T.E.R:R.A.I.N - Taranaki Educational Resource: Research, Analysis and Information Network


Hierochloe redolens (karetu)

Kingdom: Plantae
(unranked): Angiosperms
(unranked): Monocots
(unranked): Commelinids
Order: Poales
Family: Poaceae
Subfamily: Pooideae
Genus: Hierochloe
Species: H. redolens
Scientific name: Hierochloe redolens
Synonyms: Holcus redolens, Avena redolens, Anthoxanthum redolens, Hierochloe antarctica var. redolens, Holcus redolens, Torresia redolens, Hierachloe banksiana.
Common names: kāretu, Scented grass, Holy grass, Scented Holy Grass

Hierochloe redolens (kāretu) is a large, robust, indigenous grass that forms loose tufts up to about 1 m tall. It is found throughout New Zealand’s North, South, Chatham and Three Kings Islands. It is also indigenous to Australia, New Guinea and South America. 
Hierochloe redolens is fast-growing and can reach over a metre in height. The dark green flat leaf blades, above the sheath, are up to 70 cm long, mostly flat apart from slightly inwardly rolled margins toward the base, and broad at 8−12 mm wide. They are dull green above and glossy green beneath. They are usually hairless and smooth above but the main veins are prominent and rough to touch on the lower surface, and the margins may be prickle-toothed. The leaf sheath, the lower part of the leaf that tightly clings to the stem, is 15−30 cm long and is often a rich purple-red colour on the lower portion.

Kāretu is threatened because it is intolerant of heavy browsing. Since the introduction of wild and domestic herbivores (sheep, cattle, rabbits and hares, deer, possums, goats) and having competition from browse-tolerant introduced grasses, there has been a marked decline in the abundance of kāretu since the arrival of Europeans.

The green leaf has a faint scent reminiscent of coconut or fresh-mown hay, this odour becomes stronger as the leaf dries. Kāretu scented leaves were used by the Maori people for weaving. To make leaf more pliable the midrib (tuaka) was taken out of each leaf before being used for plaiting into belts, headbands and bands for suspending breast ornaments. The flowering tops of kāretu and the roniu (Brachyscome radicata http://www.terrain.net.nz/friends-of-te-henui-group/new-plant-page/brachyscome-radicata-roniu.html) were wrapped in fibrous leaves and worn as a scented necklace. The sitting and sleeping areas in the wharepuni (whare) were strewn with leaves of kāretu. It was also used in the preparation of scented oils.
Maori children used the culm (hollow stem) of kāretu in game called topa (koke or niu). To read about this game visit: http://nzetc.victoria.ac.nz/tm/scholarly/tei-BesGame-t1-body-d6-d1-d17.html





Photo showing the green leaf blade with its parallel veins and the ligule. The ligule is outgrowth where the leaf blade and sheath join. It stops water entering between the two.


The purple leaf sheath.
 

The seed heads