8 October 2018 – Washington County Cactus Foray

Today, Joe Metzger and I went on a foray to locate two populations of cactus in Washington County, Maryland.

Voucher specimen of Opuntia cespitosa collected by Clyde Reed at Kemps Mill in June 1952



The first one was a reported population of Opuntia cespitosa in Kemps Mills where Clyde Reed collected a voucher specimen in June 1952. We drove the entire length of Kemps Mill Road and did not see any cactus. We also located Kemp Mill’s itself, but did not see a suitable habitat in the vicinity. Unfortunately, Reed’s voucher label does not reveal an exact location.  The only real clue was a reference to “limestone ledges.”




Snug Harbor Lane. Cliff is on the right

Along Kemps Mill Road, we spotted a limestone cliff face which could have been the “limestone ledges” referred to by Reed on the voucher label. We make a cursory look at the cliff face and did not notice any spot that might have supported cactus. We could not see the upper parts of the cliff from the road. These areas are more sunny and might be a good place to look another time. The cliff face however sported a lot of interesting flora.  It was located near a KOA campground and faced mostly to the west. We will attempt to locate the population again another time. Hopefully, we just missed finding it and the population is still around. If you have a good idea where it is located let us know.

Juvenile Cliff Brake Fern plants with some small Ebony Spleenwort.


On the cliff face, we spotted some presumed fern gametophytes and several fall blooming species in the family. It looks like an interesting site to return to in other seasons.


Lock house at Dam 5 with retaining wall at base.



We continued our foray to the Dam 5 area of the C & O Canal where there was a reported population of Opuntia humifusa s.s.This time we were successful. The cactus was located at the base of a retaining wall below a lock house. Based on the small size and location of the cactus population, we concluded that it was probably planted and not naturally occurring.

Opuntia humifusa below retaining wall at Dam 5






If you know of any other cactus populations in Washington County we would be interested in learning about them. There are some cactus populations in Allegany County which we will be trying to re-locate, probably next spring. If you think you might like to participate, there is plenty of time to plan a foray.



Here are some photos of other plants we saw while looking for the cactus.

Symphyotrichum lanceolatum (Willd.) G.L. Nesom –
Panicled Aster

Symphyotrichum lateriflorum (L.) Á. Löve & D. Löve. –
Calico Aster

Solidago flexicaulis L. –
Zigzag Goldenrod

Solidago caesia L. –
Blue Stemmed Goldenrod

Symphyotrichum shortii (Lindl.) G.L. Nesom –
Short’s Aster

Ageratina cf altissima (L.) R.M. King & H. Rob. –
White Snakeroot

Symphyotrichum sp. –
Unknown Aster

Laportea canadensis (L.) Weddell –
Canadian Wood Nettle

Ipomoea lacunosa L. –

Sicyos angulatus L. –
One-seeded Bur Cucumber or Star-Cucumber

Woodsia obtusa (Spreng.) Torr. –
Bluntlobe Cliff Fern

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