Blue Helmets

With a few notable exceptions (like prickly pear and the S1 plant I keep mentioning), there isn’t much blooming now in the Potomac Gorge. In the past week I’ve see a few long-leaved summer bluets and Venus’ pride, various Erigerons, and this: hairy skullcap (Scutellaria elliptica, Lamiaceae).

It’s one of nine species of skullcaps known in the Maryland piedmont, and the only one I see regularly. Look for it in dry, rocky woodland areas. This one was right along the towpath, and it may be the most perfectly-formed inflorescence I’ve ever seen on this species.


Lamiaceous Weeds Revisited

Now that I have a few more pictures, and now that the plants are blooming, I want to quickly revisit three mint family weeds. The first two are often confused, maybe because of similar habit and flowers.

The plant on the left is Lamium purpureum (purple deadnettle), and the one on the right is Lamium amplexicaule (henbit). Both have similar-shaped leaves, but the deadnettle’s are pointier, and note how long the petioles are on the lower portion. The henbit’s leaves are sessile and appear to almost surround the stem. Also, the uppermost stem leaves of the deadnettle are purplish (hence the specific epithet), though not on very young plants.


Lamium purpureum
purple deadnettle




Lamium amplexicaule




The third species is Glechoma hederacea (gill-over-the-ground, ground ivy, creeping charlie). Ground ivy’s leaves are close in shape to henbit’s, but they have distinct short petioles. Henbit spreads along the ground, but individual stems will stand straight up; ground ivy stays much closer to the ground.

Glechoma hederacea
ground ivy

More Lamiaceous Wildflowers

20160718-_dsc0004Physostegia virginiana
obedient plant, false dragonhead
Although obedient plant has a large range in the eastern US and Canada, there are only a few scattered occurrences in Maryland, including Montgomery County. I found these stands among the bedrock outcroppings in the Potomac River upstream of Fletcher’s Boathouse in DC. Obedient plant is a perennial that grows to about four feet tall, with late-summer blooming flowers on tall spikes. If it has plenty of soil moisture it can become aggressive, otherwise it makes a great garden plant that attracts bees, butterflies, and hummingbirds.


Pycnanthemum tenuifolium
narrow-leaf mountain mint, slender mountain mint
This perennial species grows to three feet tall in rocky areas and drier soils, like the rock outcroppings just upstream of the Marsden Tract. In Maryland it’s found throughout the piedmont and most of the coastal plain; its larger range is from eastern Texas to Quebec. Flowers are borne in terminal cymes.


Salvia lyrata
lyre leaf sage
Like obedient plant, lyre-leaf sage is a native perennial that does well in the garden, growing to about two feet tall, with flowers borne in cymes on the upper part of the stem. It’s related to kitchen sage (same genus) but is not particularly fragrant. It grows in moist soils in full sunlight in every county in Maryland; its greater range is from Texas to New York, where it’s endangered.


Scutellaria elliptica
hairy skullcap
Hairy skullcap is a perennial that grows in drier woodlands; look for stands of it near Carderock and the Marsden Tract (C&O Canal NHP) in early to mid June, when the flowers on terminal racemes start opening. The species ranges from Texas through Pennsylvania, and is found in most of Maryland.


Scutellaria nervosa
veiny skullcap
When I was still fairly new to this hobby I found a few of these plants near the Marsden Tract. After a little while trying to shoot them with a macro lens, I went home to identify them. I was surprised and pleased to learn that I’d found an endangered species (S1, highly state rare), but sadly I have never seen the plants since, despite hours looking every May and June. Veiny skullcap is a low-growing perennial, presumably liking rich, moist woodlands, since that’s where I found it. Flowers are borne singly or in pairs in the axils of upper stem leaves.


Teucrium canadense
American or Canadian germander
This widespread perennial is found in all of the lower 48 states and most of sub-arctic Canada, and is considered weedy by some authorities. It grows to about three feet tall, with flowers borne on terminal racemes. It’s in the same genus as the germander used in herb gardens, but has a much looser habit and likes much wetter soils. In the Potomac gorge I find it right on the floodplain, often in large colonies, particularly in late summer when the river is low.


