Diario del proyecto Invader Detectives: National Capital Region

As the spring season reaches its prime and many plants begin to re-emerge, one plant to watch out for is christmas berry (Photinia villosa). Native to temperate Asia, this species was introduced to the US as an ornamental plant that is valued for its year-round beauty. However, christmas berry poses a significant ecological threat by creating dense shade and thickets that prevent native seeds from germinating and growing.

Birds are attracted to its fruits and play a role in spreading the seeds throughout native forest edges, riparian corridors, and roadsides (Lower Hudson PRISM, 2023). It’s also noted to not cut or mow christmas berry because the roots will react and increase the plant’s density. If a small plant is found in your yard, make sure to pull out all of its roots.

A dense thicket of christmas berry growing along the right side of a trail, Katja Schulz (CC BY), iNaturalist

Identifying Christmas berry

Christmas berry is a multi-stemmed shrub found near native forest edges and floodplains when it escapes cultivation. The leaves are simple, obovate to oblong-obovate with serrated margins, and arranged alternately along the stem. The upper leaf surface is bright green and pale green with fine hairs on the underside. When young, the leaves are fuzzy with hairs, which diminishes as they mature, persisting only along the veins on the underside of the leaf. The young stems of christmas berry are reddish-brown to dark brown, maturing to gray with distinct orange lenticels. Buds along the stem are brownish and less than ¼ inch long. In May, creamy, white, 5-petaled flowers with green stamens appear in flat-topped clusters of 10-20+ at the end of the branches (Flora of China, n.d.). Bunches of red, oval fruits, resembling small cherries, appear in late summer and persist through the winter. Each fruit contains 1-5 seeds. In the fall, the leaves of christmas berry display vibrant hues ranging from yellow to red.

Fall leaves with ripe fruit, Patricia Butter (CC BY-NC), iNaturalist

Native Look-a-Likes

Christmas berry looks similar the native red chokeberry (Aronia arbutifolia), which can make identification difficult, particularly in the fall when only leaves and fruits are present. Both plants have obovate to oblong-obovate serrated leaves, that are bright green and finely pubescent (hairy) along the underside vein.

Native look-alike: Red chokeberry, Andrey Zharkikh (CC BY 2.0)

The flowers of both species are 5-petaled, white and presented as clusters at the end of stems, which develop into red fruit that persist through winter (North Carolina State University Extension, n.d.).

The differences between christmas berry and red chokeberry are subtle but significant. Red chokeberry grows in a wider variety of habitats from mesic to wet soils and has a ‘neater’ vase-like growth form, versus the dense, shrubby form of christmas berry. Red chokeberry leaves emerge in the summer and are elliptic with bright purple hairs along the midvein of the leaf’s upper surface. In contrast, leaves of christmas berry are obovate in shape lack the characteristic purple hairs, instead having a white pubescence on underside of the leaf. Buds on red chokeberry are approx. ½ inch long and red, while its flowers are white with pink hues that showcase bright red to pink stamens in April. In contrast, christmas berry buds are much smaller at ¼ inch and flowering occurs later, from May to early June with the flowers producing green stamens. Red chokeberry flowers develop into red clusters of fruits that are round compared to the yellow-ish or red oval fruits of christmas berry. Similar to christmas berry, red chokeberry also has gray bark; however, it lacks the characteristic orange lenticels and instead has dark, diamond-shaped fissures as it matures.

A. Christmas berry leaves B. Lower surface of leaf

C. Red chokeberry leaves D. Lower surface of native leaves E. Purple hairs along midvein

F. Mature christmas berry bark G. Young christmas berry bark with orange spots

H. Mature chokeberry bark with widened fissures I. Young chokeberry bark with diamond-shaped fissures.

J. Christmas berry bud K. Red chokeberry bud

L. Christmas berry flowers M. Red chokeberry flowers

N. Christmas berry fruits O. Red chokberry fruits

Photo Credits: A. kellycarrot (CC BY-NC); B. josh_rudder (CC BY-NC); C. Ken Kneidel; D. & E. Dwayne Estes (CC BY-NC), iNaturalist; F. Bradley Simpson; G. sus_scrofa (CC BY), iNaturalist; H. Bradley Simpson; I. Yvonne Ng; J. & K.Bradley Simpson; L. tosakah(CC BY-NC; M. Scott A. Davis (CC BY), N. Uri Sarig (CC BY-NC); O. Laura Clark (CC BY), iNaturalist.

