Flora Capensis

Thiselton-Dyer, W. T.

doi:10.2307/4107506

Cited by 5 publications

(5 citation statements)

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“…The combination of peaks and their relative intensities can also be helpful in distinguishing between morphologically similar species. For instance, T. triflorum L.f. and T. scandens are closely related based on both morphology [6] and DNA data [7]. It is often difficult to distinguish them from one another-to such a degree that they might be considered conspecific based on morphological species concepts [27].…”

Section: Discussionmentioning

confidence: 99%

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A Study of Phenolic Compounds and Their Chemophenetic Value in the Genus Thesium (Santalaceae)

et al. 2022

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Despite the common use of Thesium species as food and medicine and the prevailing systematic (taxonomic) difficulties of the genus, the diversity of phenolic compounds and their chemophenetic value remain largely unknown. As part of ongoing systematic research on Thesium, phenolic compounds and their composition were investigated at four taxonomic ranks: generic, infrageneric, interspecific and infraspecific. Liquid chromatography–mass spectrometry, multivariate analyses, comparisons to DNA data and manual investigations of total ion chromatograms were conducted for 156 samples of 50 Thesium species, as well the two monotypic genera sister to Thesium (Lacomucinea and Osyridicarpos). A wide diversity of phenolic compounds, primarily flavonols, carboxylic acids, phenolic acids and associated derivatives, were observed. Rutin was the most common compound, followed by citric acid, isorhamnetin O-glucoside O-rhamnoside, kaempferol O-rutinoside, quinic acid and cryptochlorogenic acid. Chemophenetic data proved valuable at the generic and interspecific level and, to a lesser degree, at the infraspecific level. On the other hand, no distinct patterns were observed at the infrageneric level, nor did chemophenetic data correlate with infrageneric classifications based on genetic, geographical or morphological data. At the generic level, the patterns of phenolic compounds in Lacomucinea and Osyridicarpos overlapped with those of Thesium species, but no compound or group of compounds were unique to Thesium. At the interspecific level, total ion chromatograms of the species were largely distinct from one another and, with the exception of four species, remarkably consistent. Two related species (T. triflorum and T. scandens) with doubtful species boundaries had similar but distinct chromatograms, providing evidence of their retention as separate species. At the infraspecific level, the data were mostly inconclusive, but variation in samples of T. asterias revealed two morphologically distinct populations, one of which is possibly a species new to science. This study provides valuable preliminary insights into the phenolic diversity and chemophenetic relationships in Thesium, Lacomucinaea and Osyridicarpos and highlights the potential of chemophenetics in taxonomically problematic plant groups.

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Section: Discussionmentioning

confidence: 99%

“…Thesium plants are root hemiparasites that usually grow as herbs or subshrubs. They have linear or scale-like leaves that lack petioles and dry, nut-like fruits that often form elaiosomes [1,5,6]. Several species of Thesium have traditional and contemporary uses, particularly as medicines and functional foods in Africa and Asia [3].…”

Section: Introductionmentioning

confidence: 99%

A Study of Phenolic Compounds and Their Chemophenetic Value in the Genus Thesium (Santalaceae)

et al. 2022

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“…For example, the inflorescence structure of Thesium species is an important distinguishing character, but often varies considerably and is notoriously difficult to interpret. Its incorporation into traditional textual keys (Hill 1915(Hill , 1925 has resulted in several overlapping character states between divisions, the use of vague phrases such as "more or less" and other complex terminology. When taking into account that inflorescence type is only the second division in Hill's key, it is understandable that users have struggled to identify Thesium species correctly.…”

Section: Multi-access Keysmentioning

confidence: 99%

“…Furthermore, in challenging species groups, increased identification accuracy should arguably take preference over identification time. In the case of Thesium specifically, identification time using the interactive photographic key is unlikely to exceed identification time using the traditional textual keys provided by Hill (1915Hill ( , 1925.…”

