Kingdom: Plantae
Division: Pteridophyta
Class: Pteridopsida
Order: Athyriales
Family: Blechnaceae
Genus: Cranfillia 
Species: C. fluviatile
Binomial name: Cranfillia fluviatilis 
Synomon: Blechnum fluviatile, Spicanta fluviatilis, Stegania fluviatilis, Lomaria fluviatilis var. ramose, Lomaria fluviatilis, Lomaria rotundifolia, Lomaria rotundifolia,  
Common names:  Kiwakiwa, Star fern, Creek fern, kiwikiwi, 

Cranfillia fluviatilis (was named Blechnum fluviatile) is a herbaceous symmetrical fern like a starfish with a ladder like frond measuring up to 50 cm long. Growing in a distinctive ground-hugging rosette shape, its fertile fronds - dark brown and spiky - stand upright from the centre, while the drooping sterile fronds with their nearly round leaflets form the rosette.
As the parent plant ages, it develops a short trunk central to a surrounding colony. It is a hardy small common ground fern which requires moist, shaded conditions for optimal growth.
Blechnum fluviatile is native to New Zealand and southeast Australia. This fern species occurs throughout much of New Zealand's forests.

Kiwakiwa Blechnum fluviatile Kiwakiwa..JPG

Cranfillia fluviatilis with dark upright fertile fronds.
Kiwakiwa Blechnum fluviatile Kiwakiwa.JPG

Photographed at Otira Wilton Bush Reserve
Blechnum fluviatile Kiwakiwa 2 .JPG

The top side of the sterile frond.
Blechnum fluviatile Kiwakiwa.JPG

The underside of a sterile frond.
Blechnum fluviatile Kiwakiwa 1 .JPG  

Fertile frond.
Fertile frond Blechnum fluviatile-6.JPG

Sori on a fertile frond.
Fertile frond Creek fern Blechnum fluviatile-7.JPG

Thanks to Wikipedia for text and information: https://creativecommons.org/licenses/by-sa/3.0/