Dense Indumentum Research Articles

A new Senecio (Asteraceae) from the Anjaneri Hills of Nashik, India

A new species of Senecio (Asteraceae, Senecioneae), Senecio anjanericus is described and illustrated from the Anjaneri Hills of Nashik district, Maharashtra, India, based on morphological and cytogenetical studies. The species resembles Senecio bombayensis, but differs from it in small size of the ligules, presence of conspicuous foliose supplementary bracts and dense indumentum on stem. The somatic chromosome number was observed to be 2n = 2x = 20, with all the chromosomes exhibiting median region centromeres. A detailed morphological description, illustration and karyotypic features of the new species are provided.

Campanula quercetorum subsp. densiflora: A New Taxon of Campanula (Campanulaceae) from Eastern Anatolia (Türkiye)

Türkiye is a crucial country for the genus Campanula diversity in the Mediterranean Basin. Also, more than half of Campanula species in Türkiye are endemic. In this paper, Campanula quercetorum subsp. densiflora (Campanulaceae) is described as a new subspecies from Tunceli (Türkiye). According to its morphological features, it belongs to the Campanula subgen. Campanula sect. Rupestres. This section mainly consists of perennial polycarpic or perennial monocarpic and chasmophyte species. It is morphologically closely related to C. quercetorum subsp. quercetorum. It is easily distinguished from C. quercetorum subsp. quercetorum by its dense inflorescence, dense indumentum, densely hairy corolla surface, conspicuous purplish-blue corolla veins, and ascending to erect habitus. Diagnostic characteristics, a full description, and comprehensive photographs are given in this study.

Reinstatement of the name Petalidium ovatum (Acanthaceae), with an amplified description of the species

The name Petalidium ovatum is reinstated and an amplified description is provided for a species of Petalidium confined to Namibia. Petalidium ovatum used to be treated as a synonym of the widespread P. englerianum, but morphological characters support the reinstatement. Petalidium ovatum is a range-restricted species, only known from the Khorixas-Bergsig area in the Kaokoveld Centre of Endemism, northwestern Namibia, where it grows on arid hillsides and along ephemeral riverbeds and drainage lines. Diagnostic characters for P. ovatum include the pale grey, often almost white, appearance of the plants, vegetative parts with a dense white indumentum of both stellate and dendritic trichomes, flowers borne in short few-flowered dichasia, bracts oblanceolate with apices acute or obtuse, and bracteoles widely ovate. The flowers of P. ovatum are distinctive in having the anterior corolla lobe partly or completely yellow, the others burgundy, and with the two upper lobes connate towards the base for almost half their length. A comparison of some of the more prominent morphological features to differentiate Petalidium ovatum from P. englerianum, its morphologically most similar relative, is provided. Based on IUCN Red List categories and criteria, a conservation assessment of Least Concern (LC) is recommended for the reinstated species.

Lindernia adami-hefiedi (Linderniaceae)—a new species from Madagascar

The new species Lindernia adami-hefiedi from Madagascar, Montagne d’Ambre is described and illustrated. It differs from Lindernia rotundifolia, and related species in the dense indumentum with long-stalked glandular hairs, the matt leaves, the long pedicel, the large corolla and the long free staminodes. Additional material of the closely related species L. lemuriana, L. oblongifolia, L. rotundifolia and L. viguieri is studied and a key to the species of Lindernia s.str. in Madagascar is provided. Herbarium studies revealed that Ilysanthes oblongifolia is the oldest name for Lindernia paludosa, and the relevant new combination is made here.

Molecular phylogenetic and morphological support for the recognition of Friesodielsia lalisae (Annonaceae), a new species from S Thailand

Thirteen species of Friesodielsia Steenis (Annonaceae) and 11 representatives of related genera were included in molecular phylogenetic analyses using up to six plastid DNA regions (psbA-trnH, trnL-trnF intergenic spacers; trnL intron; matK, ndhF, rbcL exons). The results support the recognition of a new species, F. lalisae Damth., Baka & Chaowasku from Narathiwat, S Thailand, as belonging to one of the two major clades of Friesodielsia. The members of this clade show outer petals that separate at anthesis and have a concave basal portion, while members in the other major clade exhibit outer petals that separate early during developmental stages and have a flat base. Friesodielsia lalisae is described and illustrated. It is most morphologically similar to F. argentea (J. Sinclair) Steenis and F. glauca (Hook. f. & Thomson) Steenis but differs from the two by having dissimilar sepal shape, higher proportion of inner petal to outer petal length and longer inner petals. The new species additionally differs from the former by having different leaf base and from the latter by having denser indumentum on young twigs and shorter flowering pedicels. Narathiwat, a province to which the new species is endemic, seems to be one of the most underexplored areas in Thailand as evidenced by a number of species described based on recent material. The conservation status of the new species is provisionally assessed as Critically Endangered. Citation: Damthongdee A., Khunarak N., Kaeokula S., Saengpho C., Wiya C., Ue-aree P., Baka A., Aongyong K. & Chaowasku T. 2023: Molecular phylogenetic and morphological support for the recognition of Friesodielsia lalisae (Annonaceae) a new species from S Thailand. – Willdenowia 53: 45–55. Version of record first published online on 10 April 2023 ahead of inclusion in April 2023 issue.

