Seeds
SeedCounter began by counting orchid seeds, which look like dust, and today it measures grass, soybean, corn, rice, coffee and beans. Here is each one in full, from plant to seed, with the weight it carries in Brazil and what the orchid research group (GPEOrq) and the seed research group (GPSEM) study on it.
01 · Pasture
When people think of crops, soybean and sugarcane come to mind. On the map, grass takes up the most land: 165.6 million hectares of pasture in 2025, about a fifth of the country's territory. That is three times the area of soybean and sugarcane combined.
Area occupied in Brazil, in millions of hectares
Urochloa brizantha
Cultivars such as Marandu and Piatã cover much of the country's pasture. The unit that is bought and planted is the spikelet: the caryopsis still enclosed in its glumes. That is why a grass test report counts full and empty spikelets, and not just viable and non-viable seeds.
Megathyrsus maximus
The former Panicum maximum, with cultivars such as Mombaça, accounts for about a quarter of the forage seeds produced in Brazil. Between 2013 and 2017, Marandu and Mombaça occupied almost half of the fields planted only to produce grass seed.
At the group's bench
Restoring degraded pasture became public policy in 2023, with the national program for converting degraded pastures (Decree 11,815). And every renewed pasture starts with a seed lot, which has to arrive ready to germinate.
That is where GPSEM works. Prof. Ceci studies the tetrazolium test in tropical forage grasses, which tells dormant seeds from non-viable ones; the dormancy that breaks during storage; and near-infrared to read a seed lot without destroying the seed. Prof. Nelson coordinates GPMeF, the forage research and breeding group.
02 · Orchid
An orchid seed weighs 0.31 to 24 millionths of a gram and measures 0.05 to 6 mm. A single fruit can release up to 4 million of them. It has no endosperm, the reserve that feeds the embryo in other seeds, and in nature it only germinates with the help of a fungus.
The group's work
For a long time it was said that orchid seeds do not last long in storage. GPEOrq and GPSEM dried seeds of eight Cattleya species to about 3% moisture content and stored them at −18 °C in a conventional seed bank. After 13 to 14 years, all of them germinated again. With a sucrose pretreatment, seven exceeded 90% germination.
The authors' calculations estimate how long it would take until only half of the seeds were still viable: about 30 years in six species, 82 years in C. granulosa and 110 years in C. harrisoniana. Even without sucrose, the estimate for C. harrisoniana is more than 60 years. The longest-lived seeds had less air around the embryo.
Francisqueti A.M., Marin R.R., Hengling M.M., Hosomi S.T., Pritchard H.W., Custódio C.C., Machado-Neto N.B. (2024). Orchid seeds are not always short lived in a conventional seed bank! Annals of Botany 133(7), 941–952. doi:10.1093/aob/mcae021
Years stored at −18 °C
A network of seed banks
Between 2007 and 2010, the OSSSU network of orchid seed banks brought together more than 20 institutes from 15 countries, led by Kew. It stored seeds of 386 species, 54% above the target, and created in-flask germination protocols for 239. Prof. Nelson was part of the network, and the group's seed bank follows the same path.
03 · Crops
Soybean, corn, rice and coffee appear in the examples and in the Theory section. Each has its own shape, and the shape decides how the outline is found: soybean is round and sits apart, rice is long, coffee has a flat side.
180.4 million t on 48.6 million ha in the 2025/26 crop year, according to Conab
Soybean associates with Bradyrhizobium bacteria in its roots and receives nitrogen from them. Embrapa estimates this saves more than $10 billion a year in fertilizer.
Soybean quality classes
144 million t on 22.6 million ha in the 2025/26 crop year, according to Conab
The corn kernel is a one-seeded fruit, the caryopsis. The endosperm, where the starch is, makes up about 82% of it.
1,200 corn seeds germinating
11.1 million t on 1.52 million ha in the 2025/26 crop year, according to Conab
Rice seed comes with its hull: two modified leaves, the lemma and the palea, which make up about 20% of the grain's mass.
40 rice grains in the mean seed shape
67.6 million 60 kg bags in the 2026 crop, according to Conab
The bean that goes to the roaster is the seed, and each fruit usually has two. Dried, it dislikes cold: it sits between seeds that tolerate drying and seeds that do not.
28 coffee beans in the mean seed shape
2.95 million t on 2.54 million ha in the 2025/26 crop year, according to Conab
The commercial classes come from the seed coat color: carioca, black, striped, bolinha, rosinha. It is the kind of class an image reads well.