Trichostema dichotomum
blue curls, forked blue curls, bastard pennyroyal
This annual species is widespread in the eastern US and Canada; in Maryland it’s found throughout the piedmont, coastal plain, and ridge and valley physiographic provinces. Look for it growing in drier soils in sunny areas. I’ve seen it by the dozens in Serpentine Barrens Conservation Park in Montgomery County, blooming in late summer. The plant grows to about two feet tall, with flowers borne in axillary cymes.

Lamiaceous Wildflowers

In addition to the weeds (see previous post), there are quite a few species of lamiaceous wildflowers found in the Maryland piedmont. Bloom times given below are based on my observations over the past few years.


Clinopodium vulgare
(formerly Satureja vulgaris) 
wild basil
Wild basil grows in much of Maryland, but I’ve never seen it here; this specimen was photographed in central New York. It’s a circumboreal species; in the US it’s found in the northeast, midwest, Four Corners, and Pacific northwest. This is not the same species as culinary basil (Ocimum basilicum). It grows to about a foot and a half tall in dry soils in sunny areas and open woodlands. Flowers are borne in cymes in the upper leaf axils.


Collinsonia canadensis
horse mint, richweed, stone root
This species is found in most of Maryland (but only parts of the coastal plain). It’s native to eastern North America, and is endangered in Wisconsin. It’s a fairly large plant, growing to four feel tall with a three foot spread in sandy and/or loamy soils in woodlands.  I’ve found two stands of richweed along the Cabin John trail; both sites are moist to wet and rather shady. Small flowers are borne on large terminal panicles in mid to late summer.


Cunila origanoides
common dittany, American or Maryland dittany, frost mint, stone mint, sweet horse mint, fairy skirts
Dittany is found from eastern Texas to southern New York late. There are records for it in most of Maryland, but I’ve only seen it once, in the woods at Serpentine Barrens Conservation Park in central Montgomery County. Dittany is a late-summer blooming perennial, growing to about two feet tall, with flowers borne in cymes or panicles in the upper leaf axils.



Lycopus uniflorus
northern bugleweed, northern water horehound
Lycopus virginicus
Virginia bugleweed, Virginia water horehound
Two very similar looking species, differentiated by leaf shapes, presence/absence of hairs on stems, shape of calyx teeth, and other little details. Both are moisture-loving perennials growing to about three feet tall, with tiny flowers in cymes in the upper leaf axils. The late-summer blooming flowers are not at all showy.



Mentha arvensis
wild mint, field mint
This species is not one of the culinary mints, but like them it can be an aggressive grower. It’s a perennial that grows to two feel tall in moist soils with some sun, blooming in mid to late summer. Flowers are borne in cymes in the upper leaf axils. A circumboreal species, it’s found in most of the US, except in some southern states, and is listed as weedy by some authorities.


Monarda clinopodia
basil balm, white bergamot, basil bee balm
Basil balm is on the Maryland RTE watchlist (S3); it’s found only in the piedmont and a few areas to the west. There’s one vigorous stand along the Potomac that I visit every year to see the bees carousing in the blossoms, from about mid June to mid July; like other Monarda species it’s a great attractor of pollinators. Its greater range includes most of the Appalachian states and parts of the mid-Atlantic, with some occurrences in southern New England and the midwest. It’s endangered in New Jersey and New York. The plants stand to about three feet tall, growing in moist soils in open woodlands. The flowers are borne in terminal cymes.


