''Boronia megastigma'', commonly known as brown boronia, sweet-scented boronia or scented boronia, is a plant in the citrus

family Family (from ) is a Social group, group of people related either by consanguinity (by recognized birth) or Affinity (law), affinity (by marriage or other relationship). It forms the basis for social order. Ideally, families offer predictabili ...

Rutaceae The Rutaceae () is a family (biology), family, commonly known as the rueRUTACEAE
in Bo ...

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

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 ...

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 Territory to the north-east, and South Australia to the south-east. Western Aust ...

. It is a slender, erect shrub with aromatic leaves and flowers, the leaves with three or five leaflets and the flowers cup-shaped, dark brown to purplish black on the outside and yellow inside.

Description

''Boronia megastigma'' is a shrub that typically grows to a height of and has slender branches covered with fine, soft hairs. The leaves are

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 ...

with three or five thick, slender, linear leaflets long and strongly aromatic. The flowers are borne singly in leaf

axil A leaf (: leaves) is a principal appendage of the stem of a vascular plant, usually borne laterally above ground and specialized for photosynthesis. Leaves are collectively called foliage, as in "autumn foliage", while the leaves, stem, fl ...

s on a

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 ...

about long, the flowers cup-shaped, hanging, aromatic and sometimes in large numbers along a flowering branch. The four

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 very broadly egg-shaped,

glabrous Glabrousness () 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 a plant or animal, or be due to loss because of a physical condition, ...

and about long. The four

petal Petals are modified leaves that form an inner whorl surrounding the reproductive parts of flowers. They are often brightly coloured or unusually shaped to attract pollinators. All of the petals of a flower are collectively known as the ''corol ...

s are more or less round, long, reddish brown to dark brown or purplish black on the outside and yellow inside. Sometimes the petals are also yellow on the outside. There are eight

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 with those near the sepals having a more or less round, dark purple

anther 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 ...

about long and

sterile Sterile or sterility may refer to: *Asepsis, a state of being free from biological contaminants * Sterile (archaeology), a sediment deposit which contains no evidence of human activity *Sterilization (microbiology), any process that eliminates or ...

. The stamens near the petals have a similar anther but pale yellow and

fertile Fertility in colloquial terms refers the ability to have offspring. In demographic contexts, fertility refers to the actual production of offspring, rather than the physical capability to reproduce, which is termed fecundity. The fertility rate is ...

. The stigma is unusually large, dark purple or black with four lobes.

Taxonomy and naming

''Boronia megastigma'' was first formally described in 1848 by

Friedrich Gottlieb Bartling Friedrich Gottlieb Bartling (December 9, 1798 – November 20, 1875) was a German botanist who was a native of Hanover. He studied natural sciences at the University of Göttingen, and in 1818 took a botanical journey through Hungary and Croatia ...

and the description was published in Lehmann's book ''Plantae Preissianae''. 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 ...

(''megastigma'') is derived from the

Ancient Greek Ancient Greek (, ; ) includes the forms of the Greek language used in ancient Greece and the classical antiquity, ancient world from around 1500 BC to 300 BC. It is often roughly divided into the following periods: Mycenaean Greek (), Greek ...

words ''mega'' meaning "large" or "great" and ''stigma'', referring to the large stigma of this boronia.

Distribution and habitat

Brown boronia grows in winter-wet swamps and woodland, mainly in the

karri ''Eucalyptus diversicolor'', commonly known as karri, is a species of flowering plant in the family Myrtaceae and is Endemism, endemic to the Southwest Australia, south-west of Western Australia. It is a tall tree with smooth light grey to cre ...

forests and the southern edges of the

jarrah ''Eucalyptus marginata'', commonly known as jarrah, in Noongar language and historically as Swan River mahogany, is a plant in the myrtle family, Myrtaceae and is endemic to the south-west of Western Australia. It is a tree with rough, fibro ...

forests between Harvey and

Cape Riche Cape Riche is a cape in the Great Southern region of Western Australia. By road, it is south-east of Perth and north-east of Albany. It is part of the locality of Wellstead and is south of the townsite. Facilities in the area include a bo ...

Use in horticulture

This is one of several species of ''

Boronia ''Boronia'' is a genus of about 160 species of flowering plants in the citrus family Rutaceae. Most are endemic to Australia with a few species in New Caledonia, which were previously placed in the genus ''Boronella''. They occur in all Australi ...

'' cultivated for its intense, attractive scent. It is the main ''Boronia'' source of

essential oil An essential oil is a concentrated hydrophobic liquid containing volatile (easily evaporated at normal temperatures) chemical compounds from plants. Essential oils are also known as volatile oils, ethereal oils, aetheroleum, or simply as the ...

s, while its relative '' Boronia heterophylla'' is more often harvested for use as an aromatic cut ornamental. All of the organs of the flower contain oil glands and their activity is greatest while the stigma is receptive to

pollen Pollen is a powdery substance produced by most types of flowers of seed plants for the purpose of sexual reproduction. It consists of pollen grains (highly reduced Gametophyte#Heterospory, microgametophytes), which produce male gametes (sperm ...

, which suggests that production of scent may serve to attract pollinators such as insects. There are several cultivated varieties which bear flowers of different colors. The two main

aroma compound An aroma compound, also known as an odorant, aroma, fragrance, flavoring or flavor, is a chemical compound that has a smell or odor. For an individual chemical or class of chemical compounds to impart a smell or fragrance, it must be sufficien ...

s of the oil of this species are

β-ionone The ionones, from greek ἴον ion "violet", are a series of closely related chemical substances that are part of a group of compounds known as rose ketones, which also includes damascones and damascenones. Ionones are aroma compounds found ...

and dodecyl acetate. The oil is used in perfumes and as a food additive that enhances fruit flavors. Over-exploitation in natural habitat areas of Southwest Western Australia has caused re-examination of over cropping in the wildflower industry. Plantations and cultivation have occurred in numbers of places outside of the natural habitat.

References

External links

Association for Societies for Growing Australian Plants
* * * {{Taxonbar, from=Q1134633 megastigma Rosids of Western Australia Crops originating from Australia Plants described in 1848 Taxa named by Friedrich Gottlieb Bartling