Synaphea pinnata, commonly known as Helena synaphea, is a species of flowering plant in the family Proteaceae and is endemic to a small area in the south west of Western Australia. It is a low, open shrub with erect stems, more or less flat, pinnatisect leaves and spikes of openly spaced yellow flowers.
Synaphea pinnata is a low, open shrub that typically grows to a height of and has stems up to long. Its leaves are more or less flat, pinnatisect, usually with up to three lobes from each lobe, long and wide, on a petiole long. The midrib and lateral veins are prominent only on the lower surface. The flowers are yellow and openly spaced on a spike long on a branched peduncle long. The bracts are long and covered with soft hairs pressed against the surface. The perianth is more or less straight, opening widely and , the upper tepal long and wide, the lower tepal long. The stigma is round and deeply concave, about long and wide, and the ovary is covered with soft hairs. Flowering occurs from October to November, and the fruit is elliptic with a curved beak, long and hairy.
Synaphea pinnata was first formally described in 1839 by John Lindley in his A Sketch of the Vegetation of the Swan River Colony. The specific epithet (pinnata) means .
Helena synaphea is found in the Darling Scarp and the hills in the eastern suburbs of Perth between John Forrest National Park and Gosnells in the Jarrah Forest and Swan Coastal Plain bioregions of south-western Western Australia, where it grows in sandy-clay-loamy soils over laterite or granite.
Synaphea pinnata is listed as "not threatened" by the Government of Western Australia Department of Biodiversity, Conservation and Attractions