''Hypocalymma tetrapterum'', commonly known as papillose 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 shrub, with narrowly egg-shaped leaves with the narrower end towards the base, and white yellow flowers with 20 to 35

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 ...

s in several rows.

Description

''Hypocalymma tetrapterum'' is a spreading to erect shrub that typically grows to a height of . Its leaves are narrowly egg-shaped with the narrower end towards the base or narrowly oblong, long, wide and

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 ...

or on a

petiole Petiole may refer to: *Petiole (botany), the stalk of a leaf, attaching the blade to the stem *Petiole (insect anatomy) In entomology, petiole is the technical term for the narrow waist of some hymenopteran insects, especially ants, bees, and ...

up to long. The lower side of the leaves is convex with many 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 ...

, surrounded by a circle of small blisters. 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 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, long and there are 20 to 35 white stamens, the longest filaments long. Flowering occurs from June to October, and the fruit is a capsule long and in diameter.

Taxonomy

''Hypocalymma tetrapterum'' was first formally described in 1862 by

Nikolai Turczaninow Nikolai Stepanovich Turczaninow (; 1796 – ) was a Russian botanist and plant collector who first identified several genera and many species of plants. Education and career Born in 1796, Turczaninow attended high school in Kharkov. In 181 ...

in the ''Bulletin de la Société impériale des naturalistes de Moscou''. 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 ...

(''tetrapterum'') means 'four-winged'.

Distribution and habitat

This species of ''Hypocalymma'' grows in sand or heavier soils, often in woodland, mainly between Eneabba and Badgingarra 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 ...

and

Swan Coastal Plain The Swan Coastal Plain in Western Australia is the geographic feature which contains the Swan River as it travels west to the Indian Ocean. The coastal plain continues well beyond the boundaries of the Swan River and its tributaries, as a geol ...

bioregions of south-western Western Australia.

References

{{Taxonbar, from=Q15367991 tetrapterum Endemic flora of Western Australia Rosids of Western Australia Plants described in 1862 Taxa named by Nikolai Turczaninow