Tips for making a good observation on iNaturalist

Note: The scientific name for Christmas berry on iNaturalist is Pourthiaea villosa.

Take photographs that show:
-The landscape around the plant – this shows the habitat
-If they are flowering, photograph a whole plant including flowers and leaves
-If not flowering yet, photograph both surfaces of a whole, typical, undamaged leaf. With christmas berry, you should be able to see fruits during late summer

Make comments that:
-Are explicit about the issue of cultivated plant vs weed
-Provide the location or landmark, or which direction from a trail or path
-Give a rough estimate of the number of plants and the area covered any other comments you think might be helpful

Welcome to the Invader Detectives project page! Invader Detectives is a project of the National Invasive Species Council, and it's pilot is being implemented by the National Capital Partnership for Invasive Species Management (NatCap PRISM).

Incised fumewort is a highly invasive plant that is new to our region. It has a devastating impact on our native wildflowers, and is very difficult to manage National Park Service. You can help protect your park by scouting for incised fumewort and reporting it. To do this, head out to a stream valley park when the stalks of little purple flowers are conspicuous, from the second week of March into the first week of April. Take photos and upload them using the iNaturalist app. Here's a great video about how to make an observation on your smartphone.

Here are some tips for making an incised fumewort observation. Take at least one picture of the whole plant and one to help others to find the precise spot. Include any distinguishing landmarks in the location photo, like the edge of a path or a larger tree. In the notes section, please tell us anything you think we need to know about the plants, the size of the infestation, or the location. In late March and early April we are especially interested in whether the seed pods have started to explode. If you are making the observation in a garden, information from the gardener can be very useful (when the infestation arrived, how it got there, management efforts).

You’re done! You can go to your observation at any time by using your phone app, or by visiting the iNaturalist website.

Volunteers in Arlington County map a small patch of incised fumewort. March 17, 2023.
Photo credit: Toni Genberg

A few things to keep in mind: 1. Unfortunately, a park system that lacks sufficient resources (staff, money, volunteers) may be unable to manage the incised fumewort that you have reported. 2. Most park systems prohibit visitors from managing vegetation. Unless you are authorized by park staff, please just report the infestation, do not attempt to manage it.

Incised fumewort is just one of the Early Detection / Rapid Response species being tracked by Invader Detectives. If you would like to join the Invader Detectives listserv, email stangren@mwcog.org and put “listserv” in the subject line.

Visit us on Instagram @NatCap.PRISM.

Hello Invader Detectives!
The best season of the year is just around the corner, which also means a bunch of viburnums will be fruiting (checks watch)... now.

There are a plenty of invasive viburnums to lookout for on the Invader Detectives project page, but
I’ll be going over 5 of them:
Viburnum dilatatum (linden arrowwood),
Viburnum plicatum (doublefile and snowball viburnum),
Viburnum sieboldii (Seibold viburnum)
Viburnum setigerum (tea viburnum), and
Virburnum x rhytidophylloides (lantanaphyllum viburnum).

These viburnums are all native to East Asia, primarily China and Japan, brought in for ornamental use and are still sold commercially. They outcompete native flora, including our own native viburnums, due to dense growth and vigorous growth.

You can also check out Cornell’s Guide to Identifying Viburnums and their express key but note that there will be some variation when keying.

What do these species have in common?
Viburnums are a deciduous, woody shrub to small trees. The leaves for all the species listed are in opposite arrangement (i.e, mirroring each other). Flowering occurs April through August and fruits will start to appear between late August through September. Their flowerheads are flat-topped with clusters of creamy, white, star-shaped florets that boast 5 long stamens and later form clusters of droopy fruits. Of course, there will be some exceptions to these characteristics.

Viburnum dilatatum

Photo credits (Left to Right): msperr , esummerbell , henryfrye , garysmith4 , emilio_c , masebrock

Linden arrowwood (Viburnum dilatatum) can get up to 8-13 ft tall. They have a habit of forming dense thickets and suckers that take extra nutrients from the parent tree. Of all the viburnums, the leaves on V. dilatatum are most egg-shaped and soft to touch as it has hairs on both sides of the leaf with a silverish underside, though this can give the leaves a dirty look since they trap dust. It is worth mentioning that V. dilatatum has the most variation in leaf shapes, even along the same stem. When confirming if it is V. dilatatum, you can check the back of the leaf and see if there are two to four little indentations or glands at the base of the leaf. Young stems are fuzzy with small orange lenticels that will mature to gray-brown color and smooth texture with prominent orange lenticels.
The flowerheads on V. dilatatum are flat topped and may have an unpleasant smell. When looking at the tubular, star-shaped flowers, the petals are rounded. In autumn, the leaves will turn dull red before falling and yellow 5-8mm fruits start to appear. Soon, they will mature to a red color and persist through winter. The fruits of this species are often oblong and may be shaped like the flame of a candle. Most other viburnum species have round fruit.