Section: Character and Character State Delineationmentioning

confidence: 99%

“…Identifications are further complicated by the large number of species in the genus and the superficial similarities among species (Hill 1915). Current identification keys for South African Thesium species are textual keys (e.g., Hill 1925) that are often very difficult to use due to the overlap of character states between couplets (to account for intra-specific variability), as well as the difficulty in describing subtle differences in the general impression, size and shape (GISS) of species (García et al 2018). Thesium is therefore an ideal group in which to study cryptic characters and their representation in an electronic identification key.…”

Section: Introductionmentioning

confidence: 99%

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Electronic identification keys for species with cryptic morphological characters: a feasibility study using some Thesium species

Lombard¹,

Roux²,

Wyk³

2021

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The popularity of electronic identification keys for species identification has increased with the rapid technological advancements of the 21st century. Although electronic identification keys have several advantages over conventional textual identification keys and work well for charismatic species with large and clear morphological characters, they appear to be less feasible and less effective for species with cryptic morphology (i.e. small, obscure, variable characters and/or complicated structures associated with terminology that is difficult to interpret). This is largely due to the difficulty in presenting and illustrating cryptic morphological characters unambiguously. When taking into account that enigmatic species with cryptic morphology are often taxonomically problematic and therefore likely exacerbate the taxonomic impediment, it is clear that species groups with cryptic morphology (and all the disciplines dependent on their correct identification) could greatly benefit from a user-friendly identification tool, which clearly illustrates cryptic characters. To this end, the aim of this study was to investigate and develop best practices for the unambiguous presentation of cryptic morphological characters using a pilot interactive photographic identification key for the taxonomically difficult plant genus Thesium (Santalaceae), as well as to determine its feasibility. The project consisted of three stages: (1) software platform selection, (2) key construction and (3) key evaluation. The proposed identification key was produced with Xper3 software and can be accessed at http://www.xper3.fr/xper3GeneratedFiles/publish/identification/1330098581747548637/mkey.html. Methodologies relating to amongst others, character selection and delineation, visual and textual descriptions, key construction, character coding and key evaluation are discussed in detail. Seventeen best practices identified during this study are subsequently suggested for future electronic key compilation of species with cryptic morphology. This study indicates that electronic identification keys can be feasible and effective aids for the identification of species with cryptic morphological characters when the suggested best practices are followed.

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Thesium hispidifructum (Santalaceae), a New Hispidulous Species from Limpopo, South Africa and Notes on Enigmatic T. celatum

Lombard

Roux

2023

Taxonomy

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Two shrub-like Thesium species (subgenus Psilothesium) from the Limpopo and North West Provinces in South Africa are treated. Using morphological information from the literature, herbarium material (including types) and geographic information, specimens of the little-known T. celatum N.E.Br. and a new species, T. hispidifructum N.Lombard and M.M.leRoux sp. nov., are treated. A first comprehensive description of the Waterberg–Magaliesberg endemic, T. celatum, is provided along with diagnostic characters to distinguish it from its morphologically most similar-looking species, T. burchellii A.W.Hill. It has hitherto been classified as data deficient due to taxonomic reasons by the International Union for Nature Conservation (IUCN) but a status of Vulnerable is suggested. Thesium hispidifructum is recognised for the first time here and is endemic to Blouberg and Mount Letsjume. It is morphologically most similar to T. disparile N.E.Br. Its name was chosen with reference to its hispidulous to hispid indumentum covering the entire plant including the outside of the flowers and fruit. A threat status of vulnerable is proposed. Treatments of both species include detailed morphological descriptions, information on their distribution and habitat, comparisons and an identification key with morphologically similar species and photo plates.

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Flora Capensis

Cited by 5 publications

References 0 publications

A Study of Phenolic Compounds and Their Chemophenetic Value in the Genus Thesium (Santalaceae)

A Study of Phenolic Compounds and Their Chemophenetic Value in the Genus Thesium (Santalaceae)

Electronic identification keys for species with cryptic morphological characters: a feasibility study using some Thesium species

Thesium hispidifructum (Santalaceae), a New Hispidulous Species from Limpopo, South Africa and Notes on Enigmatic T. celatum

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