Patersonia

Patersonia (or Purple flag) is a genus of the Iridaceae with about 20 species in Australia and several in the Malesian region. The genus name is a tribute to the first Lieutenant Governor of New South Wales in Australia, William Paterson.^[1]

They are perennials with basal leaves growing from a woody rhizome that in some species extends above ground to form a short trunk. The leaves are tough and fibrous with various adaptations to conserve moisture: stomata sunk in grooves, thickened cross-section, marginal hairs or thickened margins.

The flowers appear from between a pair of bracts on a leafless stem. They have three large outer tepals that are usually blue to violet, and three tiny inner tepals. There are three stamens fused at the base to form a tube around the longer style which bears a flattened stigma.

Several Patersonia species are grown as garden subjects. They can be propagated by seed or by division.

• Patersonia fragilis comes from sandy coastal heathlands in south-eastern Australia; it has narrow grey-green leaves and pale violet flowers close to the ground.

• Patersonia glabrata forms a shrub to 80 cm high with wiry tangled stems.

• Patersonia occidentalis (native iris) to 75 cm tall with blue flowers, widespread in southern Australia.

• Patersonia sericea is similar but has bracts covered in short silky hairs. It is an east coast species, replaced by the closely related P. rudis and P. lanata in Western Australia and P. macrantha in the Northern Territory.

• Patersonia umbrosa from Western Australia has two colour variants, the typical blue-violet variety, and the yellow-flowered var. xanthina from the karri forests.

References

Cooke, D.A. (1986) Patersonia. Flora of Australia 46: 13-26. (Australian Government Publishing Service: Canberra).