Histochemical Analysis and Ultrastructure of Trichomes and Laticifers of Croton gratissimus Burch. var. gratissimus (Euphorbiaceae).

Croton gratissimus (Lavender croton) possesses three distinct secretory structures. These include lepidote and glandular trichomes and non-articulated unbranched laticifers. The lepidote trichomes form a dense indumentum on the abaxial surface of the leaves and canopy the glandular trichomes. Although assumed to be non-glandular, transmission electron microscopy (TEM) indicated high metabolic activity within the stalk and radial cells. Glandular trichomes are embedded in the epidermal layer and consist of a single cell which forms a prominent stalk and dilated head. Laticifers occur on the mid-vein of leaves and are predominantly associated with vascular tissue. In the stems, laticifers are associated with the phloem and pith. Both trichome types and laticifers stained positive for alkaloids, phenolic compounds, and lipids. Positive staining for these compounds in lepidote trichomes suggests their involvement in the production and accumulation of secondary metabolites. These metabolites could provide chemical defense for the plant and potentially be useful for traditional medicine.

Two new leptosporangiate ferns from in situ volcanic ash of the Whetstone Horizon (Kladno Formation, Pennsylvanian), Pilsen Basin, Czech Republic.

A new leptosporangiate fern genus, Discosoropteris, is recognized and two species circumscribed from the Duckmantian-age Kamenný Újezd locality of the Pilsen Basin, Central Bohemia based upon tripinnate fronds preserved in the Bělka tuff. The sphenopterid pinnules bear massive disc-shaped sori, either on the laterals or midvein, that contain up to 80 annulate sporangia. The trilete microspores vary from laevigate, to microgranulate, microspinate, or finely reticulate and, thus, are comparable to both Leiotriletes and Granulatisporites. This variance is deemed most likely to reflect different stages of spore maturation. The cuticle preserves anomocytic stomata on the pinnae and a dense indumentum of multicellular uniseriate trichomes on the rachis. Trichomes are also dense within the sori where they appear to approximate the utilities of an indusium, whether for limiting environmental exposure or access to herbivores. These compression fossils preserve some traces of internal anatomy, including scalariform tracheids and bundle sheath cells that show signs of puncture-feeding herbivory. The bearing stem is unknown but preservation of the fronds within the tuff suggests they were elevated on a short, upright, self-supporting axis. Comparisons are drawn with other Carboniferous taxa, particularly Discopteris; review of the complex history of these alternatives suggests Discosoropteris is best left as incertae sedis within the basal leptosporangiate ferns rather than adding to the confusion by attempting a family-level assignment at this time.

Stinging Trichomes in Apocynaceae and Their Evolution in Angiosperms.

Stinging trichomes are rare in plants, occurring only in angiosperms, where they are reported for a few genera belonging to six families. Although there is no report of stinging trichomes in Apocynaceae, previous fieldwork collections of Fischeria and Matelea caused us a mild allergic reaction on the skin when we contacted the dense indumentum of the plants. This fact associated with the well-known presence of glandular trichomes with acute apex in both genera raised suspicions that stinging trichomes could be present in the family. Hence, this study aimed to investigate the likely occurrence of stinging trichomes in Fischeria and Matelea. We analyzed vegetative shoots and leaves of Fischeria stellata and Matelea denticulata through the usual procedures of light and scanning electron microscopy. We also performed several histochemical tests to investigate the chemical composition of trichome secretion. We detected that glandular trichomes occur throughout the surface of the leaf and stem. They are multicellular, uniseriate with an apical secretory cell, which has a dilated base and a needle-shaped apex. The secretion is compressed into the acuminate portion of the apical cell by a large vacuole, and crystals are deposited in the cell wall in a subapical position, providing a preferential site of rupture. The secretion, composed of amino acids and/or proteins, is released under mechanical action, causing skin irritation. Based on our detailed morphological and anatomical analyses, and in the functional aspects observed, we concluded that the glandular trichomes in Fischeria and Matelea can indeed be classified as stinging. Thus, Apocynaceae is the seventh family for which this type of trichome has been reported. We also compiled information on stinging trichomes in all families of angiosperms. Their phylogenetic distribution indicates that they have evolved at least 12 times during angiosperm evolution and may represent an evolutionary convergence of plant defense against herbivory.

