Αρχεία Ημερολογίου για Οκτώβριος 2020

Οκτώβριος 01, 2020

NYBG EcoFlora October EcoQuest Challenge


Common Mugwort (Artemisia vulgaris) is a Eurasian perennial in the Sunflower family (Asteraceae). Multiple introductions to North America beginning in the 1600s and subsequent genetic crossing have resulted in a range of morphological diversity, especially in leaf form. Outside its native range it is highly invasive, spreading by seed and underground rhizomes and forming monocultures.

How many Common Mugwort can you find by October 31?

Follow projects stats

Posted on Οκτώβριος 01, 2020 0857 ΜΜ by danielatha danielatha | 3σχόλια | Αφήστε ένα σχόλιο

Οκτώβριος 20, 2020

The Case for Recognizing Persicaria amphibia and Persicaria coccinea as Distinct Species

Daniel Atha, revised October 20, 2023


I am inspired by the beauty and ecological importance of these plants and motivated by a desire to protect them from further degradation. That’s why I posted this extended explanation and include a link along with my identifications. Thank you for taking the time to read it.

My interest in Persicaria began over a decade ago when I found a Smartweed plant (Persicaria extremiorientalis) right outside my office door and all over New York City that had been in North America for fifty years, yet was unrecognized by all botanists, including Arthur Cronquist, one of the most famous botanists of the twentieth century. who wrote the flora of the northeastern United States and had an office in the same building (although not at the same time. Unfortunately he passed away the year before I arrived).

I've collected hundreds of Persicaria specimens and examined thousands more in major herbaria. I have studied the literature old and new, published papers of my own, been a peer-reviewer for journals and corresponded with the handful of Polygonaceae specialists practicing today. I know the North American species pretty well and can recognize most from photographs. The plants are gradually making me smarter and since 2010, I've discovered two additional species new to North America (Persicaria hispida and Persicaria posumbu).

The Amphibious Smartweeds, Persicaria amphibia and Persicaria coccinea attracted my attention early on because they are such beautiful plants, yet no one seemed interested in them, perhaps because of their tortured taxonomic history. The more I learned about them and the sorry state of our professional conclusions, the more I wanted to “understand” them and reveal their unique qualities and relationships to each other and their surroundings.

Figure 1. Water Smartweed, Persicaria amphibia var. stipulacea (Photo 160158626, (c) Ian Guthrie, some rights reserved (CC BY-NC), uploaded by Ian Guthrie). Is it an exaggeration to say this is one of the most beautiful plants there is? The wonderful photo helps us see it.

Figure 2. Scarlet Smartweed aka Longroot Smartweed, Persicaria coccinea (Photo 298785464, (c) Ocean, some rights reserved (CC BY-NC), uploaded by Ocean). This is another spectacular photo that captures the essence of the plants with superb aesthetic qualities such as light, texture, color, form, movement, balance and composition.

Smartweeds are a genus of about 100 species primarily of the north temperate zone of both hemispheres. Most species are annuals with simple, alternate, entire, ovate or elliptic leaves and spicate inflorescences with small, five-parted flowers. Hybridization, introgression and polyploidy are especially common in the core “Eupersicaria” group of the genus. There are few autapomorphies (unique derived traits) that clearly distinguish one species from another. Often a suite of characters are necessary to define a species and distinguish it from others. In addition, the species can be quite variable and morphologically plastic in response to environmental conditions, especially periodic inundation (as are the two species discussed here). The Pale Smartweed Persicaria lapathifolia, Lady’s Thumb Persicaria maculosa and Persicaria densiflora can also form inflated, floating stems when flooded.

Persicaria amphibia var. stipulacea and Persicaria coccinea (Persicaria amphibia var. emersa) are perennial North American natives that inhabit high-quality, oligotrophic and mesotrophic wetlands, especially the OBL oligotrophic Persicaria amphibia var. stipulacea. They are both adapted to fluctuating water levels (hence the “amphibious” epithet). Persicaria amphibia (sensu stricto) is normally an aquatic with floating leaves, but when stranded on dry banks can grow aerial shoots (with often with flared ocreae). Persicaria coccinea is normally a palustrine species with aerial shoots, but can tolerate temporary flooding and may sometimes develop floating stems and leaves, but never flared ocreae.