Viburnum plicatum f. plicatum (Japanese Snowball) and Viburnum plicatum f. tomentosum (Doublefile viburnum)

Photo Credit: reuvenm , shuufly , cuihenggang

Japanese snowball (Viburnum plicatum f. plicatum) is a cultivar of the naturally occurring doublefile viburnum (Viburnum plicatum f. tomentosa). The two are often grouped together when talking about Viburnum plicatum, so I decided to separate them since they have some different characteristics.
Japanese snowball can be considered a small tree as it can group up to 15ft tall. As the common name suggests, the flowers are bright white and round. You’ll see these snowball flowers in opposite arrangement growing from the nodes. Japanese snowball is sterile and cannot cross-pollinate or produce fruit; they don’t have any fragrance to them as well.
Leaves are a dark green with pleated surface, a hairy underside, ovate, and can turn burgundy to purple in autumn. The bark of the trunk is dark gray-brown, hairless, and can have a smooth or ridged texture.

Photo Credit: phaynes

Doublefile viburnum (Viburnum plicatum f. tomentosum) is the fertile version of Japanese snowball. Like many older-younger sibling dynamic, this older sibling can reach only up to 10ft. As far as I could find, they share the same leaf characteristics, with the ovate, dark green, pleated surface, hairy underside, and autumn foliage. In both of these varieties the leaves will have many pairs of veins, typically no less than 11 pairs and often up to 16 on each leaf.

Photo Credits: conuropsis (left and middle), lynnharper

The bark for doublefile is also gray-brown with orange spots throughout the trunk. While the trunk is smooth and hairless, the younger stems are densely hairy. The flowers are not as showy as the other form but have a sweet fragrance. These flowers are a creamy yellow compared to the typically creamy white color of the rest of the viburnums listed here, and are surrounded by showy, bright white bracts (sterile flowers) that each have 4 to 5 petals. The fruits on both forms of this species first occur red and mature to black.

Viburnum sieboldii
Siebold’s viburnum (Viburnum sieboldii) is the tallest amongst its brethren, a 15-20ft tall giant. The leaves on Siebold’s are lanceolate to oblong shape, are dark green with a pale underside, and have no hairs on either side; when crushed, they smell like burnt rubber.
Siebold’s flowers are similar to Viburnum dilatatum but less rounded at the tip of the petal. In August to September, red fruits occur on red stems; when ripe, the fruit will turn black.

Photo Credits: cgrove79, kemper, kitmonster, tkr421, matthewhalley, tkr421

Viburnum setigerum

Photo Credits: josh_rudder, wefwef, spmarkle, jim_keesling(last two)

Tea viburnum (Viburnum setigerum) grows between 8-12ft tall and forms a vase shape. The leaves are lanceolate to oblong, green-blue-silver to dark green in color, have hairs along the back side of the veins, and slight teeth along the margins. During mid-summer, the foliage becomes a unique muted red in between the veins. The flower is most similar to Viburnum dilatatum with similarly shaped petals though with a pleasant smell instead. The flower head appears in much smaller clusters: 1 to 2 inches in diameter compared to the other viburnum inflorescences here being 2 to 6 inches in diameter. In September, the fruit will emerge as yellow-orange and mature to red.

Viburnum x rhytidophylloides
Viburnum x rhytidophylloides is probably the most unique of the viburnums on this post; this is a hybrid between V. lantana and V. rhytidophyllum, both of which are non-native to the US.
Viburnum x rhytidphylloides is a semi-evergreen shrub, meaning that some leaves can be entirely evergreen or just partially fallen if the winter is mild enough. As the plant matures, it begins to mound and grow suckers at the base of the trunk. The foliage is dark green on the front and pale on the underside with entire or sparsely toothed margins. The leaves can be lanceolate to oblong with a crinkled appearance and become wind-burned, especially in the winter. They also have hairy stems that emerge as a fuzzy green-white and become brown-orange as they mature. The inflorescence is more rounded at the top and is clustered tightly together with an unpleasant smell.
This hybrid is able to clone and produce red to black fruit, but best fruit production takes place when one or both parents are present. While V. x rhytidophylloides is not common in the wild within the region , iNaturalist observations of one of the parents, V. rhytidophyllum, have increased over the past 3 years. This could present an issue in the future.

