Pinnae of Woodwardia fimbriata
Today’s photograph is unrepresentative of the size of giant chain fern, whose leaves may reach a length of 1.7m (or 5.5 feet). Perhaps surprising to some local readers, this tropicalesque fern species is native from British Columbia south to Mexico’s Baja California.
Here’s a photo by Pete Veilleux@Flickr (aka eastbaywilds) with a person for scale:
The plant in today’s photograph is a 2007 accession growing in UBC’s British Columbia Rainforest Garden. I’ve had the pleasure of seeing (and collecting) Woodwardia fimbriata in both British Columbia and Oregon (though I did pay a toll for that Oregon collection–I hadn’t been stung by an insect in a couple decades prior to that). In British Columbia, where it is blue-listed, sizable populations of giant chain fern occur on Texada and Lasqueti Islands. It is sparingly found to the south of these islands in BC, with small populations on Vancouver Island and Salt Spring Island.
Habitat-wise, the Flora of North America entry for Woodwardia fimbriata reports that this is a species of forests where moisture is readily available. I observed this in Oregon; those plants were growing on a seasonally surface-wet slope with readily-apparent subsurface water movement in the soil. However, the main British Columbia populations growing on Texada Island (and presumably Lasqueti Island) do not at first glance conform to this requirement. As local readers will know, the Gulf Islands are subject to extreme dry conditions in the summertime. Does Woodwardia fimbriata have some measure of drought tolerance? Or, are the physical properties of the primarily calcareous soils with limestone bedrock on these islands a factor? Perhaps high water diffusivity or water retention in these soils? Does Woodwardia fimbriata have a competitive advantage in calcareous soils (or do other local species have a disadvantage?)? If any pteridologists or soil scientists are able to comment, that would be appreciated!
Does this die back each winter? I keep looking for it (at UBCBG) and not finding it. Is that because I’ve forgotten the exact location, or is it not there yet?
Here’s the location, on the left side of the path before the big tree on the right (note that there are 3-4 different fern species alongside the stream there). My photograph was from a year or two ago in early June. It isn’t looking terribly good this year so far, although some fronds are still unfurling.
It seems there permanently damp parts on Texada Island.
“There are extensive areas of low-lying ground between and adjacent to lakes in the study area. Some of these areas are poorly drained and swampy and are likely underlain with clayey and silty lake bottom material. There are also ‘strings’ of bogs and small lakes, that form, depending upon the depth of the present day water table.”
http://vananda-id.ca/watershed-maps/
The same could be said of the other Gulf Islands. Although, looking at the recorded habitat information for the specimen records, about 50% are from obviously wet / seep areas like ditches or steep slopes (that’s not where we saw a large patch, though).
I suppose there is a corollary question: why Texada and Lasqueti to such extent?
Here is a map of the specimen records–note that almost all of the outlier dots are incorrectly georeferenced and actually cluster with either Texada / Lasqueti / Vancouver Island (the few locations northwest of Victoria).
Otherworldly.
In Northern California the dark central strands in the rachis are used in basketry–are the islands known gathering sites? Or, being islands, are they buffered from temperature swings?
Here’s a picture to represent the underside of a frond. I took it at the Vancouver Island site that is the lowest left pink dot on the above map. We scrambled up beside a shaded (eastern exposure, forested) creek and found a healthy population of Woodwardia fimbriata close to the creek where their roots could consistently reach water.
Thanks, Judith!
From the couple-of-thousand hours spent in the redwoods of NorCal, this is an old friend, and I’ve seen spectacular specimens off of the Skunk Cabbage Trail in Redwood National Park.
What a beautiful plant, and that first photo is just stunning. Thank You!