The two species are treated as varieties in the current iNaturalist classification, strictly adhering to Plants of the World Online (POWO), which itself follows the influential opinion of Richard Mitchell (1968) who did his dissertation research on these plants. Recognition at the varietal level is far better than just one heterogeneous species (as Persicaria amphibia) advocated by Mitchell, but still short of the two species classification widely accepted before 1968 and suggested by the evidence presented here.

How we recognize these taxa is of critical conservation concern. Species of Persicaria are an important source of food for wildlife, especially waterfowl which share the same habitat and consume large quantities of the seeds. Persicaria amphibia and Persicaria coccinea often occur in extensive, dense populations and are primary producers, cycling nutrients and supplying food and habitat for macro- and micro- invertebrates as well as vertebrates (Partridge, 2001).

The vast majority of specimens and observations across North America will key out clearly with the key below. But there are populations that don’t, especially in the mountain west. These anomalies may be genetic mixtures from hybridization and introgression, both phenomena common and well-documented in the genus. Each species’ extreme anatomical plasticity and the existence of intermediate specimens has thrown botanists into taxonomic fits for 200+ years, lumping the entire range into one artificial super-species (e.g., R. Mitchell) or dividing every minor morphotype into a separate species (e.g., E.L. Greene).

Persicaria amphibia is a circum- boreal and -temperate species occurring in America, Asia and Europe. It has long been recognized that the American plants are distinct at some level from the Eurasian as evidenced by the capacity to produce flared ocreae on aerial shoots when stranded. The Eurasian plants never do. Persicaria amphibia has over one hundred heterotypic synonyms just in North America! When recognized at the varietal level the correct name for the American plants is Persicaria amphibia (L.) Delarbre var. stipulacea (N. Coleman) H. Hara. At the subspecies level, the correct name is Persicaria amphibia subsp. laevimarginata (Hultén) Soják.

Persicaria coccinea, Scarlet Smartweed, is endemic to North America. It has almost as many synonyms. The correct name at the species level is Persicaria coccinea (Muhl. ex Willd.) Greene. As a variety of Persicaria amphibia the correct name is Persicaria amphibia var. emersa (Michx) J.C. Hickman.

Materials and Methods

Most taxonomic studies are conducted on a limited number of herbarium specimens, usually a handful and rarely numbering in the hundreds. Molecular studies today often use one sample per species. Herbarium specimens are very informative ways photographs and illustrations will never be. They can be dissected, measured and their DNA analyzed. But ecological data is often poor or absent. The conclusions presented here are based on close examination of the nearly 10,000 observations of Water Smartweeds (Persicaria amphibia sensu lato) in iNaturalist, most of the extant herbarium specimens and observation in the field.

An often overlooked and rarely discussed issue with many taxonomic studies is the logical problem of sample selection, potentially leading to confirmation bias and circular reasoning. These can be avoided by random sampling. But that has its own set of biases and could exclude plants with the traits we wish to analyze.

This study is essentially a meta-random sample. All of the available specimens and observations are analyzed with the same criteria. The thousands of observations made by others across the entire range of the taxa are included. The iNaturalist observations were made by almost 6,000 observers for a range of purposes unrelated to this study. They are examined and analyzed by me randomly as they appear in the simple taxon search and none are excluded.

Each specimen and observation is assigned a name based a suite of morphological criteria traditionally used to distinguish the taxa. These include leaf shape (when floating and stranded); ocreae flared or not; and length and shape of inflorescence spike.

Key to the species of Water Smartweeds. (For an extended key see Reveal and Atha, 2012).

