Turkish çay and Russian чай are the variations on the theme of chá. In Min Nan, the same word is pronounced as tê; thanks to the Dutch East India Company, this plant and drink is known in Europe as tea.
荼 can refer to one of several types of bitter tasting vegetables. Early Chinese texts are rather vague in their description. This makes it difficult to determine which species it originally referred to.Whatever is real origin of the character, I prefer thinking of it as a slightly scrambled doodle of a traditional Chinese tea house.