Monarda fistulosa
wild bergamot, bee balm
Except for California, Florida, and Alaska, and Rhode Island where it’s listed as historical, every state in the continental US has one of the seven varieties of M. fistulosa. In Maryland it’s found throughout the piedmont. Like many mint family species, this one can grow aggressively, spreading far and fast in ideal conditions. If you can keep it under control it makes a lovely garden plant that attracts several species of bees and butterflies. It can grow in sun to part shade, in many different types of soils, though it prefers drier ones. In humid conditions (eg, if overcrowded) it can develop mildew. Bee balm is a many-branched perennial growing to about 4 feet tall. The flowers are borne in terminal cymes. Despite the common name, it isn’t related to the bergamot that flavors Earl Grey tea (that’s Citrus bergamia, in the Rutaceae).

next time: more lamiaceous wildflowers

Lamiaceous Weeds

As I wrote in the previous post, about half of the mint family species found in the Maryland piedmont are alien. Some of those are seriously weedy. I regret not having pictures of all of them; perhaps this year I’ll make a point of getting good photos of aliens. Native or not, they are wildflowers…

Ajuga reptans
bugle, bugleweed, carpet bugle, carpetweed
This common ornamental groundcover is grown primarily for its ability to thrive in dry shade. It’s a handsome plant, with purple- or bronze-tinted or variegated evergreen or semi-evergreen leaves, and forms dense mats via above-ground stolons that run and form new plantlets. It’s established in much of the eastern US as well as the Pacific northwest. Whorls of blue-purple flowers appear on short spikes in late spring.
images at

Perilla frutescens
beefsteak plant, shiso
A popular herb in Asian cuisines, shiso is an escaped kitchen garden plant. There are vast swaths along the C&O canal from Great Falls to Carderock and elsewhere. Once I spotted a few women there harvesting the leaves. I had mixed feelings about that: on the one hand, destroy the invasives! On the other, foraging in national parks is illegal, and for good reason. Anyway, this plant can get to three feet tall, and features large, wrinkled, purple-bronze leaves that are heart-shaped and coarsely toothed. The small white flowers appear on racemes in summer.
images at


Prunella vulgaris
common self-heal, heal-all, all-heal
There seems to be some confusion about whether this plant is native to the US. ITIS recognizes three subspecies: P. vulgaris ssp. aleutica, ssp. lanceolata, and ssp. vulgaris20140821-dsc_0109BONAP shows two species in the US, P. vulgaris (native) and P. laciniata (alien). Presumably P. laciniata and P. lanceolata are the same. But then, according to the Weakley Flora there are both P. laciniata and P. vulgaris ssp. lanceolata. Whether alien or native, self-heal is recognized by several authorities as weedy. I see it blooming along the C&O Canal towpath, leading me to believe it likes sunny areas in dry, disturbed soils. It’s common there, but not exactly weedy. The blue or sometimes white flowers are borne in short spikes in mid to late summer.

There are three commonly confused, purple-flowering weeds that seem to be everywhere: ground ivy, henbit, and deadnettle. For more information, check out the post on


Glechoma hederacea
ground ivy, gill-over-the-ground, creeping charlie
This very low-growing plant has stolons up to seven feet long, forming new plants at the nodes, and thus covers large areas in mat-like growth. The small, round leaves have rather long petioles, are indented at the bases and have scalloped margins. The flowers are borne in pairs of cymes in the leaf axils, each cyme having only a few flowers. Ground ivy is established in most of the US and Canada (except the desert southwest), and is listed “potentially invasive, banned” in Connecticut. In the Potomac gorge there are areas many square feet in size covered in nothing but ground ivy.

Lamium amplexicaule
henbit, henbit deadnettle
Native to Europe, Asia, and north Africa, this low growing annual is established in almost all of the US and Canada except the Arctic regions. It’s a sprawling plant, but maybe not as mat-forming as ground-ivy, from which it’s distinguished by the leaves, which are about the same shape, but on the upper part of the stem they’re sessile so that they appear to entirely surround it. The stem is often red. The flowers are borne in sessile whorls in the leaf axils, and in terminal whorls.
images at

red dead nettle

Lamium purpureum
purple deadnettle, red deadnettle
Purple deadnettle is not quite as widespread across North America as henbit is. The green stems stand upright (instead of sprawling), and the uppermost leaves are somewhat purple or reddish. The leaves have a somewhat more pointed shape, short petioles, and occur only on the upper half of the stem.
images at

next time: lamiaceous wildflowers (the not-weedy kind)