About hooks, hairy legs, and sedges

About hooks, hairy legs, and sedges

Tramping in New Zealand forests can be an enjoyable and very relaxing activity. However, if your legs are hairy, it could be a painful and very annoying experience. Camouflaged among ferns and ground orchids, hook grasses are waiting, ready to clasp to the hairs or clothing of any unwary tramper.

Hook grasses get their name from a hook-like structure which arises from the base of the ovary of each female flower.

Detail of a receptive female flower of Uncinia zotovii indicating hook and stigmas. Photo by C.A. Lehnebach (c) Museum of New Zealand Te Papa Tongarewa.

This structure allows dispersal of the achene, a single seed produced by each female flower, to other sites by clasping to the hairs, or feathers, of any animal (or hairy tramper) passing by.

Seed (achene) of a native hook sedge. Photo by C.A. Lehnebach (c) Museum of New Zealand Te Papa Tongarewa.

Flowers in Uncinia are unisexual, that is male and female reproductive structures are on separate flowers. In Uncinia, female flowers are at the base of the spike while male flowers are at the top.

Mature spike of Uncinia caespitosa indicating female and male sections. Photo by C.A. Lehnebach (c) Museum of New Zealand Te Papa Tongarewa.

Only female flowers have a hook. Male flowers are small and have three stamens, which quickly fall off after the pollen is released.

Male flowers of Uncinia and detail of stamens. Photo by C.A. Lehnebach (c) Museum of New Zealand Te Papa Tongarewa.

New Zealand is the diversity hotspot for Uncinia, however, little is known about their ecology and the actual number of species is still uncertain. Some species are so variable that it is possible they may consist of two or more species.

As part of my work in Te Papa I have investigated a group of morphologically variable Uncinia. The main goals of my study were to understand the cause(s) of this variability and to produce revised descriptions for these species to make their identification easier.


  1. Recently while checking a trap line on the Arcus Dam walk (Otaki Gorge) I came across a waxeye hopelessly entangled by a head of hookgrass. Would have been fair game to the first rat or stoat to come along if it didn’t give up and die first. Lost a lot of feathers from one wing but flew away steadily after I released it

  2. This is the important publish! Thanks for it! Using sincerely Luke aka couchgool.

  3. Great photos. Really descriptive. I had some species of Uncinia latch onto me while walking in Pourakino (Southland). Naturally, I took them home and planted them. They sprouted easily. Next time I go to Pourakino, I will bring magnification to inspect male/female aspects of the flower. Thanks for the post!

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