Camellia sinensis is an evergreen plant native to China and southeast Asia. In describing what a tea plants look like, there’s a big difference between how it grows in the wild and how it grows in cultivation on tea plantations. We’ll distinguish between these as much as possible as we go along.
Regardless of whether it's the China or Assam bush or where it grows, the plant’s leaves are simple; that is, a single, individual leaf vs. one consisting of multiple leaflets. They grow alternately (not directly across from one another on the plant’s stem), have serrated edges, taper to sharp points at their tips, and are otherwise smooth. Botanically this is written as alternate, serrate, acuminate, and glabrous.
While fairly insignificant when compared with those of its relative the garden camellia (Camellia japonica), tea's flowers are nonetheless attractive. They range from white to light pink in color, are about an inch (2½ cm.) in diameter, have five to seven petals and sepals, and are fragrant.
A brownish green fruit develops from the flower that measures about an inch (2½ cm.) in diameter. Between 1–5 seeds are held inside a fruit capsule, each of which is dark brown, smooth, and about ½" (1.25 cm.) in diameter.
The two primary varieties (Camellia sinensis var. sinensis and Camellia sinensis var. assamica) hybridize easily with one another in the wild. As a result, a wide range of variation exists that may stray from or overlap the following descriptions of the differences between the China and Assam bushes.
The China bush has a shrubby habit, with its branches sprouting from the base in a vertical fashion. The shrub naturally grows into a dome shape to heights of 20' (6.1 m.), but on tea plantations it is most often pruned to keep it shorter and sheared to a flat “table-top.” Both are techniques that make for easier plucking at harvest time.
The leaves of Camellia sinensis var. sinensis are the smaller of the two varieties. They typically range from 1¼–4¾" (3–12 cm.) long and ½–2" (1–5.5 cm.) wide. Leaves are thick, maturing to a dark green. Harvests from the China bush are somewhat small as well, owed in part to their small leaf size. The China bush is considered to produce the best leaves for fancy green teas, high quality black teas, and oolongs.
The Assam bush has a more tree-like form than that of China bush. It usually displays a distinct trunk and somewhat open branching. In the wild these plants can grow 32–50' (9.8–15 m.) tall and have a crown width of about 16' (5 m.). In addition to being taller than the China bush, their leaves are also larger at maturity, ranging between 3–6" (8–16 cm.) long and 1–2.25" (2.5–6 cm.) wide. Their leaves are not as sharply serrated (toothed) as those of the China bush.
Assam bushes grown for tea production are also pruned to control
their height and to form a plucking table; however their large leaves remain a
dominant feature. This variety is
sometimes also referred to as large-leaf tea.
The Assam bush is used to produce many fine, robust black teas including the very distinctive pu'erh tea.
The China and Assam bushes are each suited to grow better in different places, with both producing great teas. Factors other than plant variety are much more important in determining a luscious cup of tea.