The Assamica Plant
The complete reference on Camellia sinensis var. assamica, the large-leaf tea plant. What it is, where it grows wild and the naming dispute that took taxonomists a century to settle.
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Camellia sinensis var. assamica is 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.
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 multi-stemmed shrub, 1 to 2 metres tall (about 3 to 6.5 feet) if left alone, with small, hard, leathery leaves 4 to 14 centimetres long (about 1.5 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). Its leaves are broad, thin, and glossy, 8 to 20 centimetres long and 3.5 to 7.5 centimetres wide (roughly 3 to 8 inches by 1.4 to 3 inches), 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 in Indochina. Botanist W. Wight set out the three-way split6 in 1962.
| Type | Botanical name (Wight, 1962) | Growth form | Leaf |
|---|---|---|---|
| China | Camellia sinensis | Multi-stemmed shrub, 1 to 2 m (3 to 6.5 ft) | Small, hard, leathery, 4 to 14 cm (about 1.5 to 5.5 in) |
| Assam | Camellia assamica | Small tree, 10 to 15 m (33 to 50 ft) | Broad, thin, glossy, 8 to 20 cm (3 to 8 in) |
| Cambod (southern) | Camellia assamica subsp. lasiocalyx | Fastigiate small tree, 6 to 10 m (20 to 33 ft) | Intermediate size |
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 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. Nuclear and chloroplast DNA place three separate domestication events7, China's small-leaf plant, Yunnan's own big-leaf wild population, and Assam's, each domesticated independently. Assam's assamica and Yunnan's Assam-type tea parted ways about 2,770 years ago. 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
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. Masters's own 1844 use of it 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. 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. Pierre recombined it as Thea chinensis var. assamica in 1887, still within the genus Thea. In 1949 the Dutch botanist C.G.G.J. van Steenis moved it into Camellia, publishing Camellia sinensis var. assamica. The Japanese botanist Siro Kitamura published the same combination in 1950, and his 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. A 2021 follow-up3 found Thea assamica validly published in 1847, in William Hooker's guide to Kew, which credited the name to John Forbes Royle. The International Plant Names Index4 now gives Royle ex Hooker's 1847 Thea assamica as the basionym.
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
Fresh assamica leaf runs higher in caffeine9 than the China plant. Catechins are the raw material full oxidation acts on: crushed and fully oxidised, they polymerise into theaflavins, the compounds behind the reddish colour and the bracing edge called briskness, and thearubigins, which build the body and the deep copper liquor. 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
The plant's genome was assembled at chromosome scale in 20248 from the cultivar TV1, which Tocklai released in 1949.
Before clonal selection, Assam's gardens were planted almost entirely from open-pollinated seed, what growers still call Assam jat. 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.