Boronia capitata

Boronia capitata, commonly known as the cluster boronia,^[2] is a plant in the citrus family, Rutaceae and is endemic to the south-west of Western Australia. It is a slender, spreading shrub with simple leaves and pink, four-petalled flowers.

habit

Cluster boronia
Boronia capitata near Quairading
Scientific classification
Kingdom:	Plantae
Clade:	Tracheophytes
Clade:	Angiosperms
Clade:	Eudicots
Clade:	Rosids
Order:	Sapindales
Family:	Rutaceae
Genus:	Boronia
Species:	B. capitata
Binomial name
Boronia capitata Benth.[1]
Occurrence data from Australasian Virtual Herbarium

Description

Boronia capitata is a slender, spreading shrub that grows to a height of 15–130 cm (6–50 in). It has simple, thick, linear to club-shaped leaves 4–15 mm (0.2–0.6 in) long. The flowers are pink and are arranged in clusters on the ends of the branches, each on a pedicel 1–3 mm (0.04–0.1 in) long. The four sepals are broadly elliptic to narrow triangular, and the four petals are broadly elliptic, about 6 mm (0.2 in) long.^[2][3][4][5]

Taxonomy and naming

Boronia capitata was first formally described in 1863 by George Bentham and the description was published in Flora Australiensis from a specimen collected by James Drummond.^[4][6] The specific epithet (capitata) is a Latin word meaning "having a head".^[7]

In 1971, Paul G. Wilson described three subspecies:^[8]

• Boronia capitata subsp. capitata has leaves and sepals that are glabrous or fringed with hairs and flowers from September to October;^[9]
• Boronia capitata subsp. clavata has thick leaves covered with long, soft hairs, and broadly elliptic sepals fringed with hairs and flowers from April to October;^[10]
• Boronia capitata subsp. gracilis slender leaves covered with long, soft hairs and narrow egg-shaped sepals with a hairy fringe and flowers from June to November.^[11]

Distribution and habitat

• Subspecies capitata is only currently known from sandplain habitat near Pingelly;^[9][12]
• Subspecies clavata grows in heath between Corrigin, Hyden and Kojonup;^[10][13]
• Subspecies gracilis grows in winter-wet swamps between Yarloop and Margaret River.^[11][14]

Conservation

Subspecies clavata is classified as "not threatened"^[13] but subspecies gracilis is classified as "Priority Three" by the Government of Western Australia Department of Parks and Wildlife^[14] meaning that it is poorly known and known from only a few locations but is not under imminent threat.^[15] Subspecies capitata is listed as "endangered" under the Australian Government Environment Protection and Biodiversity Conservation Act 1999^[16] and as "Threatened Flora (Declared Rare Flora — Extant)" by the Department of Environment and Conservation (Western Australia).^[12] The main threats to this subspecies are clearing and fragmentation of its habitat.^[16]