March 31, 2024

Identification "expertise"

I've been thrilled to be invited as a validator to iNaturalist's experiments to estimate the accuracy of observation IDs (v0.1, v0.2, v0.3). There has been a lot of discussion in the comments sections on the corresponding blog posts on how to determine whether someone is qualified to validate identifications on iNaturalist. (The details on how this was done are in the methods sections for each experiment.)

There have been suggestions to leave it to the "local/taxon experts" which has me wondering: Where and what am I focusing on when identifying on iNaturalist? So this journal entry is just here to illustrate that and collate a few links and resources for future reference. Firstly, let me confess that I'm not an expert on anything. I'm just someone who got hooked on doing identifications on iNaturalist. It's sort of my way to virtually "go for a walk" when I need to decompress and do something hopefully useful for others while doing so. I also find that I'm learning a ton while doing this. There may be some older IDs out there that I made early on in this learning process, so don't hesitate to ask or correct me if you come across one of my IDs that seems wrong.

I found the best overview of where people focus their identifications is using the identifications heat map. To get your own, use this URL and replace my user name with yours:
https://www.inaturalist.org/observations/map?ident_user_id=annkatrinrose#2/0/0

Here's a snapshot of my identifications as of March 2024:

A couple of things to note:
1) Obviously my hotspot is in the Southern Appalachian Mountains. This is where I do most of my identifications and feel most comfortable claiming I know a few things. I still keep discovering stuff new to me though.
2) The secondary hotspot in Denmark is coming from sorting out unknowns over there a while back when that country was a hotspot for unknowns. I don't think it is quite that hotspot any more, and I'm not really an expert in that area.
3) Most of the IDs I made in Africa were coarse IDs of plants to angiosperm, dicot, or monocot for the purpose of annotating phenology (which is not available on Plantae).
4) A lot of my IDs scattered around the globe outside of the areas mentioned above are for cultivated Venus flytraps. I don't really know much, if anything, about the local flora in these places.

Another indicator for "expertise" might be what taxa someone specializes on. I'm not really a specialist on anything in particular, but I do way more plant identifications than anything else. The following is a screenshot of my current (March 2024) top taxa identified. The ones marked in green were also on a top 10 list I made in November 2022, and the red one indicates the top cultivated one (not surprisingly the aforementioned Venus flytraps).

I use my "favorites" list to keep a record of the taxa for which I found myself to be either the top observer or top identifier, so that is another place to check to see what I've been interested in or focused on. I've occasionally used links posted on the forum to get my data for identification species counts and observation species counts. (To get your own, follow the links and replace my user name in the URL with yours.) I found these useful to check my counts against the overall counts to find likely candidates for which I might be the top identifier/observer.

Posted on March 31, 2024 01:37 PM by annkatrinrose annkatrinrose | 1 comment | Leave a comment

December 20, 2023

Titan arum bloom at Appalachian State University

Maybe inspired by Halloween, Mongo the resident corpse flower (aka titan arum, Amorphophallus titanum) at the Biology Greenhouse at Appalachian State University sent up a flower bud for its first bloom in early November this year. It took over a decade to grow to this stage from a fist-sized corm received as a gift from the Atlanta Botanical Garden. After teasing us for a while with a bit of stop-and-grow (probably responding to light conditions), it finally blossomed the day after Thanksgiving. Pictures and a timeline of the bloom progression are available on Mongo's website.


Mongo in all its smelly glory shortly after midnight in the early morning hours of Nov. 25, 2023. It grew to a little over four feet tall.