Photo Credits: derwinmcg, jdr2
For more photos and ID, you can check out North Carolina University's Extension Plant Toolbox.

Tips for making a good observation record of species
Take photographs that show:
the landscape around the plant – this shows the context and offers a clue to the scale of the
infestation
if they are flowering, get a close-up photo of the flowers
if they aren’t flowering yet, photograph a whole plant since some of these have different growing habits, and the leaves and stems

Make comments that:
are explicit about the issue of intentional plant vs weed vs escaped
give a rough estimate of the number of patches and the area covered
any other comments you think might be helpful

References
Brand, Mark and University of Connecticut, Department of Plant Science and Landscape Architecture. “Viburnum Setigerum: Tea Viburnum.” University of Connecticut Plant Database, plantdatabase.uconn.edu/detail.php?pid=537. Accessed 27 Sept. 2023.
Missouri Botanical Garden. “Viburnum x Rhytophylloides ‘Alleghany.’ Plant Finder, https://www.missouribotanicalgarden.org/PlantFinder/PlantFinderDetails.aspx?kempercode=g260#:~:text=Viburnum%20%C3%97%20rhytidophylloides%20is%20a%20hybrid%20viburnum%20(a,to%208-10%E2%80%99%20tall%20(sometimes%20more)%20and%20as%20wide, Accessed 20 Oct. 2023
North Carolina State University. “Viburnum Plicatum.” North Carollina Extension Plant Toolbox, plants.ces.ncsu.edu/plants/viburnum-plicatum. Accessed 27 Sept. 2023.
---. “Viburnum Plicatum F. Tomentosum (Doublefile Viburnum).” North Carolina Extension Gardener Plant Toolbox, plants.ces.ncsu.edu/plants/viburnum-plicatum-f-tomentosum. Accessed 27 Sept. 2023.
---. “Viburnum Setigerum (Tea Viburnum).” North Carolina Extension Gardener Plant Toolbox, plants.ces.ncsu.edu/plants/viburnum-setigerum. Accessed 27 Sept. 2023.
---. “Viburnum Sieboldii (Siebold Viburnum).” North Carolina Extension Gardener Plant Toolbox, plants.ces.ncsu.edu/plants/viburnum-sieboldii. Accessed 27 Sept. 2023.
---. “Viburnum X Rhytidophylloides (Lantanphyllum Viburnum).” North Carolina Extension Gardener Plant Toolbox, plants.ces.ncsu.edu/plants/viburnum-x-rhytidophylloides. Accessed 27 Sept. 2023.
Rawlins, Karan. “Viburnum Sieboldii/NJ - Bugwoodwiki.” Bugwood Wiki, edited by Susan Brookman, 22 Aug. 2014, wiki.bugwood.org/Viburnum_sieboldii/NJ. Accessed 27 Sept. 2023.
“Sibold Viburnum : Viburnum Sieboldii.” Pennsylvania Department of Conservation and Natural Resources, elibrary.dcnr.pa.gov/PDFProvider.ashx?action=PDFStream&docID=1738687&chksum=&revision=0&docName=Siebold+viburnum&nativeExt=pdf&PromptToSave=False&Size=268822&ViewerMode=2&overlay=0. Accessed 27 Sept. 2023.
US National Arboretum. “Viburnum ×Rhytidophylloides ‘Alleghany.’” US National Arboretum, www.usna.usda.gov/assets/images/as_pdf_image/Viburnum_x_rhytidophylloides_Alleghany.pdf. Accessed 27 Sept. 2023.
Virginia Tech College of Natural Resources. “Range Map Information.” Virginia Tech Dendrology, dendro.cnre.vt.edu/dendrology/maps2.htm. Accessed 27 Sept. 2023.

Happy Tuesday Invader Detectives!

Chinese fountaingrass (Cencrhus purpurascens), esummerbell (CC 4.0), iNaturalist, Cenchrus spikelet, Steve818, iNaturalist

Ever see this fuzzy hot dog around town? The term for the flower head above is ‘bottle brush’, but the common name for the look-alike is called bottlebrush grass, so for now, it’s fuzzy hot dog. Chinese Fountaingrass (Cenchrus purpurascens) is native throughout East Asia and Australia and sold for ornamental use; instances of escaping are increasing (Lee, 2023). There are different cultivars, so some features may differ. It’s really easy to spot as a landscaping plant for plazas and housing complexes.

