The Assamica Plant
The complete reference on Camellia sinensis var. assamica, the large-leaf tea plant every cup certified by this office is made from. What it is, where it grows wild, the naming dispute that took taxonomists a century to settle, and how its chemistry builds the strong cup.
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Every cup this office certifies starts from one plant: Camellia sinensis var. assamica, the broad-leaf tea tree native to the Brahmaputra valley and the hill forests around it. It is one of two working varieties of the tea species, set apart from the small-leaf China plant, Camellia sinensis var. sinensis, by size, chemistry, and a name that took botanists more than a century to settle correctly. This record covers what the plant is, where it stands wild today, how it got its name, what its chemistry certifies about the cup, and the clones bred from it that now fill most of the region's gardens. The deeper stories, the 1839 discovery, the genetics of where tea itself began, the standing wild trees, sit in the linked accounts below.
What the plant is
Camellia sinensis is a single species with two principal working varieties, grown for two different jobs. Var. sinensis, the China plant, is a modest multi-stemmed shrub, 1 to 2 metres tall (about 3 to 6.5 feet) if left alone, with small, hard, leathery leaves 5 to 14 centimetres long (2 to 5.5 inches). Var. assamica is a different scale of plant entirely: left unpruned it grows as a small tree, 10 to 15 metres tall (about 33 to 50 feet) with a single trunk, sometimes taller still in the wild. Its leaves are broad, thin, and glossy10, 8 to 20 centimetres long and 3.5 to 7.5 centimetres wide (roughly 3 to 8 inches by 1.4 to 3 inches), several times the leaf area of the China plant, with a more pointed tip and clear marginal veining. No garden grows it at that height. Every bush in a commercial planting is the same tree species, kept down by pruning to a waist-high plucking table. A third working type sits between the two: the Cambod or southern form, a smaller, fastigiate tree 6 to 10 metres tall (about 20 to 33 feet) with leaves intermediate in size, found from Indochina down into the southern reaches of the tea belt. Botanist W. Wight set out the three-way split6 in 1962, and the trade still uses it. Var. assamica is the plant this record concerns. The other two are documented elsewhere.
| Type | Botanical name (Wight, 1962) | Growth form | Leaf | Range |
|---|---|---|---|---|
| China | Camellia sinensis | Multi-stemmed shrub, 1 to 2 m (3 to 6.5 ft) | Small, hard, leathery, 5 to 14 cm (2 to 5.5 in) | Southern and eastern China |
| Assam | Camellia assamica | Small tree, 10 to 15 m (33 to 50 ft), single trunk | Broad, thin, glossy, 8 to 20 cm (3 to 8 in) | Brahmaputra valley, Yunnan (separate lineage), northern Myanmar |
| Cambod (southern) | Camellia assamica subsp. lasiocalyx | Fastigiate small tree, 6 to 10 m (20 to 33 ft) | Intermediate size | Indochina, southern tea belt |
Where it stands wild
The plant did not arrive in the Brahmaputra valley by anyone's hand. It was already growing wild in the hill forests of upper Assam when Robert Bruce was shown it in 1823, part of a fuller story documented in The History of Assam Tea. Wild specimens are still being found today, unplanted stands in the forest tracts along the Assam-Arunachal-Nagaland border, some reaching heights that make clear this is a forest tree and not a garden shrub. Genetic testing of those standing trees has complicated the word "wild" itself: a real share of them already carry cultivated ancestry, pollen drift from the gardens having reached even the remote stands. The full account of that search, and what it does and does not settle, is in The Wild Tea Still Standing in Assam's Forests. A morphologically similar broad-leaf population also grows wild across the border in Yunnan, and the resemblance led decades of trade writing to call both "Assam type" tea, as though they were one plant with two addresses. The genetics say otherwise. Nuclear and chloroplast DNA place three separate domestication events7, not two, China's small-leaf plant, Yunnan's own big-leaf wild population, and Assam's, each raised into cultivation independently by its own people. The deep split, back to the last ice age, some 22,000 years ago, is the one separating China's plant from the whole Assam-type lineage. Assam's assamica and Yunnan's Assam-type tea parted ways from each other far more recently than that, only about 2,770 years ago, long after each had already gone its own way from China's plant. That case is documented in full in The "Assam Type" Tea Growing in China Is Not Your Assam Tea.
