Grey germander
Teucrium racemosum in the Royal Botanic Gardens, Cranbourne
Scientific classification Edit this classification
Kingdom: Plantae
Clade: Tracheophytes
Clade: Angiosperms
Clade: Eudicots
Clade: Asterids
Order: Lamiales
Family: Lamiaceae
Genus: Teucrium
Species:
T. racemosum
Binomial name
Teucrium racemosum
Habit

Teucrium racemosum, also commonly referred to as either the grey germander[2] or forest germander,[3] is a species of flowering plant in the family Lamiaceae. It is endemic to Australia and is found in all mainland states, the Northern Territory and the Australian Capital Territory. It grows in floodplains, dry lake beds and open woodlands. A perennial herb, it has four-sided, densely hairy stems, narrow egg-shaped leaves, and white flowers usually arranged singly in leaf axils. It grows to be between 15 and 40 cm tall.

Description

Teucrium racemosum is a perennial herb that grows to a height of between 15 and 40 cm (5.9 and 15.7 in). It is a root suckering plant, meaning that it spreads by pushing up new shoots around the perimeter of its original base. Due to this root suckering ability, it is not uncommon for the Teucrium racemosum to spread to a diameter of several metres. The stems are white or greyish and densely covered with curved hairs pressed against the stem but that are usually lost from the stem's ridges. The leaves are a narrow oval shape, densely hairy, especially on the lower surface, usually 10–20 mm (0.39–0.79 in) long and 2–6 mm (0.079–0.236 in) wide. The edges of the leaves are sometimes somewhat lobed, rolled under or wavy. The flowers are usually arranged singly in leaf axils near the ends of branches on a pedicel that is 5–18 mm (0.20–0.71 in) long. The pedicel is often horizontal near its far end with the flower held erect. The sepals are 3–6 mm (0.12–0.24 in) long, densely hairy and fused at the base for about half of their length. The petals are 8–14 mm (0.31–0.55 in) long, with the lower middle lobe usually 5–9 mm (0.20–0.35 in) long, the four stamens 8–14 mm (0.31–0.55 in) long. Flowering occurs from September to June.[2][3][4][5][6]

Taxonomy

Teucrium racemosum was first described in 1810 by Scottish botanist Robert Brown in Prodromus Florae Novae Hollandiae.[7] Teucrium is a genus of the family Lamiaceae. The genus Teucrium was first described by Carl Linnaeus in his work Species Plantarum in 1753.[8] Teucrium has around 300 species, of which 13 are endemic to Australia.[9]

Distribution and habitat

Teucrium racemosum is found in all states and territories of Australia apart from Tasmania.[3] It grows on floodplains, dry lake beds and open woodlands. It is also often found around ephemeral lakes or disturbed areas.[3][10] also often found around ephemeral lakes or disturbed areas that are usually uninhabitable for most other plants.[3]

Reproduction

As is the case with many Lamiaceae, Teucrium racemosum uses gynodioecy as a method of reproduction.[11] Gynodioecy is a breeding system consisting of male and hermaphroditic plants in a population.[12] Gynodioecy occurs as a consequence of genetic mutation that prevents a hermaphroditic plant from producing pollen, while keeping the female reproductive parts intact.[13] In gynodioecious species, female plants often have much smaller anthers (the part of the stamen where pollen is produced) and as a result produce little to no pollen, whilst in hermaphroditic flowers both male and female sexes are functional.[14] Genetic conflict often arises in these plants, and it is a common observation for female plants to produce more seeds and healthier, higher quality seed than the hermaphroditic plants.[15] This is thought to be because of the extra energy that female plants have access to as a result of not producing pollen.[14] Gynodioecy is an extremely rare form of reproduction, with the Teucrium racemosum being part of just 1% of all plants that exhibit a gynodioecious mating system.[16] Flowering occurs from September to June.[3]

Conservation

Teucrium racemosum is listed as "not threatened" by the Western Australian Government Department of Parks and Wildlife, and as "least concern" under the Queensland Government Nature Conservation Act 1992 and the Northern Territory Government Territory Parks and Wildlife Conservation Act 1976.[17][18][19]

See also

References

  1. ↑ "Teucrium racemosum". Australian Plant Census. Retrieved 16 May 2021.
  2. 1 2 Conn, Barry J. "Teucrium racemosum". Royal Botanic Gardens Victoria. Retrieved 22 May 2021.
  3. 1 2 3 4 5 6 Conn, Barry J. "Teucrium racemosum". Royal Botanic Garden Sydney. Retrieved 22 May 2021.
  4. ↑ "Teucrium racemosum". Botanic Gardens of South Australia. Retrieved 22 May 2021.
  5. ↑ "Teucrium racemosum". State Herbarium of South Australia. Retrieved 22 May 2021.
  6. ↑ Toelken, Hellmut R. (1985). "Notes on Teucrium L. (Labiatae)" (PDF). Journal of the Adelaide Botanic Gardens. 7 (3): 295. Retrieved 22 May 2021.
  7. ↑ Prodromus florae Novae Hollandiae et insulae Van-Diemen, Brown R., 1810 p. 1802-1805
  8. ↑ Species Plantarum, Linnaeus C., 1753, p. 562, retrieved 12 May 2021
  9. ↑ "Genus Teucrium". Royal Botanic Garden Sydney. Retrieved 22 May 2021.
  10. ↑ Teucrium racemosum - Plant Selector, 2021, Botanic Gardens of South Australia, http://plantselector.botanicgardens.sa.gov.au/Plants/Details/2879
  11. ↑ Floral Construction and Pollination Biology in the Lamiaceae, Claßen-Bockhoff R., Annals of Botany, 2007, 100 (2), p. 350-360,https://doi.org/10.1093/aob/mcm157
  12. ↑ Gynodioecy in Teucrium racemosum, O'Brian E.& Walsh P., 2013, Muelleria, Volume 31, p. 77-80
  13. ↑ A Model for the evolution of Dioecy and Gynodioecy, Charlesworth B. & Charlesworth D., 1978, The American Naturalist, p. 975, The University of Chicago Press journals
  14. 1 2 Recent Advances in the Study of Gynodioecy: the interface of theory and empiricism, Bailey M. & McCauley D.E., 2009, Annals of Botany, 104(4), p, 611-620
  15. ↑ Effects of male sterility on reproductive traits in gunodioecious plants: a meta-analysis, Shykoff J.A., Kolokotronis S.O., Collin C.L. & Lopez-Villavicencio M., 2003, Oecologia, 135(1), p. 1-9
  16. ↑ Pollen-Stigma interference in two Gynodioecious Species of Lamiaceae with Intermediate Individuals, Rodriguez-Riano T. & Amots D., 2007, Annals of Botany, 100(2), p. 423-431
  17. ↑ "Teucrium racemosum". FloraBase. Western Australian Government Department of Biodiversity, Conservation and Attractions.
  18. ↑ "Species profile - Teucrium racemosum". Queensland Government Department of Environment and Science. Retrieved 22 May 2021.
  19. ↑ "Teucrium racemosum". Northern Territory Government. Retrieved 22 May 2021.
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