A. Plants palustrine, usually with emergent leafy stems; ocreae never with flared apices; leaves ovate or lanceolate (widest below the middle); inflorescence spikes usually 2 (unequal), cylindrical, usually > 4 cm long; flowers usually scarlet...… Persicaria coccinea (Persicaria amphibia var. emersa).

A. Plants aquatic, usually with floating stems and leaves; ocreae with flared apices (when stranded); leaves oblong or elliptic (widest at the middle); inflorescence spikes usually 1, ovoid, < 4 cm long; flowers usually pink...…Persicaria amphibia var. stipulacea.


The hypothesis that there are two distinct species (Persicaria amphibia and Persicaria coccinea) and possibly one or more hybrids is strongly supported by the data.

When applied to the nearly 10,000 observations of Water Smartweed (Persicaria amphibia s.l.), the character states in the key above prove to be highly consistent and predictive. Each of the characters are significantly correlated, so that if you find a palustrine plant with ovate or lanceolate, aerial leaves it will have long, cylindrical inflorescence spikes (99.9+% of the time). On the other hand, if you find an aquatic plant with oblong, floating leaves it will have short, ovoid spikes (99.9+% of the time). The flared ocreae is significantly correlated with oblong leaves and short spikes. Richard Mitchell's studies found the same results, but he emphasized the significance the few apparent intermediates.

Geography is only sometimes considered a significant taxonomic character, probably because resolution of habitat and geographic ranges have traditionally been poor due to very limited samples available in herbaria and the fact that plants do in fact move around in seemingly unpredictable ways. iNaturalist is changing that in a big way. Now with thousands or sometimes tens of thousands of samples available we are getting closer to true and accurate range maps for many of the charismatic species (which includes these two). It is now apparent that correlation between geography and morphology is very strong and stark in these two species. More broadly, iNaturalist has now incorporated geography into its AI algorithms with significant improvement in predictive values. Richard Mitchell sampled only three populations from the vicinity of San Francisco.

Persicaria amphibia var stipulacea (plants with oblong leaves, short spikes and flared ocreae) is not found south of the Laurentide Ice Sheet (and see here) except in the mountain west and Mexico. See map of this species here. Note the observation near St. Louis, tracking precisely the southernmost extent of glaciation.

Persicaria coccinea (plants with ovate leaves, long spikes and no flared ocreae) is found nearly throughout North America except the extreme southeastern coastal plain and the far north. It has not been observed north of Edmonton, Canada, unlike Persicaria amphibia which extends through Alaska across the Bering Sea and into Asia. See map of this species in North America here.

The results suggest that Persicaria amphibia is somewhat rare in North America and that the species should probably be tracked by Natural Heritage programs throughout much of its range, especially along the southern boundary in New York, Pennsylvania, West Virginia, Kentucky, southern Ohio, Indiana, Illinois and Missouri. The true abundance at a local level is impossible to ascertain today because so many datasets do not distinguish the two taxa, even as varieties. But as the species are segregated in more data sets and floristic accounts it will become clearer how rare true Persicaria amphibia is today. Failure to recognize Persicaria amphibia as distinct from Persicaria coccinea could result in a cryptic decline in the former-- if it has not happened already. At the very least, the recognition of varieties is critical to conserve the gene-pools of both taxa. The most prudent course is to conserve all taxa wherever and whenever possible and that requires accurate identification of the taxa involved.