This plant species is famous for making the largest unbranched inflorescence known and is endangered in the wild with fewer than a thousand individuals left in its native range on Sumatra. Being such a prominent record holder in the plant kingdom, it is however a flagship species for botanic gardens and cultivated around the world. As a tropical rainforest plant of sizable stature, it is not suitable as a houseplant though and its cultivation requires a greenhouse facility that can accommodate its high temperature and humidity needs. It takes a decade or longer to grow from seed to blooming plant, and once it reaches maturity it will bloom only for a few days every couple of years. Every one of these blooms attracts a crowd of admirers. An estimated 3,000 people turned out to see (and smell) this botanical marvel up close and personal at AppState. Almost everyone took pictures, but curiously I'm the only one who has uploaded any on iNaturalist. Well, I tried to make up for it by uploading nearly a dozen observations to cover this event. I hope y'all forgive my botanical nerdiness! (It also taught iNat that this plant is cultivated in this location, so any future uploads should be automatically marked not wild.)


Botanist delight - not sure what was more exciting: Mongo's bloom or seeing how many people showed up and waited in line in the freezing cold for up to an hour just to see a plant!


Great to see so many youngsters get excited about a stinky flower. Mongo had fans coming back several times. Great pictures, I'd say!

Being a family member of the Araceae, the inflorescence takes the shape of a spadix (central column) with a surrounding spathe (frilly skirt). It produces both warmth and stench to attract its pollinators (flies and carrion beetles) by mimicking the looks and smell of something dead and decomposing, hence its nickname corpse flower. Its distinctive odor is said to be the strongest in the early morning hours of the day of its bloom. Having personally witnessed the bloom and talked to our greenhouse manager, who came in just as I was leaving after midnight, Mongo was at its stinkiest around 1-2 AM after the spathe unfurled. I thought it smelled more fishy than rotting meat. The smell does linger - I felt I kept smelling it for days, possibly hanging onto my clothes or maybe just my imagination.


We did have a few interested costumers checking things out. Hidden inside the vase-like spathe at the very base of the spadix are the actual flowers, a ring of males with stamens on the top and another ring of females with carpels below.


Our greenhouse manager cut a window into the base of the spathe to open up a view inside. The female flowers are the purple-reddish pegs on the bottom and the male flowers are the yellow bumps on the top.

The plant prevents self-pollination by maturing its female flowers during the first day while oozing the pollinator-attracting stench. The male flowers will release their pollen strands a day later once the females are no longer receptive to pollination. We tried to acquire pollen but were unsuccessful. Apparently it requires high humidity to mature, and cutting a window as well as opening and closing the door as visitors came through probably prevented the conditions to be right for pollen release. We did take a few samples for microscopy.


Removing some florets to preserve in glutaraldehyde for microscopy.

Now we may have to wait for another couple of years for the next opportunity. Given the proper care, it should be even bigger and smellier than this first bloom!

Posted on December 20, 2023 01:29 AM by annkatrinrose annkatrinrose | 12 observations | 2 comments | Leave a comment

September 24, 2023

NC campus BioBlitz this week

Hello friends and followers!

It's that time again: The next NC inter-campus Nature Challenge is happening this coming week. Appalachian State University, UNC Greensboro, and UNC Wilmington will be facing off against each other again to see whose students can find the most wildlife on campus during the week.

Anyone can participate, either as an observer or as an identifier. Observations have to be of wild organisms, made on university properties, and during the week of Sep. 25 - Oct. 1, 2023. You can join the AppState BioBlitz project if you want, or use it to filter for observations that need IDs to help us out! (I'm sure the other universities would appreciate some help, too, especially with IDs.)

I expect a good number of first-time iNat users and there will be prizes to win and extra credit to earn. I will try to keep an eye on things, but any help with IDs and marking things cultivated that aren't wild would be very much appreciated!

To make it easier to sort out the planted from the wild, I've created an AppState Tree and Shrub Inventory project for the cultivated stuff. Feel free to check that out to see what species have been previously observed planted around campus. (If you are exploring that project, remember to uncheck "verifiable" or nothing will show up since everything in it is casual.)