04 · From dust to coco de mer
The smallest seed in Kew's seed bank measures 0.07 mm. The largest in the plant kingdom reaches half a meter. Change the window width and see which ones fit at each scale, always at their true size relative to one another.
| Seed | Length | Where the number comes from |
|---|---|---|
| Bletilla striata, orchid | 0.07 mm | Kew, the smallest in the Millennium Seed Bank |
| Cattleya, orchid | 0.68 mm | Measured by GPEOrq on the scanner, median |
| Signal grass, spikelet | 4.8 mm | Measured on the USDA photo, from the 1 mm scale bar |
| Soybean | 7.7 mm | Measured by the app on a public soybean dataset, median |
| Rough rice | ≈ 8 mm | Typical value |
| Coffee | ≈ 10 mm | Typical value |
| Corn | ≈ 11 mm | Typical value |
| Bean | ≈ 11 mm | Typical value |
| 1 real coin | 27 mm | For comparison, the same coin as in the seeds-on-a-coin post |
| Coco de mer | up to 500 mm | Kew, the largest seed in the world |
05 · Fun facts
Seeds that wake up after centuries, vaults inside mountains and a test that stains red whatever is viable. Every number has its source.
A date palm seed found at Masada, in Israel, dated to between 155 BCE and 64 CE, germinated in 2005. The palm was nicknamed Methuselah.
Sallon et al. 2008, Science
A sacred lotus seed almost 1,300 years old, found in the dry bed of a lake in northeastern China, was germinated by Jane Shen-Miller's team in California.
UCLA; Shen-Miller et al. 1995, Am. J. Bot.In 1879, William Beal buried 20 bottles of seeds in Michigan. The one opened in 2021 still had viable Verbascum seeds. The next comes out of the ground in 2040, and the experiment runs until 2100.
MSU Today, 2023Russian researchers regenerated Silene stenophylla plants from fruit tissue stored in Siberian ice. Whole seeds did not germinate: the plants came from tissue culture.
Yashina et al. 2012, PNAS
The coco de mer seed, from a palm of the Seychelles, can weigh up to 25 kg and measure half a meter.
Kew, 2020The smallest seeds in the Millennium Seed Bank come from a Chinese terrestrial orchid, Bletilla striata. About fourteen would fit lined up along one millimeter of ruler.
Kew, 2025As many as 4 million seeds have been counted in a single orchid capsule. Counting a plate of them by hand is the problem that gave rise to SeedCounter.
Arditti and Ghani 2000, New PhytologistA hundred soybean seeds weigh 13 to 20 g. A thousand orchid seeds weigh 0.3 to 24 milligrams: to match the weight of a hundred soybean seeds, it would take some 540,000 to almost 67 million of them.
Embrapa; Arditti and Ghani 2000
Open since 2008 inside a mountain in Norway, it holds more than 1.4 million seed samples at −18 °C. It has room for 4.5 million.
Crop TrustKew's seed bank in England holds almost 2.5 billion seeds of more than 40,000 species, dried and then kept at −20 °C.
Kew, 2025Embrapa's base collection, in Brasília, holds more than 120,000 seed accessions in long-term storage, from more than 1,100 species.
Embrapa, via Revista Cultivar, 2023The tetrazolium test originated with Georg Lakon, in Germany. In Brazil, Embrapa Soja has given more than 90 courses on the test since 1984, to more than 2,200 professionals.
França-Neto and Krzyzanowski 2019, J. Seed Sci.ISTA, the International Seed Testing Association, was founded in Cambridge, England, by 26 countries.
ISTAE. H. Roberts used the term recalcitrant for seeds that die if they dry out. Araucaria, cacao, juçara palm and rubber tree are among them.
Barbedo and Bilia 1998, Scientia AgricolaIn grasses, what falls from the plant, the thing we call a seed, is a caryopsis, the fruit, often still wrapped in the glumes, lemma and palea.
Filgueiras 1986, Pesq. Agropec. Bras.Credits and sources
The plant photos are by third parties under open licenses, and each one credits its author in the caption. The numbers come from MapBiomas, Conab, IBGE, Embrapa, Kew and the papers cited on each card.
Openly licensed photos from Wikimedia Commons, iNaturalist and USDA PLANTS, resized and converted to WebP. Photos marked as real with no credit come from GPEOrq and GPSEM.
Orchid, grass, soybean or anything that fits on a plate: count, measure and check in the browser.
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