| I became interested in Proteaceae via gravelly soils while working for the WA Department of Agriculture as an adviser. At that time it was thought that ancient fluctuating groundwater created gravel, and that Proteaceae evolved to grow on these soils. Dr Bill Verboom (a work colleague), turned this idea on its head by proposing that plants can create soils to give them an evolutionary advantage. Proteaceae have evolved cluster roots, which enable them to access the nutrient phosphorus in infertile soils. Cluster roots and associated soil microbes create lateritic soils including bauxite. For more information click here. |  Australia girt by gravel |
I recently realised that I didn't know how to distinguish Proteaceae genera from each other. Alas my ageing memory is less than photographic, and I rely on rules of thumb. Here is my rough guide. No doubt there are exceptions but some may find it useful.
Proteaceae features
| Proteaceae have tubular flowers (a corolla) consisting of four tepals (combined petal/sepal), which are mostly joined into a tube. The central female part consists of a superior (above surface of flower base) ovary connected to a single unbranched style. Their fruit only has one or two seeds in a 2-lobed papery (Grevillea) or woody (Hakea, Lambertia) fruit or cone (Banksia, Isopogon or Petrophile, or tiny nuts (Conospermum, Synaphea, or drupes (Persoonia). Most Proteaceae produce few seeds, particularly resprouters |
Species with short corolla tube and small tepals
 Synaphea has divided leaves and clusters of yellow flowers |  Conospermum has entire leaves and clusters of tiny blue grey or white flowers |  Conospermum stoechadis common smokebush |
Species with a medium to long corolla tube - the style bursts out of the side of the tube before the tepals separate
 section of a grevillea flower spike |  Grevilleas mostly have flowers with thickened styles on end of branches and papery fruit. |
 Adenanthos (woolly bushes) have only 1 or 2 flowers together. |  Hakeas mostly have thickened styles on flowers between leaves on branches and woody fruit |
 Dryandras ​mostly have thin styles and groups of flowers surrounded by bracts (modified leaves) |  Banksias mostly have thin styles and flowers and fruit in a round or elongate cone |
Species with medium to long corolla tube - style emerges from end of corolla tube as tepals fold back
 Stirlingia. Anthers inside folded tepal. Entire leaves and sprays of flowers arise from plant base. |  Persoonia. Anthers around style. Entire leaves. |
 Petrophile. Anthers inside folded tepal. Scaly cone fruit. |  Isopogon. Anthers inside folded tepal. Smooth cone fruit. |
Lambertia. Anthers inside folded tepal ends of the corolla tube. Woody fruit with horned lobes.