Cenchrus is a deciduous perennial grass. It is clumpy and grows up to 5 ft tall (North Carolina State University Extension, n.d). The leaves are linear, long, and flat in alternate arrangement, and will start to emerge in early spring. When brushing your fingers against the leaf blade, there will be resistance against doing so. The leaves and flowers change from green to amber in summer through early fall (Brookman, 2015). The leaf blade is hairless, but few tiny hairs create a collar where the leaf and stem meet. The flower’s stem is hairy and may change from a round stem to a square stem from the start of the head.

Seeds spread by bird and wind; they also have bristles that allow the seed to adhere to passersby. These bristles stick outward and whorl around the seed.

Look-alikes
Bottlebrush grass (Elymus hystrix)

Elymus hystrix, mefisher, iNaturalist;flowerhead with two spikelets in opposite arrangement, jim-bowhay, iNaturalist

Our native bottlebrush grass (Elymus hystrix) has a similar flower shape yet looks more delicate. Cenchrus and Elymus have different color ranges; Cenchrus changes from green to purple, and Elymus is green-gray-blue to bright green as shown in mefisher and jim-bowhay’s photos above (Brookman, 2015).

Elymus has 2 spikelets alternating up the stem with 2-4 bristles on each spikelet. The leaf collar on the native has little to no hairs, whereas there will be little to some fuzz on the Cenchrus.

Elymus leaf collar, megachile, iNaturalist; Cenchrus leaf collar, davidenrique (CC 4.0), iNaturalist

You may not find these plants in the same habitats. Cenchrus is likely to grow in moist soils anywhere from full sun to partial shade; Elymus is typically found in drier soils in shady areas where the sun shines through the canopy (NCS Extension, n.d.; NCS Extension, n.d.).

Tips for making a good observation record of Chinese fountaingrass

Take photographs that show:
Area where they were found
Infestation/population
photograph a whole plant including flower head, stem, spikelets, leaves, and leaf collar

Make comments that:
Are explicit; if they are intentional or wild
give a rough estimate of the number of bunches and the area covered
any other comments you think might be helpful

References
Brooke, Susan. 2015. Pennisetum alopecuroides/NJ. Retrieved 8/16/23 from https://wiki.bugwood.org/Pennisetum_alopecuroides/NJ
Davidenrique. 2021. Photo. Retrieved 8/16/23 from https://www.inaturalist.org/observations/96793616
Esummerbell. 2022. Photo. Retrieved 8/16/23 from https://www.inaturalist.org/observations/133666411
Jim-bowhay. 2021. Photo. Retrieved 8/16/23 from https://www.inaturalist.org/observations/85939977
Lee, M.T. 2023. Cenchrus purpurascens. Flora of Southeastern United States by North Carolina Botanical Garden. Retrieved 8/16/23 from https://fsus.ncbg.unc.edu/show-taxon-detail.php?taxonid=2232
Mefisher. 2022. Photo. Retrieved 8/16/23 from https://www.inaturalist.org/observations/120074698
Megachile. 2019. Photo. Retrieved 8/16/23 from https://www.inaturalist.org/observations/28824913
NCU Extension. n.d. Cenchrus alopechuroides. Retrieved 8/16/23 from https://plants.ces.ncsu.edu/plants/ely

Hi Invader Detectives!

Summer is just around the corner, but that’s not stopping invasives from taking over. Wavyleaf basketgrass (Oplismenus undulatifolius) is getting ready to flower and we need to be on our toes. Otherwise, they’ll reach ours!

Left: andy71; Right: davidenrique

Wavyleaf basketgrass is a shallow-rooted perennial that grows no longer than 1.5ft (Virginia Department of Conservation and Recreation, 2022). It has stolons, an above-ground root system, that allows them to easily creep along the surface and create a carpet. Their shallow roots make them easy to pull out, but if doing so, make sure to take the entire plant as they can resprout. Basketgrass leaves are simple, entire, with alternate arrangement and a terminal leaf. The leaves are attached to the stem and while they appear to clasp around the stem, they do not. Looking at andy71’s photo, you can see that it is wavy across the leaf. The leaves will die back in the winter and re-emerge in the spring (University of Maryland, n.d.).
Flowering from August through November, the inflorescence will occur toward along the end of the stem as seen in davidenrique’s photo (Virginia Department of Conservation and Recreation, 2022). The seeds are super small and sticky. You’ll know you’ve walked through some wavyleaf when you’ve got tons of tiny seeds sticking to you, so check yourselves and your pets as you’re out and about (Spencer, Flessner, & Barney, 2020).
Wavyleaf basketgrass is a shade tolerant species that can be found in full canopy forests, full shadye riparian habitat, and forest edges (University of Maryland, n.d.).

