A Changing Scene Along the Hoosic and Hudson

Some places are so rich in botanical treasures that I return to them several times each year.  Canal Park at Lock 4 of the Hudson River/Champlain Canal is just such a place.  Here, the canal bypasses the Hudson rapids at Stillwater, NY, and rejoins the main river just downstream from where the Hoosic River flows into the Hudson from the east.  All that watery shoreline along both rivers, steep shale banks, surrounding forest, and alluvial floodplain provide habitat for a marvelous variety of native plants, easily accessed along trails that follow the waterways and wend through the woods.  The nature group I belong to, called the Thursday Naturalists, has visited this site many times, but we are always up to returning to sites as rich as this, especially when some of its most unusual plants are blooming. Mid-September is one of those times, so I paid a visit to Canal Park this week to check on how these plants were doing. Perhaps it was time for our group to revisit.

Standing at the junction of the rivers and gazing downstream toward the bridge at Mechanicville, I could see right away that the water in both rivers was higher than normal.  Many of the plants that thrive along both shores were now well under water, and the sandy strip of shoreline I usually explore at this point was now inaccessible without wearing waders.

I next made my way through the woods to a low floodplain where a curve of the Hoosic delivers rich alluvial sediments that encourage the plants there to grow to prodigious size. 

I was not prepared for the scene that met my eyes. Gigantic Sycamores still towered over the site, but an  equally huge Cottonwood tree had crashed to the ground, littering the flat area with heaps of broken limbs and leafy branches

While violent winds had toppled those Cottonwoods, raging floodwaters had delivered heaps of river-borne flotsam that now covered the trails we once walked to reach the shore. The footing here now seemed too treacherous for some of my Thursday Naturalist friends to navigate.

 I myself managed to teeter through this jumble of limbs and logs with hopes of finding a few of the many Green Dragon plants (Arisaema dracontium) that normally thrive to enormous size at this site.  And to my surprise, I did find one plant still standing, its cluster of brilliant-red fruit still attached to its stem and with rather tattered leaves still intact.

Thanks to that brilliant red color, I could spy many other Green Dragon berry clusters, crushed beneath heaps of Cottonwood limbs. I hope the plants that sprout next spring can make their way through the maze of all this blow-down.

I could see down the shore bright flashes of blue that told me Great Lobelia still bloomed some distance upstream, but I did not risk a fall by trying to get close enough to take a photo.  The footing along the flotsam-heaped sandy shore was truly daunting.  Instead, I moved downstream to where shale banks rose steeply from the water's edge. I had hoped to navigate a rocky ledge beneath the banks, but that ledge was now underwater, too slippery to risk wading over (as I knew from previous experience!).

At least I was able to access some parts of these shale banks, where one of New York State's rarest plants was still thriving.  I had counted over 200 basal rosettes of Provancher's Fleabane (Erigeron philadelphicus var. provancheri) on these banks a couple of years ago, and there may still be that many, sprouting from banks I could not see today. I did count a few dozen leafy rosettes clinging to the vertical shale banks that I was able to access.  

There were even a few Provancher's Fleabane plants still blooming.  The flowers look very much like those of the ordinarily abundant variety of Philadelphia Fleabane,  so how can this very-rare variety be distinguished?  Its distinctive habitat -- seasonally exposed and scoured calcareous bedrock of large rivers -- is a major clue, but the smaller flower size, shorter stem, scarcity of stem leaves, and the persistence of basal rosettes late in the year are further evidence that convinced a state botanist that the fleabanes growing here were indeed the real deal.

Many other interesting plants thrive on these steep shale banks, and I was particularly interested in two green leafy liverworts that were actually "in bloom" (meaning, they had developed some reproductive parts).  These flat leaves ("thallus") of the liverwort called Marchantia polymorpha are dotted with what are called "gemmae cups," receptacles that contain the developing sex organs. Later, two different structures, male and female, will emerge, the females looking like tiny palm trees, the males like miniature parasols.

This second green leafy liverwort is called Marchantia (formerly Preissia) quadrata, and I can see that some small reproductive parts have formed on the leathery thallus.

Here's a closer look at one of those reproductive parts, but I am not sure exactly how this species of liverwort produces its young and what function this tiny four-sided organ plays. If a liverwort expert informs me, I will return with details. 

The trail back to the parking area leads through a mixed hardwood/conifer forest high above the Hoosic river atop steep shale cliffs.  I could hear the full river rushing rapidly below.  In  other years, when the river was low, I could walk at the foot of these cliffs, enjoying the many interesting plants that grew there. Not today.

I did spy an interesting MOSS on the cliff face, however: little mounds of moss tipped with silvery "hairs". The moss looked like a number of little mice all napping on the rock. I dangled my feet over the edge of the cliff, trying to get a better view. But I had to lie down on my belly to reach down, clutching a nearby shrub with one hand, while I peeled off a small specimen. Such an unusual color for a moss!

It does look like a small furry creature, doesn't it?  I believe it is the moss called Grimmia pilifera, but if somebody who knows mosses better than I do corrects me, I will be back to add the correct name.

UPDATE: Turns out that this moss is NOT what I thought it might be, but is rather the globally rare species called Coscinodon cribrosus (Sieve-toothed Dry Rock Moss), as has been confirmed by expert bryologists, and my tiny specimen has been sent on to the New York Botanical Garden to be preserved in their permanent collections.

I was so happy to find a truly thriving population of Stiff Aster (Ionactis linariifolia) looking so perky and pretty.  Since their natural habitat is sunny, dry, and sandy soil, they sometimes look a bit dehydrated.  But we had lots and lots of rain this summer.  I think these asters were happy about it.  (The little spider seems happy, too.)

I don't think this Creeping Bushclover (Lespedeza repens) liked the weather this summer, though. I came here this week expecting this rare species of bushclover to be fully in bloom with its pretty pinky-purple flowers. But the hot days must have pushed its bloom time earlier, because all I could find were seedpods today, and its leaves were starting to turn yellow. Despite its presence in Rensselaer County not being recorded in the New York Flora Association's Plant Atlas, two ample populations do thrive at Canal Park. But they are not blooming now.

And here was another disappointment.  The tiny Whorled Milkwort with alternate leaves (Polygala verticillata var. alternifolia) is hard enough to find when it's in full bloom, but today it was obviously past its prime, with most of its florets and leaves long gone. I felt grateful to have found at least this withered remnant, since I have not found this milkwort at any other place than Canal Park.

But this sad little has-been of a flower was the clincher: this is not the year for the Thursday Naturalists to visit Canal Park in September.