Leaves, leaves, leaves....

Tofieldia leaves give away that it is a monocot: they are linear, with parallel veination.  Their form is described as an 'appressed fan', which as far as I can tell means they are in one plane:

 Photo: D. Iles

Like many monocots, Tofieldia's leaves are produced by a basal meristem (they are produced from cells at the center, just above the ground, and pushed up), and they appear to be produced continuously throughout the growthseason. However, it is unclear whether they overwinter or not. I can't find any information on this, but I have noticed that early-season leaves look like they have been around for a while, as you can see in this picture (taken on the 10th of June 2013, shortly after most plants started to produce leaves):

Photo: D. Iles

The leaves have fairly low nitrogen content (1.7%, putting it in the bottom third of the 40 plants in that community I have looked at) and they are also quite thick. Despite this, snow geese  (Chen caerulescens) seem to think they are quite tasty, as indicated by the damage they do to the leaves:

Photos: D. Iles


This plant grows under high light conditions where the "canopy" of dwarf birch and willow is thin or absent, and it is not usually moisture limited since it is found in tundra underlain by permafrost. The leaf morphology supports this: the leaves are thick and light green, and there is no way for the plant to elevate the leaves.

Tofieldia pusilla seeds and germination

 Tofieldia pusilla produces three carpels (female reproductive structures) with 15-30 ovules per ovary (Flora of the Canadian Arctic Archipelago, FCAA). This could result in 45-90 seeds maximum, but in the Canadian Arctic plants usually only have 6-18 seeds (FCAA). Why so few? This could be either a lack of pollinators (no fertilization) or a lack of resources (too expensive to turn all fertilized ovules into seeds).Seeds are small (0.5-0.6 mm long), smooth, and brown, and contained in fruits that are dry capsules:

Photo: http://nature.ca/aaflora/images/litopuu2.jpg.

Tofieldia seeds do not last long once they are rehydrated. Seeds stored as part of Kew Garden's Millennium Seed Bank Project were rehydrated and then batches were tested every few days for viability (Probert et al. 2009). Within 12 days viability had dropped to 50%, and within 30 days to 0%. This suggests that once seeds become sufficiently moisture to germinate in the spring, they either do so very quickly or not at all. In an arctic or subarctic environment that makes sense (plants that don’t germinate immediately won’t grow large enough to survive by the end of the summer) but it does leave open the question of whether the seeds obtain secondary dormancy and live to try another year.

References:

1. Flora of the Canadian Arctic Archipelago: http://nature.ca/aaflora/data/index.htm

2. Probert, R.J.,  M.I. Davis, and F.R. Hay. 2009. Ecological correlates of ex situ seed longevity: a comparative study on 195 species. Annals of Botany 104: 57-69.

This is Christa's example of the MyPlant blog for Introduction to Plants (Biol 239, University of Alaska Fairbanks, spring semester). As the semester progresses I will provide you with examples of how to answer the questions that will be posed weekly.

MyPlant #1: Why did you pick this species? Tell us something interesting about it.

I picked Tofieldia pusilla because it is a small, beautiful tundra plant that is not noticed by most people. I have been working on plants in subarctic tundra and saltmarsh on the Cape Churchill Peninsula (near Churchill, Manitoba) for the past couple of years, and this is one of my favourites.

Image: C. Mulder
(It's the little white guys - in bud form).

It is unusual in that it is a monocot that is not a graminoid, but it grows in a habitat where almost all monocots are graminoids. Right now I am also a little frustrated with this plant because I can't figure out whether the leaves overwinter or not - is it a "wintergreen forb"? I think it might be because early in the season the leaves already look pretty ratty.

You can find out a bit more on it here:
Montana field guide entry for T. pusilla

Please provide taxonomic information: Phylum, class, order, family. Are there any controversies with respect to it's classification? What is / are it's common name(s) (if any)?Who is the authority (the person who named the plant, usually provided as an abbreviation)?.

Tofieldia pusilla is in the phylum Anthophyta, class Monocotyledonae, order Alismatales. The family is unclear. According to the Flora of North America (www.efloras.com) it is Liliaceae, but according to the Flora of the Canadian Arctic Archipelago (http://nature.ca/aaflora/) it is Tofieldiaceae. The iplant Taxonomic Name Resolution site (http://tnrs.iplantcollaborative.org/TNRSapp.html) settles on Tofieldiaceae as well. Wikipedia gives a description of the history of placement of this genus in families; it sounds like it is still in flux.
Common names are small tofieldia, bog asphodel, false asphodel, Scottish asphodel, or fingerling (from the three sources listed above + Wildflowers of Churchill and the Hudson Bay Region, by Karen L. Johnson, Manitoba Museum of Man and Nature, 1987).

This plant was originally named by Michaux, then renamed by Persoon :
Tofieldia pusilla (Michaux) Persoon.