Posted on September 24, 2023 05:22 PM by annkatrinrose annkatrinrose | 0 comments | Leave a comment

April 17, 2023

NC BioBlitz this week

Hello followers, just a heads-up that this week is BioBlitz week in NC. This spring three universities (Appalachian State University, UNC Greensboro, and UNC Wilmington) are heading off against each other in a friendly competition to see who has the greatest biodiversity on campus. If you're in the area, feel free to join our project at Appalachian State University and participate!

Even if you are not around to make observations, any help with IDs and marking things cultivated that aren't wild would still be very much appreciated! I predict lots of new iNat users and casual observations across all three campuses. Here is the Campus Nature Challenge project if you want to check all three schools at the same time.

Posted on April 17, 2023 04:04 PM by annkatrinrose annkatrinrose | 0 comments | Leave a comment

December 13, 2022

Monarch Annotation Project

While we're finishing out fall semester, I'm starting to plan what to do with my students in spring. I'd love to incorporate iNaturalist into class somehow, but spring is a challenging season for observations (winter weather keeping a lot of plants and critters dormant until shortly before finals). So I've been thinking about annotation projects that can be done with already existing observations that would also work as a homework assignment or snow day activity. So far, I've come up with this list of guidelines for such projects:

  • make use of observations already uploaded to iNat
  • suitable for beginners (no steep learning curve)
  • don't require students to make identifications
  • have a reasonable time limit (e.g. 3 hours to gather data)
  • could be split up to work as group projects for student teams
  • obtain results for discussion and further analysis

I like to try things out before using them in class, so I figured I would give the assignment to myself and pretend to be a student. Since I plan on focusing on phenology annotations in my Botany course, I wanted to pick something as a "pilot project" that isn't necessarily plant-focused to avoid basically doing the homework for my students. I want them to get curious about plants and design a cool project that they can own! Therefore, I picked the monarch butterfly for a proof-of-concept study and decided to annotate life stages. I think this is very similar to looking at plant phenology as it should be just as easy for a student to recognize e.g. a plant in bloom as it would be to tell butterflies and caterpillars apart. Additionally, it is a very iconic and easily recognized creature that gets ID'd very quickly and accurately by the community.

To demonstrate their understanding of the scientific method, students should start with a question to provide the motivation for collecting data. In my case of the monarchs, I've been curious for a while how their appearance here in the mountains compares to other places off the mountains. I rarely see any before mid summer. Why is that? My hypothesis was that the monarchs coming up from Mexico in spring avoid the colder mountains at first, but then later show up here to breed over the summer before the fall migration back south. Based on this, I would predict a lack of adult monarchs in the mountains in spring, but a bump of caterpillars for late summer and a bump for the adults migrating through in fall. The objective was to annotate life stages throughout the year across several locations to be able to test this hypothesis and compare the data between mountain and non-mountain areas.

I started with annotating life stages (egg, larva = caterpillar, pupa = chrysalis, adult = butterfly) for NC observations and indeed found a low number of butterflies in spring compared to summer and fall. Not quite content yet, I expanded west to include three more states crossing the migration path around the same latitude - Tennessee, Arkansas, and Oklahoma. I decided to stick with the same latitude since decreasing day-length is a major trigger for the migration in fall. Adding annotations for these took a couple of hours, but I think for a team of four students this would still be within the scope of time investment for a lab class project by splitting up the work to have each student tackle annotations for one state. I then took screenshots of the graphs for the annual distribution of life stages for all four states and used PowerPoint to create a summary of the results.


Monarch life cycle stages observed across the year for the states of Oklahoma, Arkansas, Tennessee, and North Carolina. NC is further split into Mountains, Piedmont, and Coastal Plain. Graphs on top of each other were adjusted in height to match the scales on the Y-axis for comparison across states and NC regions. (Note: I did not pay attention to scale the graphs for the regions to the states as well.) Vertical lines indicate peak observation times of butterflies in April, August, and October.

