As a boy I remember  itinerent flower sellers coming to our house with bunches of heavenly smelling Boronia metastigma. I recently learnt that the intense aroma is a strategy to attract  a particular pollinator - a heliozelid moth. The moth pollinates the flower while laying eggs on the carpels (ovaries). Caterpillars eat some but not all ovaries, so win win for plant and moth.
Boronias are in the Rutaceae family, which is characterised by open flowers with a superior ovary and leaves containing oil glands.Our domesticated citrus plants are in this family.
Boronias have opposite leaves and  four sepals and petals.
Recently Boronias have been split into two genera:- Boronia and Cyanothamnus. There is almost no physical difference between the genera. Two different genetic groups have evolved very similar plant features. A trifle perplexing for the amateur, but such is modern taxonomy.

When I moved to Narrogin, I was amused to find tiny Cyanothamnus ramosus flowers in Foxes Lair. Local Boronia / Cyanothamnus species are mainly pink/ white or pale blue colours with little scent. Unlike us, Insects see untraviolet light and these colours are exceptionally bright for them. Several native bee species pollinate these boronias. 
Male and female parts are clustered together in a tight group. Images of Cyanothamnus ramosus below show that a barrier of serrated stamen filaments with coarse hairs prevent insects from accessing nectar from the side. My guess is that these stop ants and other nectar thieves. To get nectar, insect pollinators have to poke their tongue down the top of the flower past the clustered anthers and stigma. To avoid self pollination, the stigma only becomes receptive after the flower's pollen has died.

The dissection of Boronia capitata subsp. capitata shows dense stamen hairs, which exclude nectar thieves.

There are several mostly pink or white coloured Boronia /Cyanothamnus species in this district. 

Two other genera in this district differ from boronias by having alternate leaves and five sepals / petals.
They look very similar.
Asterolasia pallida (white) and squamaligera (yellow) have a tiny or no sepals and petals with a hairy exterior.
Phebalium tubercolosum (white) and filifolium (yellow) are showy shrubs commonly found in mallee woodland in the east of the district. Phebalium sepals are smaller than petals, and the petals have a scaly or scurfy exterior.

Birdwhistle Rock is a historic site, which was a notable picnic, bird watching and wildflower spot. Noongars, shepherds, and sandalwood cutters, used the rock as a stopping place from Murramucking Well on the track to Harrismith, or to Wayluring Spring and on to Dongolocking. There was water from a spring coming from the side of the rock, which abruptly stopped after the 1968 earthquake, and a walled well that was buried by silt. A line of Noongar gnamma holes is on top of the rock.
​There are no facilities. An intense fire devastated the reserve in February 2022. Images below show aerial images before and after the fire.

​One can drive (about 31kms from Narrogin, with 12km of gravel road) via Yilliminning Rock, or Boundain North Road past The old Yilliminning townsite and reserve.

Unlike the Yilliminning Rock inselberg, the Birdwhistle granite outcrop has extensive geological fractures and an east - west trending dolerite dyke on the southern side.  As a result there was patchy vegetation cover over much of the rock , which was full of dead trees and weeds from decades without any fire. A bomb waiting to go off.
The 2022 wildfire was so intense that it split rocks and caused the equivalent of thousands of years of rock 'weathering' in a single event.
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​The rock is roughly an inverted U shape, with a central valley flowing south.
On the western side of the car park is a 40 ha triangle of grass tree kwongan, which is private property.

​Some good news about the fire is that it was so intense that most wild oat seeds were incinerated, which gave native plant species a chance to reestablish. The bad news is bird and animal destruction, although they will gradually recolonise from the adjoining unburnt section of Birdwhistle Nature Reserve.
There was little plant cover in 2022 apart from some fire colonising species, moss, limited tree / shrub regrowth, and some orchids. Caladenia flava, Caladenia integra, and lots of Pyrorchis nigricans.

By mid April 2023 there has been prolific regrowth of wandoos, which are over a metre in height / diameter and prolific seedling growth of acacias, Kennedyia prostrata, rock sheoak and other species. A funky post fire coloniser Gyrostemon subnudis and Stypandra glauca / Lamb Poison native lily are particulary prolific.There will be a mass of blue Lamb Poison flowers this spring, and it will be interesting to see how many orchids flower this year.

with each succeeding year new plant species will become promininent until a balance is reached in about a decade. This blog shows images of the regrowth at a number of sites.