This will be the final blog post of my internship. One of the more interesting recent developments for me is finding Ptilimnium nodosum (Haparella) in the park in late July. This is a federally-endangered plant in the Apiaceae (Carrot Family). In the 2000s there was a major re-introduction effort within the canal between a professor at George Washington University and the National Park Service. From my understanding this re-introduction was not successful at establishing new populations, but some useful knowledge was gained through the experience and seeds from it were acquired for long term preservation. The last time a natural population was found on the main stem of the Potomac River was around 20 years ago. I hope I am giving enough of an overview while practicing a fair amount of discretion due to the sensitive nature of this information. I went to that location where it was last seen (a well-developed scour bar) and was surprised to find a decently-sized population in full flower. I think one could describe this as a meta-population.
Ptilimnium nodosum. Each umbel was rarely larger than a dime.
Ptilimnium nodosum. Even in flower these plants were hard to see. They grew alongside numerous wetland graminoids such as Juncus spp.
Ptilimnium nodosum. The leaves are referred to as phyllodes (reduced leaf petioles). They are hollow and segmented.
As I mentioned in a previous entry, the Potomac at this time of year is usually at its lowest point. I was able to walk out into the middle of the river and could have crossed into West Virginia on the other side if I desired.
From the middle of the Potomac in late July. The green is Justicia americana (Water Willow)
Another interesting plant I ran into with the help of a lady who has voluntarily been doing plant surveys along a portion of the canal for several years is the state-endangered Trachelospermum difforme (Climbing Dogbane). Not only had I never seen this plant before this summer, but I had never even heard of it. This plant is of particular interest to me because it resembles Japanese Honeysuckle morphologically and in growth habit. As I discussed in a previous entry, the canal is very interested in developing a robust volunteer Weed Warrior program. Part of my responsibilities involve educating these Weed Warriors about native look-alikes, especially state-listed species. I must admit that this one is tricky at first and would especially be difficult to less experienced eyes. Fortunately once you are aware of the plant, it is easily distinguished from Japanese Honeysuckle by its milky sap when leaves are present. On the other hand I can imagine some difficulties for volunteers because the two can grow intermingled in each other. This would be particularly hazardous if they are growing together, it’s late in the season and Japanese Honeysuckle is still green while Climbing Dogbane has gone dormant. The “hazard” being that dormant Climbing Dogbane is mechanically treated by someone thinking it is part of a honeysuckle clump.
Trachelospermum difforme. The milky sap I mentioned earlier.
Trachelospermum difforme. In flower. The manuals state that leaf shape is variable. Some of the leaves were quite oribicular with an acuminate tip. They resembled Oriental Bittersweet leaves to my eyes, though that vine has alternate leaves.
Trachelospermum difforme vs. Lonicera japonica (Japanese Honeysuckle). In my hand is Japanese Honeysuckle. As you can see the two grow alongside each other and can easily be confused as one species.
I went through the photos I took over the season and thought I would include some of the more interesting ones here for fun.
Automeris io (Io Moth) caterpillar on the state-listed Baptisia australis. Will sting you.
Eriocampa juglandis (Butternut Woollyworm) on state-listed Juglans cinerea (Butternut) leaf.
My internship still has a few weeks left but I feel the season waning. The asters will have their time and fall will be here soon. Cheers to a successful field season.
Coleman Minney
Field Botany Intern