<p><strong><em>Aeschynanthus rejieae</em> (Gesneriaceae), a new species of lipstick vine from Tawi-Tawi, Philippines</strong></p>

Aeschynanthus rejieae from Panglima Sugala, one of the few remaining forested areas in Tawi-Tawi, Philippines, is illustrated and described as a new species. It resembles A. obconicus and A. ovatus by the ovate leaves and dense indumentum in the external calyx and corolla. However, A. rejieae is distinguished by having leaves that have persistent sparse pubescence, campanulate calyx with dense hirsute indumentum both internally and externally, and ovary with a glandular cilia. This species is named after Rejie Sahali-Generale, who initiated the biodiversity conservation in Panglima Sugala. This new discovery further highlights the urgent need to study and conserve the remaining forests of Tawi-Tawi.

Foliar micromorphology, ultrastructure, and histochemical analysis of Barleria albostellata C.B. Clarke

Barleria albostellata (Acanthaceae), is a valuable medicinal plant with a broad spectrum of antibacterial and anti-inflammatory activities. This study aimed to characterize the micromorphology, distribution, and chemical composition of the trichomes present on the leaves and stems of B. albostellata using light and electron microscopy and histochemistry. Morphological observations using stereo and scanning electron microscopy (SEM) revealed a dense indumentum bearing numerous non-glandular trichomes on the leaves and stems of B. albostellata. The histochemical and SEM analyses revealed the presence of five morphologically distinct glandular capitate trichome types, multangulate-dendritic branched (MDB) non-glandular trichomes and a glandular head attached to a branched non-glandular trichome. Transmission electron micrographs showed that numerous plastids, mitochondria, and endoplasmic reticulum cisternae were actively involved in the secretory process. The stained leaf and stem sections indicated the presence of alkaloids and phenolics as the major medicinal compounds in glandular and non-glandular trichomes. To our knowledge, this study represents the first detailed report describing the key micromorphological features of the foliar structures of B. albostellata as well as the preliminary chemical composition of the secretions produced by these structures.

Sonerila calcicola (Melastomataceae), a new karst dwelling species from Northern Thailand

Sonerila calcicola J.Wai & J.M.Hu, a new species discovered from the limestone karst area of Tak province, Northern Thailand is here described and illustrated. Photographs, illustration, distribution map and comparison with the morphologically similar species, S. parishii Stapf, are also provided. Sonerila calcicola differs from S. parishii in having stout, succulent stems with a denser indumentum, creamy or yellowish white anthers, smaller hypanthium and ovary. This new species is confined to limestone substrate.

Trichome micromorphology in Alcea L. and allied genera (Malvaceae) and its systematic implication

Trichomes of 26 species of Alcea (Malvaceae) were investigated using light (LM) and scanning electron microscopy (SEM). The trichomes show a great micromorphological variation, which provides data useful for species delimitation in Alcea. Two basic types of trichomes could be distinguished in Alcea and allied genera: glandular and eglandular. The glandular trichomes could in turn be subdivided into two subtypes: capitate and clavate. The eglandular trichomes could be subdivided into five subtypes: simple, fascicled, stellate, fascicled‐stellate and pluri‐radiate. Characters of taxonomic interest are: trichome density (glabrous to dense), number of arms per trichome, orientation relative to the epidermal surface (appressed to erect) and presence/absence of a stalk. According to the results the species of Alcea can be divided into four informal groups based on trichome types. The results further support the exclusion of the annual Althaea species from the perennial ones and their close relationship to Malva. In addition, a close relationship between perennial Althaea and basal Alcea lineages is supported. Based on the evolutionary framework provided by recent molecular phylogenetic investigations, the following trends can be observed in the Malva alliance: long and narrow‐armed trichomes are primitive in relation to short and thick‐armed trichomes; dense indumentum coverage is primitive in relation to moderately dense or glabrous ones; presence of simple hairs on stem (particularly on leaves) is more advanced than their absence; spreading villous‐stellate and fascicled trichomes are more advanced than appressed stellate ones. Clavate trichomes, which were found exclusively in a few species of Alcea, should be considered as a derived state in relation to capitate ones, and they may provide a synapomorphy for the crown group of Alcea.

