In 2025, Ranunculus ophioglossifolius Vill. was found in the Netherlands for the first time. The plants were growing in an old clay and sand quarry ('Tichelgaten'), now a nature reserve, near Buren in the Province of Gelderland. The species resembles R. flammula but is an annual with stalked and rounded lower stem leaves and with warty achenes. Ranunculus ophioglossifolius grows in open, species-rich reed vegetation, which is usually flooded in winter. It mainly occurs in countries around the Mediterranean and Black Sea; further north the species is rare and endangered. The species is not used as an ornamental and is not sold in garden centers. Therefore, the first occurrence of this species in the Netherlands is probably the result of a spontaneous settlement.
gelricum is an apomictic dandelion belonging to the section Palustria Dahlst. The species was described by van Soest in Acta Botanica Neerlandica in 1965. Until the year of publication, Taraxacum gelricum has been collected under the name T. limnanthes Hagl. subspecies limnanthoides Soest, a form which currently is considered to correspond with T. palustre (Lyons) Symons. Taraxacum gelricum and T. palustre are not always easy to distinguish; this is especially true for herbarium material that was collected a long time ago. In the field, however, the two species clearly differ from each other: well-developed plants of T. gelricum can easily be recognized by their leaves, which have straight, very pointed lobes, and they can be further distinguished from T. palustre by the loose (not appressed) outer involucre bracts, which are narrower than those of T. palustre and have scarious borders that also are much narrower. Taraxacum gelricum is a very rare species with a limited distribution area. In the Netherlands, it has been found with certainty in the Gelderse Vallei, in France in a few places in coastal areas along the English Channel and the Atlantic Ocean, while in Germany an old 19th century record is known from the area around M & uuml;nster. There are no recent records of the species from France and it is considered to be extinct in Germany. In the Gelderse Vallei, Taraxacum gelricum was found in the 1960s in three locations, where it was growing in meadows as part of the fen meadow association Cirsio-Molinietum. As far as known, the species has disappeared from these meadows due to the enormous decline in surface and quality of this biotope. In the period 1977-1993 the species was found in two locations in the northern part of the Gelderse Vallei that were situated on the landside along the old dyke of the former Zuiderzee, of which the location near Nekkeveld was the richest. There the species grew in abundance, together with Triglochin maritima and Taraxacum palustre, in a subhalophilous wet meadow. Although Taraxacum gelricum is nowadays still present at Nekkeveld, it occurs there only in small numbers. Halophytes do not occur there anymore. The current vegetation can be assigned to the Ranunculo-Senecionetum aquatici, a Calthion palustris association. In this rather closed grassland, T. gelricum is limited to some bare spots caused by mowing. This also applies to T. akteum and T. anglicum, critical species that used to occur in many locations along the eastern coast of the Zuiderzee. The hay-meadow derives its botanical value mainly from the special dandelions flora. The presence of T. frugale, T. lucidum, and T. aequilobum also contribute to the botanical value of the site.
A description and two woodcuts of an orchid in the herbal of Matthias de Lobel (1581) appear to represent Gymnadenia densiflora, whose status as an independent species has recently been confirmed by genetic analysis. The pictured specimens came from the dunes near The Hague, the Netherlands. Data on the past and present occurrence of G. densiflora in the Dutch dunes are briefly summarized. There are occasional mentions of abundant presence in some locations, but nowadays it has become very rare in these dunes.
the summer of 2023, and again in 2024, a large population of an unidentified Centaurium was discovered at a recently excavated site along the River Meuse near Grevenbicht (Koeweide /Trierveld), the Netherlands. In 2024, morphologically identical plants were also found on the Belgian side of the river in Stokkem (Kerkeweerd), and in 2025 between Maasband and Meers, again on Dutch territory. The plants were morphologically highly uniform, fully fertile, and bore a striking resemblance to C. tenuiflorum, a species predominantly native to the Mediterranean region. However, several morphological traits also appeared intermediate between those of the native species C. erythraea and C. pulchellum. To determine the plants' identity, genetic analyses were conducted and their genome size was measured using flow cytometry. The results demonstrated that, despite their apparent resemblance and fertility, the plants do not belong to C. tenuiflorum, but to the hybrid between C. erythraea and C. pulchellum. This taxon has previously only been recorded in the British Isles, France, and Germany, and thus the recent finds represents a new record for both the Netherlands and Belgium.
