Thursday, July 23, 2020

Queen Of Plants Without Chlorophyll

Day 284: About a week ago, I received an email from Arnie with the salutation, "Oh, queen of plants without chlorophyll," which was accompanied by a lovely photo of an Aphyllon species he'd found near Oregon Caves and a question about why he was seeing clumps of Castilleja at some points along the trail and Orthocarpus at others. I suggested that it might be because both plant genera are initial mycoheterotrophs (i.e., they require the assistance of a mycorrhiza to germinate), possibly even facultative mycoheterotrophs (ones which rely on a mycorrhizal "assist" even though they're capable of limited photosynthesis). Arnie likes to wind me up, and he's doing a fantastic job of it, keeping me posted almost daily on the mycoheterotrophs of southern Oregon. Damn, I wish I could take a road trip!

However, his salutation made me laugh, and also made me feel unashamedly proud of the fact that he turns to me when he has questions about mycoheterotrophic plants. In fact, it was my passion for mycoheterotrophs which inspired him to send me on a hunt for Cephalanthera austiniae, the Phantom Orchid. I think he thought it was a wild goose chase; I thought it was a snipe hunt, a way to keep me occupied and out of his hair for the rest of the season. We were both surprised when I got on the radio and announced breathlessly, "Arnie...Arnie...I'm kneeling beside two Phantoms!" as the tears streamed down my face.

That was several years ago. My botany partners and I have continued to monitor the site (the only place where Cephalanthera is known to occur in Mount Rainier National Park), and each year, we inventory Phantoms. With COVID hanging over our heads like the sword of Damocles, Joe and Sharon have gone alone twice, and last Sunday, Joe reported a census of 19 to me. This morning, I was out the door before sunrise with GPS and camera in hand. I only found 17 of Joe's specimens, but I also noted several large banana slugs in the area. I think that may be a clue into why some Phantoms disappear within a day or two and others live out their life cycle to set seed. In fact, I noted one old stalk from last year, its pods hanging dry and empty. So why is the Phantom so rare? Let's turn back to the discussion I had with Arnie: it requires a specific mycorrhizal partnership. In fact, Cephalanthera is more selective than other mycoheterotrophic species. Some combination of factors allows its existence at this site. We know that it occurs in the presence of certain other vascular plants ("plant associations"), so I believe it's possible that the mycorrhiza is dependent on something in the decaying detritus of these plant associates. Ah, so many questions! But I do know this: Cephalanthera austiniae is the true Queen of plants without chlorophyll. I am simply one of her vassals.

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