A Botanical Perspective on Tea

By Nadia Cavallin, Field Botanist, Royal Botanical Gardens.

I love tea so, as a botanist, it’s funny that I had not considered the plant much. We often examine the tiniest intricacies of wild plants and sometimes ignore the popular agricultural plants, other than to make a game of how much evolutionary diversity we can get on a dinnerplate by counting the number of plant families from which the plants composing our meal came. (Yes, it really is a game.)  As a self-proclaimed nerd of food gardening, I spend many winter hours pouring over seed catalogues, admiring the diversity of varieties available for all the food plants we can grow here in Ontario, and possibly preparing an overly ambitious order list. Perhaps it’s because I can’t grow Camellia sinensis, the tea plant, that I’ve paid so little attention to it.  Given that it’s the plant that provides me my (thrice) daily beverage and my caffeine fix, it’s time to change that. Here’s a close look at Camelia sinensis from the same perspective with which I would see the plants along RBG’s trails.

Short of having the live plant to observe or an herbarium specimen to examine, a botanist’s way to learn the details of plant species is to consult a Flora, which is a publication describing the plants of a given region. Luckily, the Flora of China is available online (www.eFloras.org). Here, we learn that Camellia sinensis is an evergreen shrub or small tree, growing from one to nine meters tall. Its leathery leaves attach alternately along the stems. That is, at any point on a twig where you see a leaf, there will be only one leaf. The next leaf will be further along the twig. The leaves would look smooth, shiny, and dark green. However, if you were to stand upside-down and view the shrubs from the bottom, thus observing the undersides of the leaves, they would appear pale green. If the underside were smooth, then you would likely be in northern China, practicing your handstand by a shrub of Small Leaf Tea, Camellia sinensis variety sinensis. On the other hand, if your view were of pale backsides of leaves with a dense covering of long, soft, and curly spreading hairs, then you would more likely be in the southern part of the range the tea plant, among Large Leaf Tea, Camellia sinensis variety assamica. If so, I hope you might find a few fermented (young) leaves, a cup, and some boiling water to brew a cup of Pu’ehr tea.  Perhaps return to an upright position for this. Don’t worry about the hair. In botanical terms, long just means you don’t need a magnifying lens to see it.

While you savour your cup of tea, take a moment to admire the flowers. Small Leaf Tea blooms from October to December. I hope your tea is hot. Large Leaf Tea blooms from December to February. The flowers for both varieties grow from the axils of the leaves, either singly or in groups of two or three. They are about 2.5 to 3.5 cm in diameter, or the size of a loonie to a little bit bigger, each on a recurved stalk one half to one centimetre long. Each flower has six to eight round white petals framing a centre of many stamens with yellow anthers. In the centre of the stamens, you would find a round ovary that will mature into a three-lobed capsule. Capsules are dry fruits that split open when they are mature. Each lobe splits lengthwise along the middle to release a round seed, about 1 cm in diameter.

As you continue to sip your tea, you notice a purplish to reddish hue to the young twigs. Maybe your next cup of tea will be Kukicha, made with a mixture of twigs and leaves. Now tuned in to the importance of hair on plants, you notice a very fine coat of short white hairs on the twigs, and then the silvery grey, silky hairs on the buds terminating the twigs. These are the buds that will produce the next shoot, or if they are picked first, the next tea harvest.

Whichever of the thousands of varieties of tea that you enjoy, they all come from the beautiful broad-leaved evergreen shrub (or small tree), Camellia sinensis. The magnificent diversity comes from the complex interplay of environment, millennia of cultivation, and skilled processing of the leaves and buds. We currently know very little about the wild plants from which we cultivate our beloved tea, but scientists are on it.