So the big question: Did this result in something interesting to discuss in class? You bet! Look at that neat bump of migrating butterflies in April in OK and AR that's basically missing in TN and NC. The 'central flyway hypothesis' for spring migration confirmed! Then there's a bump in adults showing up in August in NC, TN, and to some extent even AR, that's completely missing in OK, lending support to the idea of an eastward migration of butterflies into and across the Southern Appalachian Mountains in summer. Numbers peak again in October, consistent with the fall migration south.

Students could search for literature to expand the discussion, e.g. comparison with publications based on citizen science data from Journey North (two flyways revealed), or the study by Miller et al. that found monarchs crossing the Appalachians to the east coast in early July north of the area annotated here. One follow-up question to ask could be whether the bump in August in NC/TN represents monarchs raised locally or coming from the west or south or maybe even north. Students could suggest experiments that could be done, informed by the studies listed above and the Monarch Watch tagging program.

Additionally, there's the opportunity to discuss observer bias in citizen science projects. E.g. one would expect more monarchs migrating in fall through OK and AR than NC, yet the peak is higher in NC. How come? Are there more observers in NC than OK? Closer inspection of the observations in question reveals that there are a good number of fall roosts with dozens or even hundreds of butterflies observed in the Midwest, but basically none of those in NC. Therefore, the number of observations underestimates the total number of butterflies being observed in Oklahoma during October. Further, eggs and caterpillars are likely under-observed in general due to the difficulty in finding these to make observations in the first place.

One thing that might prove challenging from an instructor perspective is the difficulty of keeping track of annotations to confirm that students are doing their homework, and providing quality control for those from the teacher side. Unlike for identifications with leader boards for species and locations, there are no stats available for annotations. I haven't found a way yet to search for annotations made by a particular user/student. Maybe there is a URL hack for this, but I haven't been able to figure it out yet. Currently, I'm thinking of having the students summarize their results in the form of a term paper listing exactly what they did on iNat in the methods so I can follow up on it. There is also no way currently to correct a wrong annotation (there's a feature request) short of messaging the observer and/or annotator, as I think those are the only two people who could remove an annotation made in error. I don't think iNat notifies you when someone annotates your observations, so a lot of errors are probably not even getting noticed.

Overall, I'm pretty excited about the possibilities here and look forward to seeing what projects my students will come up with. I think the annotation features on iNat are still way underused and could be a neat way to have students engage with observations of interest to them and add value to iNaturalist by adding or improving data.

Posted on December 13, 2022 09:17 PM by annkatrinrose annkatrinrose | 2 comments | Leave a comment

December 08, 2022

Fairies, Unicorns, and Playing Devil's Advocate

Every now and then, someone will revive the discussion on the iNaturalist forum about the supposed uselessness of the male/female annotation option for plants. They aren't common but they are out there! Botanically speaking, these plant species are dioecious meaning male and female reproductive structures are present on separate individuals. So let me present a compelling case of using the male and female annotation for plants for citizen science.

Meet the fairywand, Chamaelirium luteum, also known as devil's bit, false unicorn, blazing-star, and helonias (all very confusing common names as they are shared with other plants). Its range extends over much of Eastern North America all the way from parts of New England and Canada down to Florida and west to Arkansas. A long-lived perennial, it takes about 5-7 years for a seed-grown plant to reach flowering age. The plants grow as basal rosettes of leaves with about 10-20% of the population bolting with tall flower stalks blooming in spring. As you might suspect already, this species is dioecious with male plants making staminate flowers only and female plants making pistillate flowers only. Interestingly, these male and female flowering plants are not evenly distributed but show a generally male-biased sex ratio. Why is that?


Chamaelirium luteum morphology, based on Britton & Brown's Illustrated Flora (public domain) and iNaturalist observation photo of a male (left) and female (right) plant (Milo Pyne, Creative Commons).