Hieracium gulianum is described as a new species from the Netherlands. The description is accompanied by illustrations. The species is only known from a very restricted area near Geulhem and Valkenburg in South Limburg, where it occurs in open vegetation on steep limestone cliffs in the valley of the River Geul. The total number of individuals is estimated as being less than 200. Hence, the species is considered critically endangered according to the IUCN criteria. Hieracium gulianum faces two main threats: succession of the open vegetation in which the two populations occur and vegetation clearance of the rock faces in Geulhem.. We strongly plea for a special action plan to ensure the biodiversity value of the limestone cliffs in South Limburg, which provide a habitat that is very rare in the Netherlands.
This paper elucidates the indispensability of herbarium collections regarding the discovery of cryptic species and the knowledge of their plasticity, ecology and geography. In Table 1 fifteen species are listed that had been 'hidden' due to their resemblance to related species, and have been identified as members of the flora of the Netherlands after 1900. From these Oxybasis chenopodioides is chosen as an example, because it has remained 'cryptic' inasmuch as it is still insufficiently recognized. Macroscopic features that were considered characteristic of Oxybasis chenopodioides are reflected in several epithets on species or variety level: fleshiness (crassifolium), with almost smooth-edged leaves (paucidentatum), having an inflorescence resembling Dysphania botrys (botryoides). However, such features may also occur in other Oxybasis species. The distinguishing character state was not mentioned until 1841, when Karelin & Kirilov described the strong and peculiar dimorphy of hermaphroditic and female flowers in the same cluster. Because of the smallness of female flowers (reflected by the epithet minutiflora chosen by these authors) the plant should be viewed through a stereo microscope. In 1955 -1964 subsequent revisions by S. J. van Ooststroom and P. Aellen revealed a number of finds in the western half of the Netherlands, the majority of which date back to the 19th century (Table 2). Most of these finds were identified before as Chenopodium urbicum or as Blitum rubrum / Chenopodium rubrum. After van Ooststroom's and Aellen's revisions only few new specimens of Oxybasis chenopodioides have been collected in the Netherlands, all of them were gathered in the estuary in the southwest, i.e. in the Province of Zeeland and the former island of Goeree in the Province of Zuid-Holland (Fig. 10). A number of specimens of Oxybasis chenopodioides come from brackish habitats. Among others it was collected along the former Zuiderzee before this inland sea was closed in 1932 and became a freshwater lake. Some other finds relate to creeks and an old breakthrough vortex that remained saltish after being embanked. The richest actual site of O. chenopodioides has originated from reclamation of saliferous peat for salt-making. However, this species also occurred in non-saline habitats, viz. near villages in dune areas and in urban environment, notably at the edge of Amsterdam. In the middle of the 19th century its was twice collected in arable land. Therefore, its apparent dis appearance from the northwestern part of the Netherlands still needs to be explained. Finally, it should be noted that Blitum chenopodioides, described by Linnaeus (1771), was considered a monstrous form of Blitum virgatum by A. J. Retzius according to Willdenow (1797). This remark has been overlooked by Aellen (1933) when choosing Blitum chenopodioides as a basionym for the present species.
