We Have An Accord

Day 279: I've been waiting for Arnie's assessment for several days now, and it would seem we are in agreement regarding a species of Orchid not previously recorded in Mount Rainier National Park: Platanthera ephemerantha. That's harder to say than "Myriosclerotinia caricis-ampullaceae." We were put onto this lovely and tiny creature by another botanist who had seen it before it was in bloom. He thought it might be P. unalascensis, and asked me if I could check on it when it was flowering. We visited it on our way home from the abortive aurora mission, and as it turns out, it was the crown jewel of the day. I sent pictures to Arnie, but forgot to include the pertinent details as to how I keyed it out with Hitchcock. Here's our exchange so you can see what goes into determining the identity of a plant. There are a few missing pieces to the puzzle, but enough of them have come together to confirm Platanthera ephemerantha.

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From Arnie:
Okay, well, here we go.  To start off, I don't have experience with Platanthera ephemerantha, so here is my full reading of the Plantanthera key in Hitchcock.  Your photos are very good... but, this is a genus where you need to carefully measure flower parts, so need a ruler, or that penny you sometimes have in photos for scale.

Couplet

Leaves all on the lower 1/3 of the stem, often strictly basal, OR, leaves all cauline.

---Should have photo of entire plant to show entire stem.

---The leaves in photo all on lower 1/3 of stem, and my guess is that there are no more leaves higher on stem.

Couplet

Spur 0.7-1.3 mm, OR, spur 2-27 mm.

---This can be difficult to measure by looking at a photo with no ruler or scale bar.

---But 2 mm is just a little nub of a spur and these spurs are well developed, so I assume >2 mm

Then we come to this monster couplet:

a) sepals 3-several nerved, OR, b) sepals 1-nerved.  I can’t determine from photo. Sometimes if I can’t find the veins I guess at there only being 1, so slight possibility of b)

a) leaves 1-2, OR, b) leaves 2-5.  Well, in photo leaves are 2.  So not helpful.

a) leaves less than 5 times as long as broad, OR, b) leaves at least 5 times as long as broad.  It is awkward to measure leaves at an angle in photo, but I estimate leaves are about 6 times as long as broad, so b)

a) leaves basal, OR, b) leaves borne close together on lower 1/3 of stem but not all basal.  You know, the leaves attach above ground level (higher on stem than as seen in dandelion leaves) yet I usually think of cauline leaves as going higher on stem.  I can imagine different “experts” going either way and I don’t know Hitchcock’s criterium.  But since I see leaves on a stem, I lean towards b)

a) leaves not withering by anthesis (flowering), OR, b) leaves tending to wither by anthesis.  Clearly these leaves are not withered, but that “tending” to wither is ambiguous.  Note couplet b) takes you to P. ephemerantha which has leaves while in flower.

a) lip 5-20 mm, OR, b) lip 2-7 mm.  I estimate the lip (lowest petal) as around 5-7 mm, so this is not clear.

a) plants of mesic to wet areas, OR, b) plants mostly of dry areas.  Hmmm. Not a wet area, could be dry-ish.  I lean towards b)

Summary, I lean towards b)

Couplet

Spur 1.5-5.5 mm and less than or equal to lip, OR, spur 7-15 mm and much greater than lip.

---Spur is less than or equal to lip, which takes us to P. ephemerantha.  Can’t measure length better than to estimate it is within the range of 5 to 7 mm.

Platanthera ephemerantha

Sepals and petals bright white—yes.

Upper 2 petals +/- falcate (curved like a hawk’s beak), often converging—yes.

Lip becoming recurved towards spur by late anthesis (full flowering)—yes.

Inflorescence +/- loosely-flowered—well, yeah.

So this species is possible.

Platanthera elegans

Sepals and petals bright white—yes.

Upper 2 petals +/- straight and the tips generally diverging—no.

Inflorescence generally densely-flowered—no.

Not as good a fit.

 

I have never seen P. ephemerantha.  Congratulations!!!  Add another gold star after your name.

My reply:

Okay, I should have included some details which helped me key it out.

Leaves all on lower 1/3 of stem.

Spur roughly 7 mm.

Leaves at least 5 times as long as broad, closer to 6 as you surmised.

I'd have described the leaves as basal, having two plants in observation. I think the lower portion in the one photo had been disturbed and was therefore showing when it wouldn't have been otherwise.

Second specimen had leaves and was in full flower.

Lip equal to spur, i.e., 7 mm.

BONE-DRY area!