 
Look alikes

Small carpet grass (Arthraxon hispidus)

Left and right: mefisher

Before seeing real-life wavyleaf, I found some carpet grass while hiking through Rocky Run and took a good 20 minutes comparing it to online wavyleaf photos and descriptions before using Seek that told me in two seconds. I kept trying to convince myself that the carpet grass in front of me was wavyleaf but small enough to be slightly off. Still invasive.
They are both low-growing and creeping grasses, like moist soils, similar leaf shapes and arrangement, and have the ripples across the leaves. The similarities seem intimidating, but here’s where you can tell the difference: the leaves are heart-shaped and short that does clasp around the stem. Carpet grass will choose sunny over shady areas, and flowers from September to November with the flowerhead at the end of the stem (National Parks Service & United States Forest Service, 2010). Take a look at davidenrique’s photo of wavyleaf and compare to mefisher’s carpetgrass photo!

Japanese stiltgrass (Microstegium vimineum)

Left: craigmartin, right: hb2000 (CC BY-NC 4.0)

Japanese stiltgrass and wavyleaf basketgrass can be confused with each other as they may cohabitate similar areas and have a similar leaf shape. They grow densely wherever you may see them. When differentiating the two, Japanese stiltgrass has a silverish midrib on the leaves that almost looks reflective. Instead of carpeting the surface as basketgrass does, stiltgrass stays upright.

Deer tongue (Dichanthelium clandestinumDichantheleum clandistinum)

Left, gillydilly Right: sanguinaria33 (CC BY-NC 4.0)

Deer toungue is our native grass that is much easier to distinguish from wavyleaf basketgrass. Deer tongue will grow in clumps instead of spreading through stolons. The leaves on deer tongue appear much more intimidating with it’s sharp-looking shape. The base of the leaf clasps around the stem, while basketgrass does not. When deer tongue flowers, it branches out little buds to reveal pink to purple florets.

Tips for making a good observation record of wavyleaf basketgrass
Take photographs that show:
Area where they were found
Infestation/population
An entire stem
if they are flowering, photograph a whole plant including flower head, spikelets, and leaves
if they aren’t flowering yet, photograph a whole, typical, undamaged leaf.

Make comments that:
are explicit about the issue of intentional plant vs weed vs escaped (You’d be surprised but
some parks include intentionally planted alien plants which are now invasive – life is
complicated!)
give a rough estimate of the number of patches and the area covered
any other comments you think might be helpful

https://www.inaturalist.org/observations/94042721

Hello Invader Detectives!
Have you seen a plant with white flowers and bright green leaves? Sounds like dogwood, blackberry, even honeysuckle, right? Today’s post is highlighted on black jetbead (Rhodotypos scandens). Spring has sprung and the shrubby jetbead is now in bloom.

Jetbead by huntingbon

Since jetbead is currently flowering, it’ll make it easy to spot. Flowering typically occurs from late April through early May (Midwest Invasive Species Information Network, n.a.). The flowers have 4 white, wide petals with white to pale yellow stamens and are terminal, meaning they occur at the end of a branch.
Jetbead has bright green leaves that are double serrated and in opposite arrangement. The leaves have a wide, round base and a narrow tip. The backside of the leaf is somewhat hairy and doesn’t change in color. This shrub is deciduous, so don’t expect to see any leaves in autumn (MISIN, n.a.). Having no leaves doesn’t mean that Rhodotypos will be hard to identify in the winter; four chestnut-colored fruits will be emerge from the flower and mature in the fall to be shiny, black, and bead-shaped (MISIN, n.a.). These fruits will persist through the winter on the shrub’s arching stems.