After the drastic redevelopment of the banks of the River Meuse in recent years, on both the Dutch and Belgian sides of the river, numerous exceptional exotic plants unexpectedly appeared. Although their precise introduction vector is difficult to determine with certainty, most of these species have most likely germinated from the old, long-buried seed bank that was uncovered by the works. The seeds were introduced many decades ago (at least 50 but perhaps more like 100 years ago, or even longer) via the wool processing industry, about 50 km further upstream, along the River Vesdre in Belgium. Here, we present a commented and illustrated overview of the 59 taxa observed in recent years. They belong to a very limited number of families that are known to have hard, long-lived seeds (mainly Fabaceae and Malvaceae, which together represent 48 taxa). Most taxa are native to the Mediterranean area, but are often widely naturalized elsewhere in the world, including in wool farming areas, while some are endemic to Australia, South Africa, or South America. The following species had not been recorded before in the Netherlands: Cullen cinereum, Dichondra micrantha, Erodium carolinianum, Lotus ornithopodioides, Malva olbia, Malvastrum americanum, Sida acuta, S. rohlenae, S. sivarajanii, Sphaeralcea purpurata, Tarasa tenella, Trifolium hirtum, T. spumosum, and T. squarrosum. Nicotiana glauca was reported for the first time in Belgium. The most remarkable species are depicted. Perhaps these records are of limited relevance for the Dutch and Belgian flora, because - as in the past - probably none of these wool aliens will be able to establish permanently (although this cannot be ruled out entirely, given the changing climate). Our findings highlight the exceptional longevity of seeds of certain plant families.
In the summer of 2024, a small population with a few dozen plants of Damasonium polyspermum, a vulnerable Mediterranean species, was found on a gravel bank of the River Meuse. Its nearest extant populations are located in the south of France, at a distance of almost 1,000 km. Although the introduction vector can only be speculated about, an introduction by migrating waterfowl seems most likely. For the Dutch flora, this discovery may turn out to be merely anecdotal, as the species probably will not be able to survive in this locality. However, the discovery of a new species for a country inevitably involves determining its residence status (native versus non-native). The status assigned may have major consequences for certain ecological and/or policy perspectives (respectively the possible protection versus eradication of the species concerned). Although the importance of this status cannot be under estimated, it must be accepted that it is rarely unambiguous and often a mere educated guess. A number of aspects are considered and relevant literature is assessed. Although the species probably arrived at the Meuse in a natural way (through ornithochory, without any human intervention) but probably will disappear again in the short term, it should be classified as an ephemeral species, without the question of indigeneity arising. This could of course change if the species were to become permanently established, e.g. as a result of a warming climate.
hybrids can be added to the Dutch Carex flora, Carex x prahliana [C. lasiocarpa x C. rostrata] and C. xrotae [C. appropinquata x C. paniculata]. The total number of Carex species in the Netherlands is currently 74 and 35 Carex hybrids are known.
During the treatment of Ornithogalum L. for Nova Flora Neerlandica, doubts arose about the identity of the Dutch plants hitherto reported as O. nutans L. In this article, we address this problem and present a table with characteristics to distinguish O. nutans from O. boucheanum (Kunth) Asch., as well as their hybrid, O. xvigeneri Ciferri & Giacomini.
- In 1838, the young Dutch botanist L. H. Buse and his brother H. D. Gildemeester Buse found a colony of Splachnum ampullaceum (Cruet Collar-moss) with sporophytes on the moorland between Beekbergen and Loenen on the Veluwe (Province of Gelderland), south of the Beekbergerwoud. This was the first documented find of S. ampullaceum in the Netherlands. In 1840 they found this species again in the same area, now in the company of J. Wttewaall. The colony they found was richly provided with sporophytes. They collected a lot of material of this colony. Buse later included this collection as number 15 in his exsiccata series Musci Neerlandici. After 1840, S. ampul laceum was found a few more times in the Netherlands in the 19th century, but it remained rare. It even seemed that the species has become extinct in the Netherlands since 1910. However, the species was found again in 2010 in the Witterveld near Assen (Province of Drenthe). This was a colony of plants without sporophytes growing on cow dung. Splachnum ampullaceum belongs to the Splachnaceae and grows in Western Europe almost exclusively on dung of herbivores in moist habitats such as cow dung in wet moorlands and peat bogs. Spores of this moss are dispersed by flies. This article discusses the possible causes of the decline of S. ampullaceum in the Netherlands and neighbouring countries and also provides information about the first 19th century collectors of this moss species.