The sex distribution in this species was studied by Thomas Meagher at Duke University, NC, and summarized in several papers published in the early 1980s. The first study reported on the spatial distribution of males and females at four different study sites in North Carolina over the span of six years and found that plants of each sex tend to cluster together in same sex groupings with males usually closer to each other while females tend to grow more isolated (PDF). The second part of the study then took a closer look at the sex ratios at different developmental stages from seedlings to adults. While propagated seedlings started out with near equal representation of both sexes, flowering plants were found to show a significant bias with on average 3.5x as many males as females (PDF).

A third study classified the plants into three groups, juveniles of unknown sex, males, and females, and took a closer look at the possible explanations for the observed gender bias. It found differences in mortality rates with seedlings having the highest mortality rate, followed by juveniles and then females before males. Males started to flower at a younger age compared to females, and females grew consistently taller flower stalks with more cauline leaves then males, followed by a reduction in plant size the following year suggesting a higher reproductive cost of flowering and fruiting for females. While males were able to flower in subsequent years with some individuals blooming for every year of the study, females flowered at most every other year. (Unfortunately, this article is not freely available as a PDF but you can get it from Wiley or JSTOR.)

Having read about the sex ratio bias in this species, I was curious whether that was something that would show up in iNaturalist observations as well. So I set out on a little annotation project, marking male and female plants in the Southern Appalachian Mountains (to limit time investment). Overall, iNaturalist observations show a good overlap with the range map for this species on BONAP (the outlier in New Hampshire is a rosette of leaves that looks to be something else misidentified as this species).


Observations of Chamaelirium luteum recorded on iNaturalist (left) compared against the distribution map from BONAP. The yellow shaded area represents the "Southern Appalachian Mountains" place boundary on iNaturalist.

There are no sex chromosomes so the only way to distinguish between male and female plants is by flower morphology. Fortunately, this is fairly straight-forward on typical iNaturalist pictures due to the sexual dimorphism of the flowers as shown in the images below.


Comparison between male (left) and female (right) flowers of Chamaelirium luteum, using a collage of Creative Commons licensed pictures from iNaturalist observations. Male flowers can be recognized by the presence of anthers atop six stamens, while female flowers have a three-parted stigma leading to a swelling ovary that eventually turns into the seed capsule. Both male and female flowers have six white, linear petals surrounding their reproductive parts.

So what's the verdict? I think the case is pretty clear: iNaturalist observations support that there is a sex ratio bias towards more males than females. As reported in the papers above, peak bloom time was in May, which also coincided with peak observation time on iNaturalist. I only annotated flowering and fruiting plants (155 or ~69% of 226 RG observations in May; most of the remaining plants showed rosettes of leaves with no flowers) that were clearly identifiable as either male (128 observations or ~83%) or female (9 observations or less than 1%) for a bias of a whopping 14x more males than females observed at peak bloom. I was undecided about the sex on 18 (~12%) flowering observations, mostly due to the photos being too far away or too blurry to see the necessary details, but even assuming that these plants are females the gender bias is still pretty clear.


Phenology (A) and sex (B) distribution data for Chamaelirium luteum observations in the Southern Appalachian Mountains.

And now that I've successfully procrastinated until midnight, I've got to get ready for final exams tomorrow... o_o (Fortunately, I'm the instructor, not a student, haha!)

Posted on December 08, 2022 05:21 AM by annkatrinrose annkatrinrose | 2 comments | Leave a comment

November 08, 2022

Appalachian snakeroot identification resources

Not too long ago (earlier this year?), iNaturalist started recognizing Appalachian snakeroot (Ageratina roanensis) as a species rather than a variety of A. altissima. Prior to this, many of these plants were identified to Research Grade under A. altissima with only few being narrowed down to variety. I know I have contributed to this as I rarely ID to variety or subspecies, and as far as I can tell nobody has revisited these observations yet to see if they need updating. Since there aren't enough observations identified to A. roanensis yet (77) to qualify for inclusion in the Computer Vision training set, iNat CV consistently suggests A. altissima for all of them, further adding to the pool of potentially misidentified plants. The purpose of this post is to summarize a couple of resources that might help with sorting them out.