Jetbead by huntingbon

Jetbead is a very recognizable plant; native flowering dogwood (Cornus florida) was the only plant that could potentially be confused with jetbead. The most notable difference is Cornus is a tree while Rhodotypos is a shrub. Yes, there can be fine line between shrub and tree, but jetbead reaches to 6ft while dogwood reaches 30-40ft at maturity (Swearingen & Fulton, 2022; University of Kentucky, n.a.).
With that said, there are many similarities where they may be confused, especially on iNaturalist where it might be difficult to identify some photos of plants. Flowering dogwood and jetbead follow similar phenology: flowers late April to early May, fruits mature in fall, and are deciduous. They both have 4-petaled white flowers, similar-shaped leaves. The white petals of dogwood flowers are in fact bracts, not petals; the true flowers are yellow to green clustered in the center. Dogwood fruits will cluster but are red when mature.

Left: Flowering dogwood by kemper, iNaturlist; Right: Dogwood leaves and flowers by cairn

Dogwood leaves can be bright green like jet bead, but dogwood leaves are entire and may look glossy; the underside is hairless.

How to look for Jetbead
Jetbead is easily identifiable due to its distinct leaves, flowers, and fruits. Alex was able to see it from across the road while we were driving by the National Zoo. I’ve seen it countlessly during hikes along the trails, especially where water is close by. According to Rawlins et al. (2018) and Swearingen & Fulton (2022), Rhodotypos does best in sunny areas with moist, rich soils, but can adapt to disturbed and polluted areas, shade, and different types of soils and pH. Here in the mid-Atlantic, you can find it in “forest interiors” (Swearingen & Fulton, 2022).

Tips for making a good observation
Take photographs that show:
the landscape around the plant – this shows the context and offers a clue to the scale of the
infestation
if they are flowering, photograph a whole plant including flowers and leaves
if they aren’t flowering yet, photograph a whole, typical, undamaged leaf.
with jetbead, you should be able to find some fruits as well.

Make comments that:
are explicit about the issue of intentional plant vs weed vs escaped (You’d be surprised but
some parks include intentionally planted alien plants which are now invasive – life is
complicated!)
give a rough estimate of the number of patches and the area covered
any other comments you think might be helpful
 

Have you seen evergreen, parsley-like leaves on the forest floor? They may be the evergreen winter foliage of plants in the genus Corydalis. Only two species are known to occur in our area: one is native (Yellow or pale fumewort, Corydalis flavula) and the other invasive (Incised fumewort, Corydalis incisa). The alien was reviewed by USDA APHIS in 2017 and they concluded that this is a “high risk” invader, which means that it has both the potential to become widespread and the potential to cause a lot of damage.

These facts are from the APHIS assessment:

“As demonstrated by its status in the United States, C. incisa exhibits a strong ability to escape and spread. It is a shade-tolerant (Fleming, 2017; Glick, 2017b) annual/biennial (Zhang et al., 2008) that is self-compatible (Zhang et al., 2009) and has a high reproductive capacity (Nakanishi, 1994). Plants ballistically eject seeds out of the fruit pods up to three meters away (Nakanishi, 1994). Seeds can then be further dispersed by either ants (Andruk, 2017; Zhang et al., 2008) or water (Atha et al., 2016a). U.S. evidence indicates that plants are likely being dispersed as contaminants in nursery material (Maurer, 2017). Plants can form dense patches and seem tolerant to hand-pulling and clipping at certain stages of their life cycle [Atha et al., 2016a; Atha et al., 2014b; Andruk, Hudson, and Nolan, unpublished data (provided by Andruk, 2017)].”

How to Identify During Bloom:

Flowering begins in March, and at that time the species are easy to tell apart by flower color. The alien (Incised fumewort) is purple, and the native (Yellow or pale fumewort) is yellow. Plants produce mature seeds quickly, within two or three weeks of first bloom.

Commons Incised Fumewort (C. incisa) can grow 10-50cm tall and has purple flowers. Photograph of Corydalis incisa by KENPEI, CC BY-SA 3.0, via Wikimedia.

Yellow or Pale Fumewort (C. flavula) can grow 15-30cm tall and has yellow flowers. Photograph of Corydalis flavula by Fritz Flohr Reynolds, CC BY-SA 3.0, via Wikimedia.

