become bound up with the food culture and history of a region. The English word 'heirloom' broadly denotes an open-pollinated variety handed down across generations.
These concepts overlap, and the exact lines depend on context. What matters is the contrast with the F1 hybrid: the first-generation cross of two distinct parents, uniform and high-yielding, but whose second generation (F2) segregates and loses that uniformity. It is precisely the heirloom's and landrace's capacity to 'save your own seed and carry it on' that is being reappraised today through the lenses of local self-reliance and biodiversity. From here, we dig into the science, the conservation and the local practice, one layer at a time.
Sources & further reading
- Khoury et al. (2014) Increasing homogeneity in global food supplies and the implications for food security — PNAS
- Camacho Villa et al. (2005) Defining and identifying crop landraces — Plant Genetic Resources
- van de Wouw et al. (2010) Genetic erosion in crops: concept, research results and challenges — Plant Genetic Resources
- Tieman et al. (2017) A chemical genetic roadmap to improved tomato flavor — Science
- Nishio et al. (2016) Estimation of loss of genetic diversity in modern Japanese cultivars (Asian pear) — BMC Genetics
- Westengen et al. (2013) Global ex-situ crop diversity conservation and the Svalbard Global Seed Vault — PLOS ONE
- Ramirez-Villegas et al. (2022) State of ex situ conservation of landrace groups of 25 major crops — Nature Plants
- Raggi et al. (2024) Landrace in situ (on-farm) conservation: European Union achievements — Biodiversity and Conservation
- Kloppenburg (2014) Re-purposing the master's tools: the open source seed initiative and seed sovereignty — Journal of Peasant Studies
- Vernooy et al. (2020) The role of community seed banks in achieving farmers' rights — Development in Practice
- Mimura (2024) Introduction to heirloom vegetables in Kyoto prefecture (Kyo-yasai), Japan — Journal of Ethnic Foods
- Uchiyama et al. (2017) Tradition and Japanese vegetables: history, locality, geography, and discursive ambiguity — Journal of Ethnic Foods
- Shirasawa et al. (2020) Genome sequence and analysis of 'Sakurajima Daikon' — DNA Research
- Galluzzi et al. (2010) Home gardens: neglected hotspots of agro-biodiversity and cultural diversity — Biodiversity and Conservation
- Taylor & Lovell (2015) Urban home gardens in the Global North (ethnic and migrant gardens, Chicago) — Renewable Agriculture and Food Systems
- Dream of Wild Health — Native-led nonprofit conserving Indigenous seeds (Minneapolis)
- FAO (2014) Genebank Standards for Plant Genetic Resources for Food and Agriculture
Everything above is free to read.
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