Bertya dimerostigma

Bertya dimerostigma
Isotype in the Australian National Herbarium
Scientific classification
Kingdom:	Plantae
Clade:	Tracheophytes
Clade:	Angiosperms
Clade:	Eudicots
Clade:	Rosids
Order:	Malpighiales
Family:	Euphorbiaceae
Genus:	Bertya
Species:	B. dimerostigma
Binomial name
Bertya dimerostigma F.Muell. [1]
Occurrence data from the Australasian Virtual Herbarium (22 June 2019)
Synonyms [1]
Bertya dimerostigma var. genuina Grüning

Bertya dimerostigma is a species of flowering plant in the family Euphorbiaceae and is endemic to inland southern Western Australia. It is an erect shrub with strap-like or narrowly oblong leaves, flowers borne singly in leaf axils, and oval capsules with a mottled, light brown seed.

Description

Bertya dimerostigma is a monoecious or sometimes dioecious shrub that typically grows to a height of up to 2 m (6 ft 7 in) and has many glabrous, mostly sticky branches. Its leaves are strap-like or narrowly oblong, 6–10 mm (0.24–0.39 in) long and 0.9–1.4 mm (0.035–0.055 in) wide and sessile or on a short petiole. The upper surface of the leaves is green and glabrous, the lower surface white and densely covered with star-shaped hairs. The flowers are borne singly in leaf axils on a peduncle 0.5–2 mm (0.020–0.079 in) long. There are five or six oblong or narrowly egg-shaped bracts 1–4 mm (0.039–0.157 in) long and 0.5–0.9 mm (0.020–0.035 in) wide. Male flowers are sessile with five red egg-shaped or elliptic sepal lobes 2.8–5.1 mm (0.11–0.20 in) long and 2.2–2.7 mm (0.087–0.106 in) wide and have about 18 to 46 stamens. Female flowers are sessile, the five sepal lobes egg-shaped to broadly egg-shaped, 1.5–3.5 mm (0.059–0.138 in) long and 1.5–1.8 mm (0.059–0.071 in) wide. Female flowers usually have no petals, the ovary elliptic, and glabrous, the style about 0.2 mm (0.0079 in) long with three spreading yellowish-green limbs 1.1–1.5 mm (0.043–0.059 in) long, each with two to four lobes 0.9–1.1 mm (0.035–0.043 in) long. Flowering has been recorded mostly between June and November, and the fruit is an oval capsule 6–7 mm (0.24–0.28 in) long and 3.2–3.5 mm (0.13–0.14 in) wide with a single elliptic or oblong, light brown seed mottled with dark brown, 3.0–4.5 mm (0.12–0.18 in) long and 2.3–2.4 mm (0.091–0.094 in) wide with a yellowish-white caruncle. ^{[2] [3]}

Taxonomy

Bertya dimerostigma was first formally described in 1882 by Ferdinand von Mueller in his Southern Science Record from specimens collected near Victoria Spring by Ernest Giles. ^{[4] [5]} The specific epithet (dimerostigma) means 'double stigma'. ^[6]

Distribution and habitat

This species of Bertya occurs in the south-west of Western Australia between Merredin, {{Hyden, Western Australia|Hyden]] and Zanthus and is found in hummock grasslands, in mallee with a tall shrub understorey, and open woodland, growing on sands often overlaying clays. ^{[2] [3] [7]}

References

1. "Bertya dimerostigma". Plants of the World Online. Retrieved 11 March 2025.
2. Halford, David A.; Henderson, Rodney John Francis (2002). "Studies in Euphorbiaceae A.L.Juss. sens. lat. 3. A revision of Bertya Planch. (Ricinocarpeae Mull.Arg., Bertyinae Mull.Arg.)". Austrobaileya. 6 (2): 199–200. Retrieved 19 February 2025.
3. Halford, David A. Moon, Chris; Orchard, Anthony E. (eds.). "Bertya dimerostigma". Flora of Australia. Australian Biological Resources Study, Department of Climate Change, Energy, the Environment and Water: Canberra. Retrieved 11 March 2025.
4. "Bertya dimerostigma". Australian Plant Name Index. Retrieved 11 March 2025.
5. von Mueller, Ferdinand (1882). "Definitions of some new Australian plants". Southern Science Record. 2 (5): 98. Retrieved 11 March 2025.
6. George, Alex; Sharr, Francis (2021). Western Australian Plant Names and Their Meanings (3rd ed.). Kardinya, WA: Four Gables Press. p. 183. ISBN   9780958034180.
7. "Bertya dimerostigma". FloraBase . Western Australian Government Department of Biodiversity, Conservation and Attractions.