Tetracarpaea tasmannica
Name: Tetracarpaea refers to the four conspicuous and separate carpels.
Region: Tasmania.
Habitat: subalpine areas.
Botany
Evergreen, glabrous, erect, bushy, beautiful, little shrub; from 15 to 100 cm.
Leaves: shiny; small; with prominent veins and end near the margin; elliptic to oblanceolate; ± 25 mm long and 8 mm wide; petiole about 2 mm long; margins are serrate or crenate; epidermis is covered by a thick cuticle.
Inflorescences: dense, erect, terminal racemes, up to 5 cm long.
Flowers: small, white; bisexual, actinomorphic, and 5 to 10 mm wide; crowded at the ends of the branches; blooming in autumn; 4 sepals persist to the maturity of the fruit; 4 petals are white and spatulate in shape; stamens are 4 and opposite or 8; anthers are basifixed; ovary is superior, with 4 large carpels, usually separate, occasionally 2 or 3 fused at the base, or rarely halfway up, erect and stipitate, with a suture along the ventral side; placenta runs along each side of the suture and bears 1 to 3 rows of numerous, tiny ovules; ovules have one integument or two; ovary hardly enlarges after anthesis.
Fruit: of 4 follicles; joined at the base.
Seeds: numerous; ±.5 mm long.
Taxonomy
Tetracarpaea has an odd mix of characters, and its affinities remained obscure. It is the only genus in the flowering plant family Tetracarpaeaceae. William Jackson Hooker placed it near Cunoniaceae. George Bentham also placed it in the Cunoniaceae, but later
moved it to Escalloniaceae. Adolf Engler put Tetracarpaea in Saxifragaceae, including Escalloniaceae.Later most authors put Tetracarpaea in Cunoniaceae, Escalloniaceae, or Saxifragaceae. Takenoshin Nakai put Tetracarpaea in its own family Tetracarpaeaceae. Arthur Cronquist put Tetracarpaea in Grossulariaceae. Armen Takhtajan has at different times put Tetracarpaea in Escalloniaceae and in Tetracarpaeaceae. Matthew H. Hils concluded that Tetracarpaea was much closer to Saxifragaceae than to Cunoniaceae or Escalloniaceae. Phylogenetic analysis of DNA sequences has shown that Tetracarpaea is a member of the Haloragaceae alliance, an informal group composed of the families Aphanopetalaceae, Tetracarpaeaceae, Penthoraceae, and Haloragaceae in the order Saxifragales.
Taxonomy
Hooker named Tetracarpaea and placed it in Cunoniaceae. George Bentham moved Tetracarpaea from Cunoniaceae to Escalloniaceae. Adolf Engler put Tetracarpaea in Saxifragaceae. Takenoshin Nakai put Tetracarpaea in its own family Tetracarpaeaceae. John Hutchinson placed it in Escalloniaceae. Arthur Cronquist put Tetracarpaea in Grossulariaceae. Armen Takhtajan has at different times put Tetracarpaea in Escalloniaceae and in Tetracarpaeaceae.