23 July 2012

Philotheca rhomboidea – Rutaceae

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Philotheca rhomboidea – Rutaceae

Most Philotheca species were originally placed in the Eriostemon genus, but were transferred from there after a taxonomic review by Dr Paul G Wilson in 1998 (Nuytsia Vol. 12). They were separated not by anther differences as in the past, but by the number of veins on the petals, with Philotheca having only one and Eriostemon several.

Philotheca rhomboidea was known prior to 1998 as Eriostemon rhomboideus, a name now discarded. It is endemic to Western Australia and occurs in inland environments (locally on sandy loams and gravel soils), ranging from NW of Esperance to the Lake Grace region, then again NW to Coorow, to return via a southeasterly arc to NNW of Esperance.

This species grows to around a metre (3’) in height, but is usually smaller: the thick strongly glandular leaves are between 2-4 mm (around 1/8”) in length and are rhomboidal to obovoid in shape (hence its species name).

The long flowering flowers (over 1 cm or 1/2” diameter) when in bud are pink, but open to white or pale pink and being much larger than the foliage are quite showy in full bloom. With early rainfall flowering can begin in autumn, but is more common and prolific from July to November.

Philotheca belongs to the Rutaceae family.