<p><strong><em>Mucuna guangxiensis</em></strong><strong>, a new species of <em>Mucuna</em> subg. <em>Macrocarpa</em> (Leguminosae-Papilionoideae) from China</strong></p>

Mucuna guangxiensis sp. nov. (Fabaceae), a woody liana species bearing pods up to 70 cm long, which is only known from Guangxi Province in China, is described and illustrated here. The new species is similar to Mucuna macrocarpa but differs from it by totally yellowish or greenish white corolla and more densely sericeous hairs on the abaxial surface; and also to Mucuna birdwoodiana but differs from it by the thinly papyraceous leaves, the dense indumentum on the abaxial surface of leaflets, and the longer legumes without paired robust wings at both margin. This new species should be a new member of Mucuna subg. Macrocarpa according to its long ovary, numerous seeds per legume and linear and long legumes with woody epicarp, and a detailed key of the subgenus is provided in this article.

Battenispermum hirsutum gen. et sp. nov., a new Early Cretaceous seed from Portugal with chlamydospermous organisation

A new genus and species, Battenispermum hirsutum, is described from the Early Cretaceous mesofossil flora of Catefica, Portugal. The new taxon is based on five ovulate structures with up to three seeds surrounded by an outer cup formed from partly fused bracts. The seeds are small, about 2.4–3.3 mm long and 1.0–1.6 mm wide, orthotropous with a chlamydospermous organisation. The nucellus is surrounded by a thin integument, a sclerenchymatic inner seed envelope and an additional outer envelope of four bracts, fused for most of their length. The seeds are three- or four-angled in transverse section and elliptical in lateral view with the free tips of the outer envelope forming short, apical projections around the micropyle. The outer surface of the inner seed envelope is almost smooth, while the abaxial surfaces of both inner and outer bracts of the compound ovulate structures are covered by a dense indumentum of long and stiff trichomes. Battenispermum hirsutum clearly belongs to the chlamydospermous BEG complex (Bennettitales-Erdtmanithecales-Gnetales), but it is distinguished from all previously described fossils by the presence of two distinct seed envelopes, a feature otherwise known only for extant Gnetum. The seeds of Battenispermum hirsutum differ, from those of extant Gnetum in other features, including the much simpler micropylar region.

Terminalia santisukiana (Combretaceae), a new species from North-Eastern Thailand

A new species of Terminalia, T. santisukiana (Combretaceae) from fresh water swamp forest in North-Eastern Thailand is described and illustrated. The new species is similar to Terminalia nigrovenulosa, having similar leaves with glands on the leaf margin near the base and paniculate inflorescences, but it is mainly distinguished by the loose panicles with dense indumentum on the flowers and the 4–5-winged fruits. It is also similar to Terminalia polyantha, having 4–5-winged fruits, but differs by the dense indumentum on the flowers and asymmetrical fruits.

<p><strong><em>Vicia brulloi</em></strong><strong> (Fabaceae), a new species from Sicily</strong></p>

Vicia brulloi, a new species from Peloritani range in NE Sicily, is described and illustrated. It is a perennial climbing liane linked to riparian woods, showing close relationship mainly with V. pisiformis, having a scattered European distribution. In particular, V. brulloi is a very rare and extremely localized species morphologically well distinct from V. pisiformis in several remarkable features, such as the dense indumentum covering the vegetative structures and calyces, the shape and size of flower pieces, pods, seeds, as well as seed testa micromorphology. Another relevant peculiarity of V. brulloi is the lower tooth of the calyx replaced by a green leafy appendix, character infrequent in legumes and hitherto never observed in other Vicia species, which clearly represents the residue of its ancestral foliar origin. The morphology, pollen grain and seed testa micromorphology, chromosome complement 2n = 2x = 12, seedling features, reproductive biology, biogeography, habitat, ecology, conservation status and taxonomic relationships of the new species are examined.

External water transport is more important than vascular transport in the extreme atmospheric epiphyte Tillandsia usneoides (Spanish moss).

