''Pimelea trichostachya'', commonly known as annual riceflower, spiked riceflower or flax weed, is a species of flowering plant in the family

Thymelaeaceae The Thymelaeaceae are a cosmopolitan family of flowering plants composed of 50 genera (listed below) and 898 species.Zachary S. Rogers (2009 onwards)A World Checklist of Thymelaeaceae (version 1) Missouri Botanical Garden Website, St. Louis. It ...

and is

endemic Endemism is the state of a species being found in a single defined geographic location, such as an island, state, nation, country or other defined zone; organisms that are indigenous to a place are not endemic to it if they are also found elsew ...

to continental Australia. It is a slender, semi-woody,

annual Annual may refer to: * Annual publication, periodical publications appearing regularly once per year **Yearbook ** Literary annual * Annual plant * Annual report * Annual giving * Annual, Morocco, a settlement in northeastern Morocco * Annuals (b ...

shrub with narrowly elliptic or linear leaves and densely hairy, white or yellow flowers and green, purple-tinged fruit. It is toxic to livestock.

Description

''Pimelea trichostachya'' is a slender, erect, sem-woody annual shrub that typically grows to a height of up to and has hairy stems. The leaves are arranged alternately and are narrowly elliptic or linear, long and wide. The leaves are

glabrous Glabrousness (from the Latin ''glaber'' meaning "bald", "hairless", "shaved", "smooth") is the technical term for a lack of hair, down, setae, trichomes or other such covering. A glabrous surface may be a natural characteristic of all or part of ...

or sparsely hairy. The flowers are arranged in head-like spikes about long and wide, on the ends of branchlets on a peduncle up to long, each flower on a hairy

pedicel Pedicle or pedicel may refer to: Human anatomy *Pedicle of vertebral arch, the segment between the transverse process and the vertebral body, and is often used as a radiographic marker and entry point in vertebroplasty and kyphoplasty procedures ...

. The flowers are

bisexual Bisexuality is a romantic or sexual attraction or behavior toward both males and females, or to more than one gender. It may also be defined to include romantic or sexual attraction to people regardless of their sex or gender identity, whi ...

, white or yellow and densely covered with long, spreading hairs. Flowering occurs in most months with a peak from August to December and the fruit is green with a purplish tinge and about long.

Taxonomy

''Pimelea trichostachya'' was first formally described in 1848 by

John Lindley John Lindley FRS (5 February 1799 – 1 November 1865) was an English botanist, gardener and orchidologist. Early years Born in Catton, near Norwich, England, John Lindley was one of four children of George and Mary Lindley. George Lindley w ...

in Thomas Mitchell's ''Journal of an Expedition into the Interior of Tropical Australia''. The

specific epithet In taxonomy, binomial nomenclature ("two-term naming system"), also called nomenclature ("two-name naming system") or binary nomenclature, is a formal system of naming species of living things by giving each a name composed of two parts, bot ...

(''trichostachya'') means "hairy flower-spike".

Distribution

Annual rice-flower mainly grows in deep sand im mallee and occurs in all mainland states and the

Northern Territory The Northern Territory (commonly abbreviated as NT; formally the Northern Territory of Australia) is an states and territories of Australia, Australian territory in the central and central northern regions of Australia. The Northern Territory ...

, but is absent from most of the north of the country, from the east and west coasts and from most of

Victoria Victoria most commonly refers to: * Victoria (Australia), a state of the Commonwealth of Australia * Victoria, British Columbia, provincial capital of British Columbia, Canada * Victoria (mythology), Roman goddess of Victory * Victoria, Seychelle ...

Effect on livestock

''Pimelea trichostachya'', along with '' P. simplex'' and '' P. elongata'', is toxic to stock. The first cases of "St George disease" were reported in Queensland in 1921, but it was not until 1960 that pimelea poisoning was identified as the cause. Symptoms of poisoning in cattle include fluid swellings, mostly under the jaw, diarrhoea and weight loss. Horses and sheep are also susceptible.

References

{{Taxonbar, from=Q17582265 trichostachya Malvales of Australia Flora of New South Wales Flora of Victoria (state) Flora of Western Australia Flora of South Australia Flora of Queensland Flora of the Northern Territory Plants described in 1848 Taxa named by John Lindley