Results Summary

  1. Distinct morphologies. The vast majority of plants clearly exhibit a number of quantitative, discontinuous and correlated character states consistent with one species or the other.
  2. There are rare exceptions that appear to combine character states of the two species: See for example this observation. It has two, unequal elongate spikes like Persicaria coccinea, but has pale flowers, flared ocreae and oblong leaves like Persicaria amphibia. In this case, the plant overall is more like Persicaria amphibia, just with two, somewhat elongate spikes. It is one in 1,000 that seems to genuinely combine character states of both species. Before we jump to the conclusion that this plant and perhaps others like it "prove" they are one species, we have to eliminate all other possible explanations, like random mutation, hybridization, introgression, misinterpretation of the evidence or even one or more additional species.
  3. Distinct geographic ranges. This is becoming more and more clear as the observations accumulate. There are now almost 10,000 observations of the two species in North America and they clearly have different distributions. There are no plants with typical Persicaria coccinea character states in the far north. And there are no plants with typical Persicaria amphibia character states south of the Laurentide ice sheet in the eastern US. Very few plants better illustrate the correlation between past glaciation and present range than Persicaria amphibia.
  4. No single plant has ever been found to possess the traits of Persicaria coccinea at one end of the long rhizome and Persicaria amphibia at the other, even though there is ample opportunity for them to do so based on the position of the rhizome and level of inundation. For an example of this, see the observation here. I have seen most of the herbarium specimens of both species in North America and all the iNaturalist observations and I have never seen a plant with erect shoots and long inflorescences on the stem portion out of water and oblong floating leaves and short inflorescences on the stem portion in the water. But there are many examples of Persicaria amphibia with floating leaves at one end of the rhizome and erect shoots at the other.
  5. If they are one species with blended genetics, how can it be that no Persicaria coccinea like plant has ever been found with flared ocreae? That character is found exclusively in plants with the character states of Persicaria amphibia var. stipulacea.
  6. The most parsimonious explanation for plants with some intermediate character states is that the they are hybrids. To consider the entire range as one species based on these very rare specimens is the least good explanation. R.S. Mitchell did not consider this possibility (as the null hypothesis) when he lumped them for his PhD thesis in 1968.
  7. Taken all together these data are consistent with the consensus definition of a species in botany.


To consider the null hypothesis (for this study) and treat them as a single species (even with varieties or subspecies), as many did after 1968 (and some still do), requires ignoring the many morphological, genetic and geographic discontinuities between the taxa as proved by the evidence. These discontinuities are so distinct and so consistent, in most groups there would be no question they are two distinct species. The presence of a tiny fraction of individuals (ca. 0.01%) that appear to be intermediate in some characters does not prove they are a single species.

This looks like a classic case of convergence to me.

Lumping them together as a single species has very serious conservation implications. Conservation plans should conserve distinctive genetic lineages and conflating the two species could lead to the extinction of one or the other in the false belief that the "species" is preserved by the presence of at least some Persicaria amphibia s.l. We all know that most people tend not to use trinomials (myself included) and even heritage botanists and environmental surveyors will use the species name for convenience or uncertainty. U.S. Army Corps of Engineers data forms often omit subspecies or varieties, compromising the integrity and usefulness of EIS surveys that might include “Persicaria amphibia”


Thanks to iNaturalist, every observation used in this study is available to anyone with an internet connection. My materials and methods can easily be repeated exactly by anyone willing to spend the time. No fancy equipment, chemicals, algorithms, programs, institutional permission, journal subscription or specialized knowledge is required. That's what I love about natural history study and iNaturalist.


Atha, D. E. 2004. Polygonaceae. Pp. 308–310 in N. Smith, S. A. Mori, A. Henderson, D. Stevenson and S. Heald (eds), Flowering Plants of the Neotropics. Princeton University Press, Princeton.

Atha, D. E. & W. Carr. 2010. First Report of Persicaria hispida (Polygonaceae) from North America north of Mexico. J. Bot. Res. Inst. Texas 4: 561–564.

Atha, D. E., M. H. Nee & R. F. C. Naczi. 2010. Persicaria extremiorientalis (Polygonaceae) is established in the flora of the eastern United States of America. The Journal of the Torrey Botanical Society 137: 333–338.

Atha, D. and S. Rall. 2020. First report of Persicaria posumbu (Polygonaceae) for North America. Phytoneuron 2020-86: 1–7.

Burke, J. M. 2011. Revised subfamily classification for Polygonaceae, with tribal classification for Eriogonoideae. Brittonia. 63: 510–520.