How to Identify Before Bloom:

Flowers are not always present so it can be handy to know how to identify Corydalis species from just their leaves. This can be especially handy in winter because these species are evergreen! In winter, petioles emerge directly from the root crown. In the illustration below, we see two petioles, each holding one leaf. The petiole splits into thirds, each sub-petiole supporting a leaflet. Leaves that split into three parts are called ternate, and the most familiar example of a ternate leaf would be clover. In the illustration, the terminal leaflet is shaded. On top of that, each leaflet is divided into three sub-leaflets (dark green shading). In the alien species, some of these sub-leaflets are divided (all the way down to the vein) yet again. In the native species the sub-leaflets are lobed, sometimes deeply lobed, but not divided. The most reliable trick I can recommend for telling these two species apart (when flowers are absent) is to count the lobe tips on a sub-leaflet. The native species will have something like 5 to 7, and the alien will have two or three times that. Look at the illustration and count the tips on the sub-leaflets and see what numbers you come up with!

Line drawing of the two types of leaves by Sara Tangren, National Capital PRISM, CC BY.

Looking at a tangle of leaves on the woodland floor, or in an iNaturalist photo, the individual leaves can be hard to discern. The key to success is to isolate an individual leaf so that you can get a good look at its outline. Check out the observations by izafarr and sara_tangren. Can you confirm these identifications based on the photos?

Photograph of C. incisa leaves by izafaar, CC BY-NC, via iNaturalist.

Photograph of C. flavula leaves by sara_tangreen, CC BY-NC-SA, via iNaturalist.

There are also some qualitative differences between the two types of leaves, but unless you have them side by side, it’s hard to use qualitative differences for identification. For example, in winter, the alien leaves tend to be darker, but sometimes lighter toward the center, and they tend to have little white spots on them (glands perhaps?). These differences are useful but gradational, somewhat inconsistent from plant to plant, and fade as winter moves into spring.

Tips for making a good observation record of Corydalis:

Take photographs that show:

• the landscape around the plant – this shows the context and offers a clue to the scale of the infestation
• if they are flowering, show a whole plant including flowers and leaves
• if they aren’t flowering yet, show a whole, typical, undamaged leaf

Make comments that:

• are explicit about the issue of intentional plant vs weed vs escaped (this saves reviewers a few minutes checking for cues of cultivation in the photo and zooming in on the map)
• give a rough estimate of the number of patches and/or the area covered
• any other comments you think might be helpful

Similar Species:

Yet another purplish-flowered member of the poppy family has been detected in our area, Common fumitory (Fumaria officianalis), but it’s quite different looking. It tends toward somewhat sunnier habitats, is a taller plant, and stands weakly erect. It blooms later in spring to early summer. If you look closely at the leaves you’ll see the “family resemblance”.

Common fumitory (F. officianalis) can grow 10-50cm tall and has purple or crimson-tipped, pink flowers. The leaves are alternate, compound, and lobed. Photograph of Fumaria officinalis by Llez, CC BY-SA 3.0, via Wikimedia.

There is another purplish-flowered woodland Corydalis invading to our north, bird-in-a-busch (C. solida). As the name implies, the leaves are not so thoroughly divided. There’s a nice photo of it in its native range here. Although I have read that it is not expected to range this far south, I notice that the iNaturalist map shows reports all throughout Europe. Perhaps it would be best to keep an eye out!

Bird-in-a-bush (C. solida) can grow up to 25 cm and has blue-purple, pink-red, or purplish-red flowers. The leaves are alternate, compound, and lobed. Photograph of Corydalis solida by Jean-Pol GRANDMONT, CC BY-SA 3.0, via Wikimedia.

I suspect a few of you know more about the fumeworts than I do. I’d sure appreciate any corrections and additional insights. Happy hunting!

Our mission is to change the very nature of the fight against alien-species invasion. What has happened historically is that when an alien species first arrives, very few people notice it. Only once a species is so widespread that the damage is intolerable is there sufficient public support to mount a response. But by then eradication is no longer feasible, and even management just to keep populations at acceptable levels is extremely expensive and/or labor intensive. The current process is lengthy and ineffective.

By working with citizen scientists like yourself, we can increase our chances of detecting an alien species shortly after it arrives in our region. We can then mobilize to remove the species using minimal public resources. For example, in the case of a new infestation that consists of only a few plants, a single authorized person could be dispatched to eradicate the infestation by hand in only a few minutes. This process is fast and effective.
As an iNaturalist participant, you can help by making reports of target species whenever you see them in the National Capital Region. If you would like to become even more involved, contact me to learn more about the Invader Detectives program. Our short training presentation includes species identification, tips for making the most effective observation reports, and how to help by becoming a verifier.

Sincerely,
Sara Tangren, Coordinator
National Capital PRISM
sara.tangren@dc.gov