| Theaceae | |
|---|---|
 | |
| TeaCamellia sinensis | |
Scientific classification | |
| Kingdom: | Plantae |
| Clade: | Tracheophytes |
| Clade: | Angiosperms |
| Clade: | Eudicots |
| Clade: | Asterids |
| Order: | Ericales |
| Family: | Theaceae Mirb. (1816)[1] |
| Genera | |
See text | |
| Synonyms | |
Camelliaceae[2] | |
Theaceae (/θiˈeɪsii/), thetea family, is afamily offlowering plants comprising shrubs and trees, including the economically importanttea plant, and the ornamentalcamellias. It can be described as having from seven to 40genera, depending on the source and the method of circumscription used. The family Ternstroemiaceae has been included within Theaceae;[3][4] however, theAPG III system of 2009 places it instead inPentaphylacaceae.[5] Most but not all species arenative to China and East Asia.
Plants in this family are characterized by simple leaves that are alternate spiral to distichous, serrated, and usually glossy. Most of the genera haveevergreen foliage, butStewartia andFranklinia aredeciduous. The toothed margins are generally associated with a characteristic Theoid leaf tooth, which is crowned by a glandular, deciduous tip.[6] The flowers in this family are usually pink or white and large and showy, often with a strong scent.[7] The calyx consists of five or more sepals, which are often persistent in the fruiting stage, and the corolla is five-merous, rarely numerous. Plants in Theaceae are multistaminate, usually with 20-100+ stamens either free or adnate to the base of the corolla, and are also distinctive because of the presence of pseudopollen. The pseudopollen is produced from connective cells, and has either rib-like or circular thickenings. The ovary is often hairy and narrows gradually into the style, which may be branched or cleft. The carpels are typically opposite from the petals, or the sepals in the case ofCamellia. The fruits areloculicidal capsules, indehiscentbaccate fruits or sometimespome-like. The seeds are few and sometimes winged, or in some genera covered by fleshy tissue or unwinged and nude.[4][6]
Eight genera are currently accepted:[1]
The fossilPentapetalum trifasciculandricus, about 91 million years old, may belong to the Theaceae or the Pentaphylacaceae.[8]
Members of the family are found in Southeast Asia and Malesia, tropical South America and the Southeast United States. Three genera (Franklinia,Gordonia andStewartia) have species native to the Southeast United States, withFranklinia beingendemic there, and under some interpretations, alsoGordonia with the Asian species formerly included in that genus being transferred toPolyspora.[9]
There is distinctive chemistry within the family Theaceae. Sometimes, single crystals of calcium oxalate are present in Theaceous plants.Ellagic acid and common polyphenols including flavonols, flavones and proanthocyanins are widely distributed throughout the family.Gallic acid andcatechins only occur inCamellia sect.Thea (C. sinensis, C. taliensis andC. irrawadiensis.) Caffeine and its precursors theobromine andtheophylline are only found in sect.Thea and are not found in other species ofCamellia or other Theaceae. Caffeine content in the tea bush makes up 2.5-4% of the leaf's dry weight, and this high content of catechins and caffeine in the tea bush is the result ofartificial selection by humans for these characters. Triterpenes and their glycosides (saponins) are found widely throughout the family in the seeds, leaves, wood and bark. Plants in this family are also known to accumulate aluminum and fluoride.[4]
The best knowngenus isCamellia, which includes the plant whose leaves are used to producetea (Camellia sinensis). In parts of Asia, other species are used as a beverage, includingC. taliensis, C. grandibractiata, C. kwangsiensis, C. gymnogyna, C. crassicolumna, C. tachangensis,C. ptilophylla, andC. irrawadiensis.[10] Severalspecies are grown widely as ornamentals for their flowers and handsome foliage.
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