Galasso, G., E. Banfi, F de Mattia, F. Grassi, S. Sgorbati & M. Labra. 2009. Molecular phylogeny of Polygonum L. s.l. (Polygonoideae, Polygonaceae), focusing on European taxa: preliminary results and systematic consideration based on rbcL platidial sequence data. Atti Soc. it. Sci. nat. Museo civ. Stor. Nat. Milano, 150(1): 113–148.

Kim, S. T. & M. J. Donoghue. 2008a. Incongruence between cpDNA and nrITS trees indicates extensive hybridization within Eupersicaria (Polygonaceae). American Journal of Botany. 95: 1122–1135.

Kim, S. T. & M. J. Donoghue. 2008b. Molecular phylogeny of Persicaria (Persicarieae, Polygonaceae). Systematic Botany. 33: 77–86.

Kim, S. T., S. E. Sultan & M. J. Donoghue. 2008b. Allopolyploid speciation in Persicaria (Polygonaceae): insights from a low-copy nuclear region. Proceedings of the National Academy of Sciences. 105: 12370–12375.

Massart, J. 1902. L'Accommodation individuelle chez Polygonum amphibium. Bull. Jard. Bot., Brux. [write out in full if that is the format required] 1(2): 73–95.

Mitchell, R. S. 1968. Variation in the Polygonum amphibium complex and its taxonomic significance. Univ. Calif. Pub. In Botany 45: 1–65.

Partridge, J. W. 2001. Persicaria amphibia (L.) Gray (Polygonum amphibium L), Biological Flora of the British Isles. Journal of Ecology 89: 487–501.

Reveal, J. L. & D. E. Atha. 2010. New combinations and typifications in Bistorta, Persicaria, Polygonum and Rumex (Polygonaceae). Brittonia 62: 243–263.

Reveal, J. L. & D. E. Atha. 2012. 8. Persicaria (L.) Mill. Smartweed, pp 236–250. in Cronquist et al. (eds), Intermountain Flora. The New York Botanical Garden Press, Bronx, NY.

Ronse Decraene L. P. & J. R. Akeroyd. 1988. Generic limits in Polygonum and related genera (Polygonaceae) on the basis of floral characters. Bot. Journ. Linn. Soc., London 98: 321–371.

Sanchez, A., T. M. Schuster, J. M. Burke & K. A. Kron. 2011. Taxonomy of Polygonoideae (Polygonaceae): a new tribal classification. Taxon. 60: 151–160.

Schuster, T. M., J. L. Reveal, K. A. Kron. 2011. Phylogeny of Polygoneae (Polygonaceae: Polygonoideae). Taxon. 60: 1653–1666.

Timson, J. 1965. A study of hybridization in Polygonum section Persicaria. Journal of the Linnean Society of London, Botany 59: 155–161.

Posted on Οκτώβριος 20, 2020 0708 ΜΜ by danielatha danielatha | 18σχόλια | Αφήστε ένα σχόλιο

Οκτώβριος 21, 2020

The Cosmopolitan Quickweeds (Galinsoga) of the World

Quickweeds. Shaggy soldier, Galinsoga quadriradiata (L), Gallant Soldier, Galinsoga parviflora (R), Photo 528808, (c) Kyle Jones, some rights reserved (CC BY-NC). Shaggy Soldier, Galinsoga quadriradiata. Two disc flowers and fruit with acuminate pappus scales (L); one ray flower and fruit with pappus scales nearly as long as corolla tube (R).Photo 9072390, Daniel Atha, public domain.

Galinsoga (Quickweed) is a genus of 15–30 species indigenous to the Americas and centered in Mexico (Canne, 1977; Canne-Hilliker, 2006). Two species are cosmopolitan, occurring in disturbed places in most countries of the world: Galinsoga quadriradiata and Galinsoga parviflora. Currently, only these two species are known from the continental US (USDA NCRS, 2020). Judith Canne-Hilliker who studied these plants for decades published works on the taxonomy of the genus and her work is the basis for modern floras that treat the species. A few additional studies have been done as well. For example, Braden and Cialone found that achenes of Galinsoga quadriradiata are significantly shorter and wider than those of Galinsoga parviflora (Braden & Cialone, 1971). Based on the literature and what could be observed in the field it was clear that the two species were distinct, but I was frustrated by the challenges in separating them, especially from fresh material in the field and from photographs on iNaturalist. The study described here was my attempt to address this problem. See the observation here for images of seedling development.

