In The Hills In The Hills 2016-03

Asplenium bulbiferum < Species index > Asplenium flaccidum

This article was first published in the Tararua Tramper Volume 88, no 2, March 2016

March in the hills with Barbara Mitcalfe and Chris Horne

Asplenium flabellifolium, with inset showing fertile segments. Photo: Jeremy Rolfe

Asplenium flabellifolium(approve sites), necklace fern/walking fern/butterfly fern

We have not yet found a Māori name for this month's Asplenium species, necklace fern, a dainty, distinctive fern of dry, rocky sites. Its botanical name is derived from the Latin word: flabella, a fan, and folia, a leaf.

But ferns don't have true leaves, Instead, fern fronds have segments which look like leaves but have two functions – (1) the upper surface of the segments converts visible light into energy, and (2) if you turn a segment over, you will see that the underside has sori, containing spores, which are reproductive organs, as we described for Asplenium bulbiferum.

Once recognised, this uncommon little fern is easily remembered, because it is so unusual.

Form and habit

Its narrow, delicate fronds, (4–30 cm x 0.8–4 cm) are often prostrate, but frequently arch up and over (see image).

Spaced out along the lower length of the fronds, are pale green, fan-shaped, toothed segments, paired alternately. About 2 cm x 2 cm they resemble butterfly wings, (see image), hence the origin of one of the common names.

The upper part of the fronds usually consists of the completely bare main stem called the rachis. This can extend like a slim wand, well beyond the segments, in fact, it frequently doubles its length. Arching over to touch the ground, the proliferous tip of the rachis often takes root. This produces a new necklace fern plant, hence the name, “walking fern”.

Reproduction

In the December 2015 articel, we described Asplenium bulbiferum, which has two methods of reproduction, and so does Asplenium flabellifolium. One of its methods is non-sexual, i.e., simply using the proliferating stem-tip as a 'planting tool', as you have just learnt. The other method is sexual, i.e., via the spores in the sori, on the undersides of the fan-shaped segments. (see inset).

When the mature necklace fern-spores fall to the ground, in moist conditions they develop into prothalli, then they undergo the complete fern life-cycle – see our article in the December Tramper.

Distribution

Found throughout in both North and South islands, as well as in Australia, necklace fern is one of several fern species tolerant of open, grassy or scrubby areas. You will find it more commonly in eastern areas, from North Cape to Invercargill, in lowland to lower- montane elevations.

Uses

We have seen no references to rongoā or other uses, for necklace fern.

See also

Category

Botany 2016

In The Hills 2016-02 < Index chronological > In The Hills 2016-04