Gonocarpus tetragynus is an Australian herb in the watermilfoil family Haloragaceae native to eastern Australia.[1] Common names include common raspwort.[2] It is a widespread species particularly found in dry eucalyptus forests, scrubland, and heathland.[1]
The wiry stems and opposite leaves of Gonocarpus tetragynusThe even covering of white appraised hairs on the leaves and the stem
The herb can grow erect or ascend to 15-30 cm (5.9-11.8 in) tall. The many wiry branching stems can be smooth or are weakly 4-ribbed. Leaves are decussate, lanceolate and range from 0.6-1.2 cm (0.2-0.5 in) long. The leaf margins are thickened, irregularly toothed and recurved. The leaves are attached to petioles, 0.5-1 mm (0.020-0.039 in) long. The bracts are sessile, alternate, lanceolate, and range from 2-2.5 mm (0.079-0.098 in) long. The bracteoles are membranous, lanceolate to linear-lanceolate, 0.8-1.2 mm (0.031-0.047 in) long.[3] Both the leaves and the stem are covered in white-appressed hairs, which gives a rough texture.[3][4]
The inflorescence of Gonocarpus tetragynus after flowering
The species is perennial.[3][4] The flowers are bisexual, but in the occasional individual, they become functionally female, after the abortion of the stamens and the petals.[3] The flowering time ranges from spring to summer; as early as September and as late as February.[3][4][5] The inflorescence is a spike with tiny solitary flowers which are 1-3 mm (0.039-0.12 in) across.[3][4] Like in other members of the Haloragaceae family, the flowers are divided into four whorls. The sepals are deltoid and green, with a prominent basal callus. Petals range from green to red and are hooded and keeled. The herb has eight stamens and an 8-ribbed ovary.[3]
The fruit is a dry nut, a family characteristic.[3] The herb develops a ridged, globular nut.[3][4] It is 1-1.3 mm (0.039-0.051 in) long.[3] The colour ranges from silver-grey to slate grey.[3]
Taxonomy
Jacques Labillardière first formally described the species as G. tetragyna in 1805, as published in Novae Hollandiae Plantarum Specimen 1.[6] Its variant, Gonocarpus tetragynus, was the accepted name by 2005, according to the Australian Plant Census of the same year.[6]
Several other synonyms are known, including Goniocarpus tetragynus, Haloragis gonocarpus, Haloragis tetragyna, Halorrhagis tetragyna, Gonocarpus tenellus, Haloragis rubra, Halorrhagis rubra.[6]
Distribution and habitat
The species is widespread, in terrestrial Eastern Australia. It occurs in Queensland, New South Wales, ACT, Victoria, South Australia, and Tasmania.[3] The herb can also be found in the Flinders and Clarke islands in the Bass Strait.[3] While widespread it is particularly found in moist to dry soils in dry Eucalyptus forests, shrublands, and heathlands.[1] In Tasmania, it is commonly found on dry stony outcrops.[4]
Records of this species in other countries are based on miss identification of G. incanus, G. montanus, G. chinensis, and G. philippinensis.[3]
Distinguishing from similar species
Gonocarpus tetragynus is similar in appearance to Gonocarpus humilis. The two species can be distinguished by the former's lanceolate leaves, an even cover of white-appraised hairs and the flower's eight stamens.[3]
Cultivation
Cultivation of the species is possible, but it is not widely grown.[4]
References
1 2 3 Peter G. Wilson. "Gonocarpus tetragynus". PlantNET - New South Wales Flora Online. Royal Botanic Gardens & Domain Trust, Sydney Australia. Retrieved 2 August 2014.
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