Isoetes alpina
Common name
Alpine quillwort
Family
Isoetaceae
Flora category
Vascular – Native
Endemic taxon
Yes
Endemic genus
No
Endemic family
No
Structural class
Lycophytes (clubmosses, selaginella, quillworts)
Chromosome number
2n = 22
Current conservation status
The conservation status of all known New Zealand vascular plant taxa at the rank of species and below were reassessed in 2017 using the New Zealand Threat Classification System (NZTCS). This report includes a statistical summary and brief notes on changes since 2012 and replaces all previous NZTCS lists for vascular plants. Authors: By Peter J. de Lange, Jeremy R. Rolfe, John W. Barkla, Shannel P. Courtney, Paul D. Champion, Leon R. Perrie, Sarah M. Beadel, Kerry A. Ford, Ilse Breitwieser, Ines Schönberger, Rowan Hindmarsh-Walls, Peter B. Heenan and Kate Ladley.
2012 | Not Threatened
Previous conservation statuses
2009 | Not Threatened
2004 | Not Threatened
Distribution
Endemic. New Zealand: North and South Islands from the headwaters of the Waikato River and Lake Taupo south (near Whakamaru) south. Most common in the montane lakes, tarns and slow-flowing streams of the South Island.
Habitat
Montane to alpine, aquatic (rarely subterrestrial) at the bottom of lakes, rivers and streams (rarely growing near shoreline where it may be partially exposed during low water levels). Often forming extensive colonies in fine sediments or coarse sand.
Features
Aquatic, heterosporous, robust tufted herb arising from an erect corm. Roots long and stout, dichotomously branched. Leaves mostly sporophyllous, rather brittle, spirally (rarely flabellately) arranged, erect in tufts of up to 70, dark green, usually evenly septate, septae forming air chambers; lamina 50-250-500 (-750) mm long, linear to linear-filiform, tapered to an finely acute (rarely subacute to obtuse) apex, base swollen, up to 10 mm wide. Leaf appendages ligulate, ligule broadly triangular 1.0-1.4 mm long, located above the sporangium on the adaxial side. Sporangia adaxially located in pockets in leaf bases, large (up to 5 mm long) and conspicuous, oblong, heterosporous, Megaspores grey-white, mostly smooth, rarely minutely and obscurely tubercled; microspores minute, numerous.
Similar taxa
New Zealand Isoetes are in serious need of a thorough revision. As currently circumscribed the two species I. alpina and I. kirkii significantly overlap in most features except (mostly) the megaspore surface which in I. kirkii is finely though conspicuously tubercled, while it is usually smooth in I. alpina. The megaspores of I. kirkii are also usually white, whilst those of I. alpine are typically grey to greyish white.
Flowering
N.A. Spore producing
Flower colours
No flowers
Fruiting
N.A. Spore producing
Life cycle
Spongy megaspores are dispersed by water
Propagation technique
Easily grown in a fish tank ot fish pond planted in a coarse mix of sand and peat. Algal blooms area problem. Plants are very slow growing
Etymology
isoetes: From the Greek isos ‘equal’ and etas ‘year’, referring to the evergreen, unchanging character of the plant (Johnson and Smith, 1986).
alpina: From the Latin alpes ‘the Alps’, refers to plants growing in mountainous areas
Where To Buy
Not commercially available.
Attribution
Fact sheet including description prepared for NZPCN by P.J. de Lange (7 May 2011)
References and further reading
Johnson, A. T. and Smith, H. A (1986). Plant Names Simplified: Their pronunciation, derivation and meaning. Landsman Bookshop Ltd: Buckenhill, UK.
Thorsen, M. J.; Dickinson, K. J. M.; Seddon, P. J. 2009. Seed dispersal systems in the New Zealand flora. Perspectives in Plant Ecology, Evolution and Systematics 11: 285-309
NZPCN Fact Sheet citation
Please cite as: de Lange, P.J. (Year at time of access): Isoetes alpina Fact Sheet (content continuously updated). New Zealand Plant Conservation Network. https://www.nzpcn.org.nz/flora/species/isoetes-alpina/ (Date website was queried)