Materials and Methods
I examined all the herbarium specimens of Galinsoga quadriradiata and Galinsoga parviflora from North America at the New York Botanical Garden (NY) and the Brooklyn Botanic Garden (BKL) (over 300 specimens). Using a compound microscope and strong light, I sorted all specimens by the characters used by Judith Canne-Hilliker and flora writers to separate the two species. I ignored identifications and used only the traits of: rays with well-developed pappus about equaling the tube vs. rays with vestigial pappus scales or scales absent; pappus scales of the disk flowers awn-tipped vs. blunt.

Here is a good view of the pappus scales of the disk flowers and the pappus of the ray flowers in Galinsoga quadriradiata. In Galinsoga parviflora the ray pappus is absent.

I ended up with three piles, one much larger than the other two. The smallest pile consisted of specimens for which it was not possible to determine nature of disc and ray pappus scales. I then examined the two larger piles for hair and leaf teeth character states.

All of the specimens (100%) that sorted by lack of ray pappus and blunt disc scales (the middle sized pile) were found to have very short (<0.5 mm), unicellular hairs (on stems and leaves) and narrow-ovate leaves with mostly entire or merely crenate margins. The larger pile with ray pappus scales present and acute or awn-tipped disc pappus scales were all found to have long (> 0.5 mm) multicellular hairs (on stems and leaves) and wider leaves with definite acute teeth. It was then possible to sort the smaller, undetermined pile on the basis of hair and leaf characters alone so that all specimens were identifiable as one or the other species.

Outside of Mexico, Galinsoga quadriradiata is the most common of the two species. On the continent of Europe, the species occurs at just over twice the rate of Galinsoga parviflora (2,296 to 988, as of 17 Nov 2020). But in the United States, the species occurs at over ten times the rate of Galinsoga parviflora (2,214 to 214). In Asia it is 537 to 120. On the continent of Australia there are thirty-six observations of Galinsoga parviflora and no Galinsoga quadriradiata--so far.

Key to the Cosmopolitan Quickweeds of the World

1a. Stems and leaves pubescent with multicellular hairs 0.5–1(-2) mm long; leaf margins dentate, the teeth obtuse to acute; limb of ray flowers 2–5 mm long, the pappus scales about as long as the tube; pappus scales of disk flowers sharp-acuminate, lacerate..... Galinsoga quadriradiata

1b. Stems and leaves glabrous to sparse pubescent with unicellular hairs 0–0.5 mm long; leaf margins crenate, the teeth rounded; limb of ray flowers 0–2 mm long, the pappus scales minute or absent; pappus scales of disk flowers truncate to obtuse, fimbriate..... Galinsoga parviflora

The results obtained here and those of previous work elucidate several traits that are discrete, objective and unambiguous. Further, these traits are consistently correlated with each other to form a distinct assemblage of character states that unambiguously and consistently define the species. Each couplet (1a and 1b) in the dichotomous key above is a series of characters (separated by semicolons). The two species share these characters (such as pubescence or leaf margins) but not the values or attributes of that character. The values of each character are called character states. The character states exhibited by a species (such as hairs longer than 0.5 mm or shorter than 0.5 mm) are discrete and unambiguous for the two species. They are true for one species or the other, but not both. Each couplet is thus a summary of the assembled traits (characters and values) that define that species and can be used as a brief description (often called a diagnosis in older literature).

