Summer Showstoppers

the Potomac River in early August, looking upstream from near Cabin John Creek

Spring is the time for the small, subtle things that emerge, grow, leaf out, bloom, fade, and die back to the ground before you know it. For many ephemeral species, you have two weeks at best to see the flowers.

thin-leaved sunflower stretching towards the sun

Summer, though… Summer is the time for big, showy, outrageous things. Plants taller than you are (joe-pye weed), leaves bigger than your hand (hairy leafcup), lurid colors (cardinal flower).  Many of these you won’t find in the woods, where flowers tend to be small (jumpseed, Indian-tobacco). The showy plants tend to like sunlight, so look for them in open woodlands, or at woods’ edge, or in meadows, or best yet, along riverbanks.

common evening primrose growing along a steep riverbank

That’s where I was last Monday and Tuesday. The weather was so nice, I couldn’t resist going to the Potomac Gorge to do some botanizing. Scrambling down steep banks and treading along the waterline I found over 40 different species of plants in flower.

Today I’m going to focus on the large yellow ones.


Common evening primrose (Oenothera biennis; Onagraceae) is found in every county in Maryland and most of the US.  It can grow over 6 feet tall in a variety of habitats. It’s hard to say how tall these were, as they were growing up a steep slope, but the ones closest to me were at least 5 feet.


Thin-leaved sunflower (Helianthus decapetalus; Asteraceae) is what we call a DYC*; these species can be difficult to distinguish, but this one can be identified by bracts under the flower head that exceed the width of the disk (click on the image to see it larger) and very long, narrow leaf tips (“acuminate” is the technical term). The specific epithet is not to be taken literally; the typical ray floret (“petal”) count is in the range of 8 to 15.

Hairy leafcup (Smallanthus uvedalia; Asteraceae) is another DYC, but this one is easily identified by the gigantic leaves with a unique shape. The few records in Maryland Biodiversity Project are mostly from the Coastal Plain and Piedmont, but a look at the USDA PLANTS Database distribution map makes me think that this species is under-reported. At any rate, I see hairy leafcup in the woods near openings in the canopy, close to the river but rarely in full sunlight. Usually I have to look up to see the flowers (I’m 5’5″ tall).

Here’s another big yellow astery thing: cut-leaved coneflower (Rudbeckia laciniata). The leaves make for easy field ID, but be sure to look at the whole plant; upper leaves are often much simpler in shape.

I was utterly thrilled to find this big, beautiful stand of purple-headed sneezeweed (Helenium flexuosum; Asteraceae) right by the river. Perfect habitat for this species: sunny and wet. How can you not love a flower with a name like that? Pearl crescent butterflies seem to love the flowers, too.

next time: big, showy, pink, purple


*damn yellow composite

Sand Dune Show

The Sonoran Desert’s wildflowers range from belly-flower sized to big and showy. Here are two of the latter. Although honestly, I took a lot of belly shots anyway. It was a sandy belly, sandy elbows kind of week.

Oenothera deltoides
dune evening primrose, desert evening primrose, birdcage evening primrose

There’s a native Oenothera species for every state in the Union except Alaska. Dune evening primrose is more widespread than many of them, and more widespread than many of the species I found in Anza-Borrego; it ranges from the Chihuahuan Desert north through the Sonoran and Mojave Deserts to the Great Basin Desert in Oregon, and also somewhat inland and along the California coast.

The plants I saw spread out along the sand maybe as much as three feet, and stood up to about a foot tall. I’ve read that in other parts of its range desert evening primrose can stand up to three feet tall. It’s described by various sources as both an annual and a perennial, so I’m not sure what to conclude there. One thing’s for sure, in Anza-Borrego at least it grows in association with this next plant. Almost any time I saw one, the other was there, too. Or close by.

Abronia villosa
desert sand verbena

Desert sand verbenas are not actually verbenas, which are in their own family. It’s in the four o’clock family (Nyctaginaceae). It is similar in size and growth habit to the dune evening primrose, but with a smaller range, being mostly restricted to the Sonoran and Mojave deserts, and some inland and coastal areas in California.

Take a look at the flowers. Looks like each has five petals, right? Not really. Another botanical oddity. More on that and other desert plants in the Nyctaginaceae next time.



There are at least six different species shown flowering in the first photo, and one plant not flowering but clearly a seventh species (not counting the dead ocotillo). Click on it to see it larger. This was one of the neat things about the super-bloom: so many different species growing together, forming crazy bouquets.

Flower of the Day: Common Evening Primrose

Oenothera biennis; Onagraceae (evening primrose family)


Sixty six species of Oenothera are found across the US, all but five of which are native. This one is the most widespread; it can be found everywhere except the arid West.  Some authorities list it as a problematic weed.


The plant can grow to six feet tall, though three feet is more typical.  Flowers open in the evening and close in the morning, though they may stay open longer if the skies are overcast.  I found this plant mid-morning on one of those weedy low rocky bluffs that jut into the river. Those areas are often covered in poison ivy and alien invasives, but I almost always find something really interesting there, too.

Enchanter’s nightshade (fotd 6/23) is another plant in the evening primrose family.  So is this weedy looking thing:


That’s seedbox (Ludwigia alternifolia).