Distribution and Habitat:
A. roanensis appears to be a Southern Appalachian endemic found in the mountainous areas of Alabama, Georgia, Kentucky, North Carolina, South Carolina, Tennessee, Virginia, and West Virginia, and primarily at elevations above ~4,000 ft. Its typical habitat is moist to mesic northern hardwood forests and spruce-fir forests.

Distinguishing Characters:

  • Leaves: The leaf blades tend to be more deltoid (triangular) in shape compared to more ovate in A. altissima, and the leaf base is said to be generally subcordate or truncate vs. generally broadly cuneate. However, I see a lot of overlap and I'm not confident I could tell them apart for sure just based on leaf shape.
  • Inflorescences: These are said to be arranged in more dense corymbs in A. roanensis vs. more open corymbs in A. altissima. A. roanensis has more florets per head (18-34) compared to A. altissima (9-20). This can be hard to see on the typical iNat photographs - I find it easiest to count if the individual flowers haven't opened up yet. Again, there appears to be quite a bit of overlap with Weakley suggesting A. r. can go as low as 15 florets and A. a. can show up to 25 florets. Another difference is the length of the phyllaries with 5-7 mm in A. roanensis vs. 3-5 mm in A. altissima.

If anyone knows of other features that can be used to distinguish them, and in particular how to tell them apart on the typical iNat-quality photographs, please feel free to add those tips in the comments below!

References:

Posted on November 08, 2022 12:49 PM by annkatrinrose annkatrinrose | 6 comments | Leave a comment

October 21, 2022

NC BioBlitz next week!

UNC Greensboro and Appalachian State University will have their first BioBlitz competition happening next week. Guess who volunteered to help organize this? Can't say no to a challenge involving iNaturalist, right? Of course I got involved with this, and now I'm going to try to get all my followers involved too! :-)

Anyone can participate, either as an observer or as an identifier. Observations have to be of wild organisms, made on university properties, and during the week of Oct. 24-Oct. 30, 2022. You can join the AppState BioBlitz 2022 project if you want, or use it to filter for observations that need IDs to help us out!

There will be prizes to win, extra credit to earn, and a lot of iNat newbies interacting with the platform for the first time. I will try to keep an eye on things, but if you notice any irregularities or problems arising from this BioBlitz event (e.g. a bunch of obviously planted stuff not marked cultivated or nonsense IDs being added), please feel free to let me know and I can do some quality control and communicate with faculty and students involved.

Posted on October 21, 2022 11:17 PM by annkatrinrose annkatrinrose | 0 comments | Leave a comment

October 09, 2022

Almost there: Help beaked dodder qualify for CV inclusion!

Every now and then I come across a species that should be fairly easy to identify, but there aren't enough confirmed sightings yet on iNaturalist for it to be included in the computer vision (CV) training set. One such species is beaked dodder (Cuscuta rostrata, currently 73 observations total).

Yes, I can see those of you familiar with dodder raise an eyebrow at the assertion that this is easy to ID (most dodders are anything but and community ID stays at genus level). However, this one is! If you come across this plant while hiking in the woods and know what to focus on, you can get a picture that allows for positive ID, and if you see this feature on photos on iNaturalist within the correct range you can quite confidently identify it.

The feature in question is a beak-like extension of the ovary that gives the plant one of its common names beaked dodder. Other dodders growing within its range (e.g. the otherwise very similar C. gronovii) do not have this type of beak on their round ovaries. Another feature that works in the field is to smell the flowers - this dodder species is said to have a very fragrant smell. The combination of correct range + fragrance + beak makes for a slam-dunk botanical ID that is sure to impress all your naturalist buddies!

