''Hypocalymma tenuatum'', commonly known as Lesueur myrtle, is a species of flowering plant in the myrtle family

Myrtaceae Myrtaceae (), the myrtle family, is a family of dicotyledonous plants placed within the order Myrtales. Myrtle, pōhutukawa, bay rum tree, clove, guava, acca (feijoa), allspice, and eucalyptus are some notable members of this group. All ...

, and is

endemic Endemism is the state of a species being found only 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 foun ...

to the a restricted area in the

south-west The points of the compass are a set of horizontal, radially arrayed compass directions (or azimuths) used in navigation and cartography. A ''compass rose'' is primarily composed of four cardinal directions—north, east, south, and west—each ...

of Western Australia. It is a low, spreading shrub, with linear leaves, and white or pale yellow flowers with 20 to 25

stamen The stamen (: stamina or stamens) is a part consisting of the male reproductive organs of a flower. Collectively, the stamens form the androecium., p. 10 Morphology and terminology A stamen typically consists of a stalk called the filament ...

Description

''Hypocalymma tenuatum'' is a low, spreading shrub that typically grows to a height of . Its leaves are linear in outline, long, wide and thick. The lower side of the leaves is deeply convex and grooved, with star-like oil

glands A gland is a Cell (biology), cell or an Organ (biology), organ in an animal's body that produces and secretes different substances that the organism needs, either into the bloodstream or into a body cavity or outer surface. A gland may also funct ...

. The flowers are in diameter, and often arranged in pairs with

bracteole In botany, a bract is a modified or specialized leaf, associated with a reproductive structure such as a flower, inflorescence axis or cone scale. Bracts are usually different from foliage leaves in size, color, shape or texture. They also look ...

s long at the base. The

floral tube In angiosperms, a hypanthium or floral cup is a structure where basal portions of the calyx, the 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 calyx tube."Lec ...

is about long and wide and 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 Etymology The term ''sepalum'' ...

s are egg-shaped, long and wide. The petals are white or pale yellow, long and there are 20 to 25 white or pale yellow stamens, the longest filaments long. Flowering mainly occurs from August to October, and the fruit is a capsule long and in diameter.

Taxonomy

''Hypocalymma tenuatum'' was first formally described in 2003 by

Arne Strid P. Arne K. Strid (born March 7, 1943, in Kristianstad, Sweden) is a Swedish botanist and expert on Greek flora. Biography He studied botany, chemistry and genetics in the Lund University, University of Lund and graduated in 1970. His doctorate w ...

and Greg Keighery in the ''Nordic Journal of Botany'' from specimens collected on

Mount Lesueur Mount Lesueur is a near-circular, flat-topped mesa located from Jurien Bay in Western Australia Western Australia (WA) is the westernmost state of Australia. It is bounded by the Indian Ocean to the north and west, the Southern Ocean to t ...

in 1980. The

specific epithet In Taxonomy (biology), taxonomy, binomial nomenclature ("two-term naming system"), also called binary nomenclature, is a formal system of naming species of living things by giving each a name composed of two parts, both of which use Latin gramm ...

(''tenuatum'') means 'completely slender', referring to the drawn-out branches.

Distribution and habitat

This species of ''Hypocalymma'' is found with laterite in

wandoo Wandoo is the common name for a number of Western Australian ''Eucalyptus'' species, all of which have smooth white bark. The original "wandoo" is ''Eucalyptus wandoo''. Additional species have been given this name because of a perceived likeness w ...

woodland or on sandstone outcrops between the

Lesueur National Park Lesueur National Park is a national park straddling the boundary between the Wheatbelt and Mid West regions of Western Australia, 211 km north of Perth. The park was gazetted in 1992. It includes two mesas known as Mount Lesueur and Moun ...

and

Warradarge Warradarge is a locality in the Mid West region of Western Australia Western Australia (WA) is the westernmost state of Australia. It is bounded by the Indian Ocean to the north and west, the Southern Ocean to the south, the Northern Territ ...

in the

Geraldton Sandplains Geraldton Sandplains is an Interim Biogeographic Regionalisation for Australia, interim Australian bioregion of Western Australia. It has an area of . The Geraldton Sandplains is part of the larger Southwest Australia savanna ecoregion, as asses ...

bioregion of south-western Western Australia.

Conservation status

''Hypocalymma tenuatum'' is listed as " Priority Two" by the Government of Western Australia

Department of Biodiversity, Conservation and Attractions The Department of Biodiversity, Conservation and Attractions (DBCA) is the Government of Western Australia, Western Australian government department responsible for managing lands and waters described in the ''Conservation and Land Management A ...

, meaning that it is poorly known and from one or a few locations.

References

{{Taxonbar, from=Q15367891 tenuatum Endemic flora of Western Australia Rosids of Western Australia Plants described in 2003 Taxa named by Gregory John Keighery Taxa named by Arne Strid