Digitalized botanical collection data often lacks location data in the form of geographical coordinates, limiting a wider use of the data. Specimens of Dutch plants, mosses and fungi in the Naturalis botanical collection (herbarium codes AMD, L, U, and WAG) were initially digitized with only 3 % of the records having geographical coordinates. In a two year project, coordinates were added to the specimen records by means of (semi)automated techniques and crowdsourcing. Coordinates were inferred from location data present on the specimen labels such as toponyms (including those with typographical errors and abbreviations), grid square codes and other local coordinate systems. Finally, 75 % of about half a million specimens of vascular plants could be georeferenced with a precision of 5 km or better.
- The goal of this study is to describe the morphological features of the indigenous variant(s) of Acer campestre (Field Maple) occurring in the Netherlands. Hitherto little study has been done on this subject although A. campestre is one of the native woody plants that is widely planted (Duistermaat 2020). Indigenous populations in particular are expected to be more resilient to climate change due to thousands of years of adaptation to climate changes since the last glaciation period and because they are probably having a high genetic variability. For this study, material from different ancient coppice stools, pollarded trees, and hedges from the natural distribution area of the species in the Netherlands was examined to assess the morphological variation and morphological similarities between populations. This article wishes to contribute knowledge regarding the indigenousness of native trees and shrubs for the purpose of vegetation science and conservation of indigenous woody plants.
- Very little research has been done on the stoneworts (Characeae) of the Caribbean islands. This also applies to the stoneworts of the Dutch Caribbean islands Bonaire and Curacao (Leeward Antilles). Hitherto, only stoneworts which happened to be collected between 1930 and 1959 during studies of other groups of organisms formed the basis of our knowledge. Eight taxa are known from Bonaire and Curacao. Early 2023, the first author made a targeted survey for stoneworts on Bonaire and Curacao. His survey had the great advantage that the rainy season prior to the survey was extremely wet, which resulted in much more fresh water on the surface of the islands than during the wet seasons in previous years. Nevertheless, only three taxa were found: Chara armata, C. leptosperma, and C. zeylanica f. elegans. The latter taxon appeared to be quite common on both islands, sometimes filling entire water bodies, while Chara armata was only found in a single location on Curacao. Chara leptosperma is new for Bonaire and Curacao. The cause of the possible decline in the number of stonewort species is not quite clear.
The series Suberecti of the genus Rubus consists of three classic species, which are surrounded by similar but not identical forms. Some of these deserve a separate status. Rubus transitorius (close to R. ammobius) and R. cubirianus (close to R. scissus) were already described. To these two a new species, R. lucidicaulis (close to R. nes-sensis) is added. In addition, a form of R. scissus with deep red prickles from the British Islands has been described here as f. rubrisetus to clarify that this form is not a representative of the R. scissoides complex but is closely related to R. scissus. For the old name R. polonicus, belonging to the R. nessensis group, an epitype is designated. However, its precise taxonomic position must be clarified before drawing any further nomenclatorial conclusions.
- In 1926, Zahn described Hieracium murorum subsp. henrardii in van Soest's (1926) revision of the genus in the Netherlands on the basis of one single collection made by J. Th. Henrard near Ampsen (Province of Gelderland) in the autumn of 1908. Since the plants seem to be very a-typically developed, like often in late flowering specimens of Hieracium sect. Hieracium, it appeared very unlikely that the identity of the plants would ever be revealed. Several attempts to search for plants of this section in the direct vicinity of Ampsen were unsuccessful and it was believed that Henrard's hawkweed had disappeared. However, between 2007 and 2012 we collected several plants in a somewhat wider region around Ampsen (i.e. Castle Hackfort in 2007 and the estate Kieftskamp near Linde in 2012) which, after a thorough study of the material, have been identified with certainty to belong to the same taxon. Two specimens in Van Soest's herbarium in L that were collected near Castle De Wildenborg and the estate Kieftskamp in 1937 proved to belong to this taxon as well. All plants have the typical long petioles found in Hieracium murorum subsp. henrardii and have similar (rather peculiar) teeth at the leaf margins. After an additional and thorough search in L, we located two more herbarium specimens that belong to this taxon. They were collected by D. Douwes near Huize Zelle (Province of Gelderland) in 1981 and Linde in 1982. It should be noted that P. Heukels identified Douwes' plant from Huize Zelle already in 1981 as H. murorum subsp. henrardii. Several unidentified specimens of Hieracium sect. Hieracium were send on loan to Torbjorn Tyler (Lund, Sweden), amongst which one plant collected in the park of Palace Het Loo near Apeldoorn. Tyler identified this plant as Hieracium monstrosum, a species described by Hylander based on material from the park of the Malsaker estate near Ytterselo in 1943 and only known from the type locality and the park of Castle Tynnelso near overselo, both in the Province of Sodermanland, Sweden. After examination, we can only conclude that the specimen from Het Loo belongs to the same taxon as those from Ampsen, the Kieftskamp, De Wildenborgh, Huize Zelle, and Linde. Consequently, H. monstrosum and H. murorum subsp. henrardii are conspecific. Just like in Sweden, H. monstrosum in Gelderland is found in castle and estate parks and it probably was introduced between 1750 and 1935 as a contamination of grass seeds ('wood lawn neophyte'). An extensive description and photos of H. monstrosum are given to facilitate its future recognition.