Where to look for it:
This species is a Southern Appalachian endemic and occurs mostly in high elevation hardwood forests from West Virginia south to northeast Georgia. It likes shady areas (I've found it growing in seepage areas in deep shade) but may also be found in more open places like grassy balds. (The similar C. gronovii is essentially a wetland species, often found along stream margins and in marshes and wet fields.)

Host plants:
It does seem to have a wide range of host plants that it can latch onto. Numerous herbaceous species (I've seen it on Rudbeckia, Monarda, and Impatiens, for example) and a few woody species (Rubus, Hydrangea) appear to be preferred hosts. It can be grown on Coleus in cultivation, if anyone is so inclined.

Posted on October 09, 2022 06:24 PM by annkatrinrose annkatrinrose | 3 comments | Leave a comment

December 03, 2021

White-flowered stonecrops of eastern North America

If you trust iNat's ID suggestions, then there's only one white-flowered stonecrop in the eastern US, Sedum ternatum. However, as anyone familiar with the pitfalls of computer suggestions might guess already, there are actually more than that. One in particular, Sedum glaucophyllum, is frequently misidentified as S. ternatum but tantalizingly close to having enough observations to be included in the next computer vision model. This post is intended to raise awareness of its existence and provide a comparison and guidance how to tell the two species apart.

I first encountered S. glaucophyllum on iNat while reviewing observations for S. ternatum and noticing different leaf arrangements than the plants I was familiar with. Almost at the same time, I was made aware of the existence of S. nevii through a plant give-away at the NC Native Plant Society. This made me look into these additional species a little bit more. Both have white flowers very similar to S. ternatum and neither of them are "known" by the current computer vision model.

Sedum Comparison
Botanical drawings of S. ternatum and S. nevii from Britton, N.L., and A. Brown, 1913, An illustrated flora of the northern United States, Canada and the British Possessions. Note the leaves in whorls of three on S. ternatum sterile shoots and opposite or whorled on flowering shoots as compared to leaves in spirals on sterile shoots of S. nevii with alternate leaf arrangement on the flowering shoots. S. glaucophyllum was split from S. nevii later and therefore did not have a separate drawing in this publication. However, it is similar in appearance but more variable and typically a little larger than S. nevii.

Both S. glaucophyllum and S. nevii are much rarer finds than the common woodland stonecrop and more specialized in their habitat. A glance at their distribution maps shows that both overlap with S. ternatum but are more restricted in their range and do no overlap with each other. S. glaucophyllum is endemic to Virginia and West Virginia with a few isolated occurrences in North Carolina and Maryland, while S. nevii is mostly found in Alabama with some populations in Tennessee and Georgia. S. glaucophyllum is found in cracks on cliffs and rocky habitats with moderately high pH soil and is absent in acidic rock outcrops. S. nevii grows in shallow, gravelly soils on steep bluffs of gneiss, an acidic, granite-like rock.

Sedum distribution map
Distribution of Sedum ternatum, S. glaucophyllum, and S. nevii in the Eastern US based on BONAP data to color in the distribution for each plant.

Since the current ranges of S. nevii and S. glaucophyllum do not overlap, location should be a clue for identifying these if found growing wild. (However, both species may be used as garden plants beyond their native range.) Digging a little deeper, it appears S. glaucophyllum differs from the other two species by chromosome count. While S. nevii always has 6 chromosome pairs and S. ternatum has 8, S. glaucophyllum shows 14 chromosomes or more, suggesting that it may have originated as an allopolyploid of the other two species.

It should be mentioned that there is one more species of white-flowered Sedum present in the eastern US, S. pusillum. However, this species is more similar to the elf orpine, Diamorpha smallii, currently included in the CV model and therefore more likely to be confused with that species than with S. ternatum. It is restricted to granite outcrops from Anson County, NC, to southwestern Georgia.

Posted on December 03, 2021 05:41 AM by annkatrinrose annkatrinrose | 3 comments | Leave a comment