The name, and the century it took to settle it
A plant this consequential should have an easy name. It does not. The naturalist most readers credit, J.W. Masters, described the Assam plant in detail for the Agricultural and Horticultural Society of India in 1844 and called it Thea assamica. That name is the one still repeated most often. It also has no formal standing: Masters himself refused to stand behind it, writing in the same paper that the label was used only for convenience and that the plant showed nothing to justify burdening science with a new name, and a name its own author disclaims does not count as validly published. The botanist Jacques Denys Choisy validly published Thea viridis var. assamica5 in 1855, splitting the species into three varieties by leaf length after seeing specimens from Kew. Pierre recombined it as Thea chinensis var. assamica in 1887, still within the genus Thea, and the Japanese botanist Siro Kitamura moved it into Kuntze's already-settled genus Camellia in 1950, publishing Camellia sinensis var. assamica, though even his own citation of the authority behind it carried an error later taxonomists had to correct. A dedicated 2017 taxonomic paper2 worked through that correction in detail, and a 2021 follow-up3 settled it further back: the International Plant Names Index4 now records the correct combination as Camellia sinensis var. assamica (Royle ex Hook.) Steenis, with Kitamura's 1950 version standing as a later isonym. Nobody is still arguing over what the plant is. The dispute was not only about paperwork. The Company's own scientific commission argued in 1836 over whether the wild plant was true tea at all, and two of the three experts sent to certify it said no. The plant they doubted is the one growing in nearly every garden in the valley today, a story told in full in The Plant the Company's Own Scientists Called Savage.
The chemistry behind the strength
Strength is what this office grades Assam on, and strength is chemistry, not opinion. Fresh assamica leaf runs higher in caffeine9 than the China plant, on the order of 4 percent against roughly 3.1 percent by dry weight in comparative sampling, and it carries a heavier load of simple catechins to begin with. Those catechins are the raw material full oxidation acts on: crushed and fully oxidised, as Assam always is, they polymerise into theaflavins, the compounds behind the reddish colour and the bracing edge this office calls briskness, and thearubigins, which build the body and the deep copper liquor. More catechin going in means more theaflavin and thearubigin coming out, which is why a fully-oxidised assamica leaf produces a stronger, thicker cup than the same treatment gives the China plant. It is also why the leaf suits CTC processing so well: a method built to maximise cell rupture and full oxidation gets the most out of a leaf already stocked for it. How CTC does that mechanically, and how it differs from orthodox manufacture, is documented in CTC vs. Orthodox; why that same chemistry is what lets the cup take milk without thinning out is documented in Milk and Assam.
From wild bush to garden clone
At the genetic level the plant is a diploid, 30 chromosomes carried as 15 pairs, and its genome runs to roughly 3 gigabases, sequenced end to end in 20248 from the cultivar TV1, the oldest clone Tocklai ever released, first put out in 1949 and still widely planted. Before clonal selection, Assam's gardens were planted almost entirely from open-pollinated seed, what growers still call Assam jat, descended from the same wild population Bruce first saw. Every seed-grown bush was a slightly different genetic draw, useful for resilience but unpredictable to manage. From the mid-20th century, Tocklai began selecting individual mother bushes for yield, vigour, and cup quality and propagating them by cutting rather than seed, the vegetative clones (TV numbers) that fill most modern plantings. A third stock, bred by deliberately crossing two chosen clones and planting the resulting hybrid seed rather than a single mother's cuttings, gives growers some of a clone's selected quality with more of seed jat's genetic variation. Both paths are laid out in Assam Tea Clones and The Third Way to Plant an Assam Tea Bush. Every one of those clones, the seed jat still standing in some old gardens, and the plant Bruce was shown in 1823 are the same tree, Camellia sinensis var. assamica, bred toward different ends but never toward a different species.
Assamese-language coverage11 of the region's tea history puts Assam's output at more than half of all the tea India makes, grown across several hundred gardens, the plant's own numbers standing behind every verdict this office hands down on the strength of the cup.