Cardamine corymbosa has its natural range New Zealand. In the last quarter of the last century, however, this species has been accidentally introduced into Western Europe via the transport of potted plants. The introduction started in Scotland in 1975 and a few years later the species was found all over Great Britain. In Belgium and the Nether lands the species appeared as a weed in ornamental horticulture around 2000; it was reported for the first time from a garden in the Province of Friesland. In Germany the species appeared for the first time in a nursery in Oldenburg, Lower Saxony, in 2005. While the first European sites were gardens, parks, and in particular cemeteries, in the Netherlands the species colonised urban areas as well and it is now established in almost all major cities. In the most recent 2020 Checklist of the flora of the Netherlands, C. corymbosa has even already been given the status Modified Letter Turned Commanaturalized'. The small size of the plants, the few-flowered inflorescences, and the pollination mechanism of Cardamine corymbosa are remarkable features. In 2021 and 2022, the authors monitored a new population of this species in the old inner city of Deventer. This population consists of around 80 scattered rosettes which are growing between the bricks on the side of a street. After the first bloom in March, with open flowers with relatively large white petals, later bloom with inconspicuous cleistogamous flowers follow throughout the year. The long slender green siliques are striking and present until very late in the year. While the literature reports the colour of the plants as being green with a gradient to purple-brown, the Deventer plants are entirely bright green. The species' strength to survive is also remarkable. Despite frequent and intensive weed control of the Deventer site by using steam or mechanically brushing, the plants survive and hardly seem to suffer. The species can be considered as one of the permanent residents in at least the urban areas of the Netherlands.
- Hypericum anagalloides, a species from North America, was discovered in a water storage facility in Groot Hoenlo (municipality of Olst, Province of Overijssel). This is the first time the species is found in the Netherlands. Up to now its origin is unclear. We describe the locality and the vegetation where the species was found. As it shows signs of invasive behaviour we suggest to be alert for new localities and to extend the identification key in Heukels' Flora to enable fast recognition and action.
- The first author found Carex bohemica at a private estate in the Province of Noord-Brabant on 19 August 2022, a species which had never been found before in the Netherlands. The site concerns a natural place of this species, which was previously found in Belgium in 2010.
- In this paper, we describe Hieracium doryphorum Haveman & De Ronde, a new species of Hieracium sect. Vulgata (Griseb.) Willk. & Lange. Specimens of this new species were previously misidentified as H. festinum Jord. (sub nomine H. vulgatum Fr. subsp. festinum (Jord.) Zahn), but the new species differs from the latter by its elongated and strongly dentated leaves, the absence of stellate hairs on the involucrum, and the long and slender glandular hairs in the inflorescence. Hieracium doryphorum is locally common in the northern Veluwe, Province of Gelderland, and at the Hondsrug, Province of Drenthe, the Netherlands, and it was also sparsely found elsewhere in the Netherlands in the Provinces of Overijssel, Drenthe, and Groningen.
