''Pimelea serpyllifolia'', commonly known as thyme riceflower, 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 to southern Australia. It is an erect shrub with narrowly elliptic to spatula-shaped leaves, and compact heads of 4 to 12 yellow, yellowish-green or white flowers surrounded by 2 or 4 leaf-like involucral bracts. Male and female flowers are borne on separate plants.

Description

''Pimelea serpyllifolia'' is an erect shrub that typically grows to a height of , but is rarely stunted or prostrate in exposed positions. The leaves are borne in opposite pairs on

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 ...

stems and are crowded, narrowly elliptic to spatula-shaped, long and wide. The leaves are glabrous, and the same shade of green on both sides. The flowers are borne in compact heads of 4 to 12 yellow, yellowish-green or white flowers surrounded by 2 or 4

sessile Sessility, or sessile, may refer to: * Sessility (motility), organisms which are not able to move about * Sessility (botany), flowers or leaves that grow directly from the stem or peduncle of a plant * Sessility (medicine), tumors and polyps that ...

, elliptic involucral bracts long and wide, female and male flowers borne on separate plants. The

floral tube In angiosperms, a hypanthium or floral cup is a structure where basal portions of the Sepal, calyx, the petal, corolla, and the stamens form a cup-shaped tube. It is sometimes called a floral tube, a term that is also used for corolla tube and cal ...

of female plants is long, the

sepal A sepal () is a part of the flower of angiosperms (flowering plants). Usually green, sepals typically function as protection for the flower in bud, and often as support for the petals when in bloom., p. 106 The term ''sepalum'' was coined b ...

s long, and of male plants and long respectively.

Taxonomy

''Pimelea serpyllifolia'' was first formally described in 1810 by Robert Brown in his ''

Prodromus Florae Novae Hollandiae et Insulae Van Diemen ''Prodromus Florae Novae Hollandiae et Insulae Van Diemen'' (Prodromus of the Flora of New Holland and Van Diemen's Land) is a flora of Australia written by botanist Robert Brown and published in 1810. Often referred to as ''Prodromus Flora Novae ...

''. The specific epithet, ''serpyllifolia'' means "wild

thyme Thyme () is the herb (dried aerial parts) of some members of the genus ''Thymus'' of aromatic perennial evergreen herbs in the mint family Lamiaceae. Thymes are relatives of the oregano genus ''Origanum'', with both plants being mostly indigenou ...

-leaved". In 1988,

Barbara Lynette Rye Barbara Lynette Rye is an Australian botanist born in 1952. Barbara Rye has been associated with the Western Australian Herbarium, where her work as a taxonomist has been the source of many new descriptions of plants. The number of taxa recorded ...

named two subspecies of ''P. serpyllifolia'' in the journal ''

Nuytsia ''Nuytsia floribunda'' is a hemiparasitic tree found in Western Australia. The species is known locally as moodjar and, more recently, the Christmas tree or Western Australian Christmas tree. The display of intensely bright flowers during the ...

'', and the names are accepted by the

Australian Plant Census The Australian Plant Census (APC) provides an online interface to currently accepted, published, scientific names of the vascular flora of Australia, as one of the output interfaces of the national government Integrated Biodiversity Information Syst ...

'': * ''Pimelea serpyllifolia'' subsp. ''occidentalis'' Rye differs from the

autonym Autonym may refer to: * Autonym, the name used by a person to refer to themselves or their language; see Exonym and endonym * Autonym (botany), an automatically created infrageneric or infraspecific name See also * Nominotypical subspecies, in zo ...

in having stems that are hairy below the flower heads, and flowers that are at least sparsely hairy inside. * ''Pimelea serpyllifolia'' Rye subsp. ''serpyllifolia'' has glabrous stems and flowers that are usually glabrous inside.

Distribution and habitat

Subspecies ''serpyllifolia'' grows in shrubland and woodland mostly in near-coastal areas of Victoria and South Australia, but also in the far north-west of Victoria. There are also small populations near Euston in far south-western New South Wales, near Eucla in Western Australia, and in a few places in north-eastern Tasmania and on

Bass Strait Islands Bass Strait () is a strait separating the island state of Tasmania from the Australian mainland (more specifically the coast of Victoria, with the exception of the land border across Boundary Islet). The strait provides the most direct waterway ...

. Subspecies ''occidentalis'' grows in near-coastal areas between

Israelite Bay Israelite Bay is a bay and locality on the south coast of Western Australia. Situated in the Shire of Esperance local government area, it lies east of Esperance and the Cape Arid National Park, within the Nuytsland Nature Reserve and the Grea ...

and

Twilight Cove Twilight Cove is situated at the end of the Baxter Cliffs on the south coast of Western Australia on the Great Australian Bight coastline. It has had other names, including ''Malbinya''. The local Aboriginal language for the area (known as Willi ...

in southern Western Australia.

Conservation status

''Pimelea serpyllifolia'' subsp. ''serpyllifolia'' is listed as "endangered" in New South Wales under the New South Wales Government '' Biodiversity Conservation Act 2016''.

References

{{Taxonbar, from1=Q51047161, from2=Q51057277, from3=Q51057294 serphyllifolia Malvales of Australia Flora of New South Wales Flora of South Australia Flora of Victoria (state) Flora of Western Australia Plants described in 1810 Taxa named by Robert Brown (botanist, born 1773) Dioecious plants