Myriopteris gracillima ecology

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Highest altitude (Washington): 1950 m, https://www.inaturalist.org/observations/128254588
and 1970 m, https://www.inaturalist.org/observations/134421823 and mostly on Rainier. May be absent or rare above 1,800 m further north based on Fourth of July trail (but also could be from recent fire).
Lowest altitude (Washington): 100 m, https://www.inaturalist.org/observations/107856027
and many others on lower Columbia river basin on the edge of maritime influence.

High local density: Myriopteris Rock, Horsethief Butte, Little Si, Icicle Creek near Fourth of July Creek TH.

My hikes with NO plants found: Bowl and Pitcher Riverside State Park (Spokane), Dirty Harry's Balcony via Birdhouse (didn't check climbing walls much), Echo Mountain bald, Goose Rock summit (Deception Pass), Iron Horse Trail to Ragnar, Iron Peak west approach (except for Teanaway Peak), Lake Lillian (Rampart Lakes backdoor), Mount Si (main peak), Nahahum Spring Creek Canyon, Peshastin Pinnacles, Rocks of Sharon (near Spokane), Sharpe Park (Sares Head balds), Sugarloaf Mountain (Anacortes), Whiskey Dick/Chinaman's Hat Mountain (not sure I looked well).

In our northern areas spring growth starts in April to May (or even June for high sites) and is pale green to whitish green (https://www.inaturalist.org/observations/123966618). Leaf curling/dessication may not occur at all or may occur from July through September, depending on site and summer precipitation.

At Icicle Creek sites, plants usually occur away from full sun when on south-facing rocks suggesting that the habitat is marginally wet enough. Should get better notes on this as it is not uniform and it doesn't appear to grow higher on Icicle Ridge (Fourth of July Creek, maybe partly fire recovery?). Probably a bit drier at Icicle Creek than Myriopteris Rock based on map gazing, but I really need to find good databases for precipitation and temperature.

"Myriopteris Rock" (my name) is a modest sized (approx 30m x 30m) bedrock protrusion just west of Salmon la Sac Road near the north end of Cle Elum Lake. It appears to be basalt, but it is not correctly labeled on https://geologyportal.dnr.wa.gov (probably an extension of nearby "Tertiary intrusive igneous rock"). It supports a large population (hundreds) of Myriopteris gracillima both in vertical and horizontal rock cracks with no obvious soil and on sloping surfaces that appear to have a thin soil cover over rock. The site will be covered in snow for at least a few months in winter, probably quite deep (will document later). All parts of the rock are easily accessible with a short walk on foot but appear to have only minor human disturbance except for a small flat area at the top. It is adjacent to a paved road with multiple houses nearby and with a convenient parking space for access. I anticipate that it is likely to be accessible nearly year round. There are some similar outcrops nearby, mostly on cliffs and slopes just east and southeast of Myriopteris Rock, but none are as accessible. They also support some Myriopteris but I haven't tried to survey them (most parts are extremely steep). Hikes nearby that are worth doing for local context include Hex Mountain and Sasse Mountain. The closest large ultramafic outcrop on the official map (https://geologyportal.dnr.wa.gov/) is about 8 miles to the NNE near Hawkins Mountain, but that map seems to exclude many smaller ultramafic sites.

Other plants on Myriopteris Rock are mostly mosses, grasses, Selaginella, and mat manzanitas (presumably A. nevadensis), some Cryptogramma, a few Penstemon fruticosis, Triteleia grandiflora, Rumex acetosella (Sheep's Sorrel not native, should be fine to pull it up), and probably scattered other Angiosperms that I have not yet recorded. There are Douglas Firs and Ponderosa Pines, mostly around the edges of the outcrop, but shade is generally minimal to none, except on the north side of steep rock. Cryptogramma acrostichoides is also fairly common, though the dominant fern is Myriopteris. I am fairly sure there are several Woodsia scopulina among talus on the NW side of the outcrop. There is Aspidotis densa nearby but none that I noticed on this outcrop. Most of the exposed rock appears weathered and is heavily populated with lichens, mosses, and Selaginella, consistent with long-term stable exposure. One north-facing cliffy section is heavily shaded and seems to have no Myriopteris, consistent with reduced sunlight (https://www.inaturalist.org/observations/130389674). Cryptogramma seems to replace Myriopteris in less sunny spots and my impression is that Myriopteris growing with even modest shade are smaller and have sparser fronds. Certainly all the big fat happy Myriopteris are in full sun, mostly on south facing slopes.

The Myriopteris Rock index observation is by cmaraist at location 47.330588, -121.106811 (+/- 3m)
https://www.inaturalist.org/observations/117790263

Little Si:
https://www.inaturalist.org/observations/119941573 (longitudinal study plant 1)
https://www.inaturalist.org/observations/135673227 (longitudinal study plant 2)

Apparent absence on Mount Si https://www.inaturalist.org/observations/117939338 - Mesozoic intrusive rocks

Posted on August 10, 2022 06:35 PM by

jhorthos

Myriopteris gracillima ecology

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