Pachystegia insignis (Marlborough rock daisy)

Kingdom: Plantae
(Unranked): Angiosperms
(Unranked): Eudicots
(Unranked): Asterids
Order: Asterales
Family: Asteraceae
Tribe: Astereae
Genus: Pachystegia
Species: P. insignis
Binomial name: Pachystegia insignis
Common name: Marlborough Rock Daisy, Kaikoura Rock Daisy, Olearia insignis, Rock tree daisy

Pachystegia insignis is a native species of flowering plants in the daisy family, Asteraceae. It is a compact, low-growing shrub up to 0.9m tall naturally occurring on steep rocky hillsides in coastal and mountain situations only in Marlborough. Pachystegia insignis is highly resistant to summer drought conditions with their thick leathery leaves, dense felt like tomentum on the undersides and on young stems help to retain water.
This rock daisy is common throughout eastern parts of Marlborough. It is most plentiful along the Kaikoura coast where it can be seen growing off many of the steep rocky bluffs or stony sites composed of sandstone gravels. The local rock types have a relatively high level of natural fertilizer especially calcium bound phosphorus (Ca. P).
Pachystegia have large dark green leathery glossy leaves 7.5–17.5 cm long which have a heavy felting of silvery, white tomentum (a covering of closely matted or fine hairs) on the upper surface when young, becoming deep green and glossy with age. The mature leaves are shiny green above and are clothed in a thick white or light brown tomentum beneath.
In June to August, the immature flower heads start as felt drumsticks and then bear daisy-like solitary white flower heads, up to 75mm across, with yellow centres. Fluffy seeds follow.

At present, 3 species are recognised in the genus. Pachystegia insignis, Pachystegia minor and Pachystegia rufa all endemic to New Zealand. Pachystegia insignis is by far the most common and widespread within the genus’s natural region which as the common name suggests is Marlborough. There it is found from the Wairau River in the north and to the south to the Waiau River in North Canterbury and inland as far as Molesworth Station. The other two species, P. rufa and P. minor are also found growing within this range but are confined too much smaller areas. It is thought that P. rufa is only found in four small gullies all in close proximity. Pachystegia insignis hybridises readily with Pachystegia rufa, creating a variety of intermediate forms.

Pachystegia insignis growing on a cliff face near Kaikoura, South Island.