The process undertaken in the present study can instruct others seeking to distinguish taxa based on simple terms understood by a general audience and what can be observed with the naked eye or a hand lens. In photographs and often even in the field, it is not possible to dissect the specimen to examine minute and often highly technical features. But monographs, floras and even field guides may rely solely on minute and difficult characters to distinguish species (as in Galinsoga). For nearly all photographs of Galinsoga in iNaturalist, these characters are impossible to see and thus only tentative identifications were possible prior to this study. Working with preserved specimens I could examine under a microscope, I used the technical characters in a process of reciprocal illumination to find other, more easily observable traits by which the species could be identified. Based on the simple traits described here and summarized in the dichotomous key above, it is now possible for anyone to confidently identify Galinsoga in the field and from photographs such as those on iNaturalist.

This procedure may fail to reveal easily observable traits to distinguish cryptic species in other genera, but I have used it with success in Smartweeds (Persicaria) and in genera of other families.

Outside their native range, the two weedy species, Galinsoga quadriradiata and Galinsoga parviflora are often found growing side by side in mixed populations. Care should be taken when taking multiple photos in a single population.

It may only be a matter of time before additional Galinsoga species are found in the continental United States, especially in areas adjacent to Mexico, center of diversity of the genus.

Canne-Hilliker, J. 2006. Galinsoga Ruiz and Pavón, Pp. 180–182. in Flora of North America Editorial Committee (eds.). Flora of North America North of Mexico, Vol. 21. Magnoliophyta: Asteridae, part 8: Asteraceae, part 3. Oxford Univ. Press, New York; Canne, J.M. 1977. A revision of the genus Galinsoga (Compositae: Heliantheae). Rhodora 79: 319–389; USDA NCRS. 2020. Galinsoga. United States Department of Agriculture, Natural Resources Conservation Service accessed 21 October 2020; Braden, D.A. and J.C. Cialone. 1971. Characterization of two Galinsoga R. & P. species from New Jersey by achene length/width ratio and the presence of marginal cotyledonary hairs. Bulletin of the Torrey Botanical Club 98: 50–52.


This post is dedicated to Judith Canne-Hilliker, student and master of Galinsoga, who passed away in Guelph, Canada on October 27, 2013.

Except where explicitly stated, the words and research in this article are entirely my own. The facts belong to everyone. Please acknowledge that you heard it here first.

Posted on Οκτώβριος 21, 2020 0522 ΜΜ by danielatha danielatha | 14σχόλια | Αφήστε ένα σχόλιο

Οκτώβριος 26, 2020

American and Asian Jumpseed in North America

American Jumpseed, Persicaria virginiana

Persicaria virginiana (L.) Gaertn. American Jumpseed is a perennial herb to 1.5 m tall, from knotty rhizomes; stems are erect, slender and few-branched; ocreae strigose or tomentose, the apices ciliate; leaf blades ovate, 5–17 × 2–10 cm, reduced apically, the bases rounded, the apices acute to acuminate, strigose above and below, the margins setose; inflorescences to 45 cm long, very slender; flowers solitary or 2–3 per ocreolate fascicle; tepals 4, white, greenish white or rarely pink; achenes brown with hooked, persistent style. 2n=44.

The species is found across the eastern United States (and southern Canada), east of the 100th meridian, from southern Minnesota to Texas and Quebec to Florida, disjunct in central Mexico; found in rich deciduous forests, floodplain forests, dry woodlands, thickets; flowering July to October.

Synonyms include Polygonum virginianum, Tovara virginiana, Antenoron virginianum, Tovara virginiana f. rubra, Tovara virginiana var. glaberrima

The deflexed pedicels are under strong tension and when disturbed can propel the fruit 3–4 m from the plant (hence the name Jumpseed). The persistent hooked styles aid in animal dispersal. The plants are easy to recognize when young by the relatively large, ovate leaves and often very prominent maroon chevron that disappears as the leaves age. Small flies, bees and wasps are observed visiting the flowers and Robber Flies use the plants to hunt prey. Herbivory by Sawflies in the genus Allantus creates holes in the leaves (https://www.inaturalist.org/observations/52429526).

Asian Jumpseed, Persicaria filiformis (photo by Reuven Martin)

Persicaria filiformis (Thunb.) Nakai, Asian Jumpseed is sister to the American Jumpseed. They may share a common ancestor, but millenia of isolation, drifting continents and changing vegetation patterns caused the two species to diverge genetically, anatomically and chemically. But some taxonomists don't consider these differences enough to divide the species and treat them as two varieties of one species or just one species (under the oldest name, Persicaria virginiana). The one-species concept prevailed several decades ago and is often used in older literature and in the horticulture trade. Today there is ample data from multiple lines of evidence and strong support for separating the two as distinct species (Park et al., 1992; Mun & Park, 1995; Suh et al., 1997).

Morphologically, Persicaria filiformis and its cultivars can be distinguished by the elliptic leaves that are widest at or above the middle and with persistent purple markings, whereas Persicaria virginiana has ovate leaves, widest below the middle and purple markings only on young leaves. There are other subtle differences one can learn with practice. The American Jumpseed occasionally has pink flowers, so that alone is not enough to distinguish the species.

Cultivars of the Asian Persicaria filiformis ‘Painter’s Palette’, ‘Lance Corporal’, ‘Variegata’ and ‘Bat Wings’ are escaping from cultivation in the eastern United States and becoming naturalized. As early as 2017 and 2018, I noted many escapes in the Washington, DC area and began alerting people then to the nomenclatural issues, how to identify it and it's serious invasive potential. It has since spread more widely and become a serious pest in several areas of the northeast.

These introduced, artificial hybrids may interbreed with the indigenous Persicaria virginiana, eroding its genetic integrity and possibly compromising fitness and survival of this important indigenous American plant. The aggressive growth of the Asian Jumpseed also threatens other biodiversity by forming large, monocultural stands that crowd out other species.

Anecdotally, I have noticed that nearly every American Jumpseed has holes in the leaves, made by a native Sawfly. This Sawfly appears rarely to feed on the Asian Jumpseed. If the latter displaces the native species or corrupts it's genetic integrity, the viability of the Sawfly could be compromised along with its host plant. Let's just hope the technocrats in the invasive species industrial complex don't get the terrible idea to bring over an Asian Sawfly to "manage" this plant.

I recommend supporting the indigenous species and all its ecological benefits and removing the cultivar wherever found.

Except where explicitly stated, the words and research in this article are entirely my own. The facts belong to everyone. Please acknowledge that you heard it here first.

Suh, Y., S. Kim and C.W. Park. 1997. A phylogenetic study of Polygonum sect. Tovara (Polygonaceae) based on ITS sequences of nuclear ribosomal DNA. Journal of Plant Biology 40: 47–52.

Park, CW., M.G. Lee and H. Shin. 1992. A systematic study of Polygonum sect. Tovara (Polygonaceae): analysis of morphological variation. Korean Journal of Botany 35: 385–392.

Mun, J.H. and C.W. Park. 1995. Flavonoid chemistry of Polygonum sect. Tovara (Polygonaceae): a systematic survey. Plant Systematics and Evolution 196: 153–159.

Posted on Οκτώβριος 26, 2020 0440 ΜΜ by danielatha danielatha | 10σχόλια | Αφήστε ένα σχόλιο

Οκτώβριος 29, 2020

NYBG Science, Conservation and Humanities Webinars

Everyone is invited to these free Science, Conservation and Humanities Webinars from NYBG

Conserving the Rare Plants of New York (Friday, Nov. 6)

First Nations: Ethical Landscapes, Sacred Plants (Friday, Nov.13)

Here Today, Gone Tomorrow: Plant Extinction Now and Conservation Strategies for Tomorrow (Tuesdays, Nov. 17 & 24):

Sign-up to hear about upcoming NYBG Science, Conservation, and Humanities seminars.

Posted on Οκτώβριος 29, 2020 0915 ΜΜ by danielatha danielatha | 0σχόλια | Αφήστε ένα σχόλιο