Most epiphytic bromeliads, especially those in the genus Tillandsia, lack functional roots and rely on the absorption of water and nutrients by large, multicellular trichomes on the epidermal surfaces of leaves and stems. Another important function of these structures is the spread of water over the epidermal surface by capillary action between trichome "wings" and epidermal surface. Although critical for the ultimate absorption by these plants, understanding of this function of trichomes is primarily based on light microscope observations. To better understand this phenomenon, the distribution of water was followed by its attenuation of cold neutrons following application of H2 O to the cut end of Tillandsia usneoides shoots. Experiments confirmed the spread of added water on the external surfaces of this "atmospheric" epiphyte. In a morphologically and physiologically similar plant lacking epidermal trichomes, water added to the cut end of a shoot clearly moved via its internal xylem and not on its epidermis. Thus, in T.usneoides, water moves primarily by capillarity among the overlapping trichomes forming a dense indumentum on shoot surfaces, while internal vascular water movement is less likely. T.usneoides, occupying xeric microhabitats, benefits from reduction of water losses by low-shoot xylem hydraulic conductivities.

Novelties in Hyptidendron (Hyptidinae – Lamiaceae) from Brazil: A new species and a rediscovery

A new species, Hyptidendron roseum, from the Chapada dos Veadeiros region, Goias state, is described and illustrated. It can be distinguished from its congeners by the combination of inflorescences composed of a unilateral cymose structures, sessile to subsessile leaves, a ring of trichomes in the throat of the calyx tube, and a dense indumentum of white uniseriate trichomes covering much of the plant. The new species is compared with similar species such as H. unilaterale and H. albidum. New specimens of another species, H. unilaterale, formerly known only from the type, were identified in herbaria and collected in the field. Photos in vivo of this species are provided for the first time, accompanying a full description and an illustration. We assess its conservation status and comment on its distribution, ecological aspects, and identification.

Two New Species of Lauraceae from Ecuador

Two species of Lauraceae of Ecuador are described: Aniba magnifica and Ocotea granulosa. Aniba magnifica is characterized by its large vegetative parts and its dense strigulose indumentum on the underside of its young leaves, inflorescences and bracts. Ocotea granulosa is distinguishable by the dense strigulose indumentum, mixed with amorphous blackish granules on the underside of the young leaves, peduncles, pedicels and receptacles, and by a flat or slightly recurved leaf base.

Conspectus of Palicourea section Potaroenses (Rubiaceae), with a new species from French Guiana and a new combination

Context – The species of Psychotria subgen. Heteropsychotria have recently been transferred to Palicourea, following the results of molecular studies showing that they form a monophyletic group with the latter. This paper presents a conspectus of Palicourea sect. Potaroenses (formerly Psychotria subgen. Heteropsychotria sect. Potaroenses), discusses the characters of the section, and provides a key to the species. A new species recently collected in French Guiana is described and illustrated, and one new combination is included.Methods – This paper is based on direct study of herbarium material from BR, CAY, F, K, L, NY, U and US, and additional type specimens from F, K, MO, P, RB, and VEN were consulted online. Two of the species, including the new one, have also been studied in the field. Common practices of herbarium taxonomy have been applied.Results – Palicourea sect. Potaroenses is characterized by the capitate inflorescences surrounded by an involucre of 4–20 elliptic, yellow to red bracts, the leaves with lateral veins strongly ascending and almost reaching the margin, the long tubular calyx, the unusually long corolla tube for the genus, and the peculiar stipules, consisting of an internal sheath and two interpetiolar pieces connate to the sheath by their central part. The section includes eight species: Palicourea aetantha (Sandwith) Delprete & J.H.Kirkbr., P. fanshawei (Standl.) Delprete & J.H.Kirkbr., P. formosissima (Steyerm.) Delprete & O.Lachenaud, P. phaneroneura (Standl.) Borhidi, P. potaroensis (Sandwith) Delprete & J.H.Kirkbr., P. psittacina (Steyerm.) Delprete & J.H.Kirkbr., P. spectabilis (Steyerm.) Borhidi, and the new species P. aurantiosplendens O.Lachenaud & Delprete. The latter is most similar to P. psittacina, from which it can be separated by the dense patent indumentum of the stems, calyx lobes, and inner side of the bracts, and the smaller size of the latter; it also resembles P. spectabilis and P. formosissima, but differs in having the stipules with four lobes on each side (vs. two), the bracts nearly glabrous outside (vs. densely hirsute on both sides) and the calyx lobes much more pubescent than the tube (vs. the calyx uniformly hairy). It is only known from a small area on the upper Sinnamary River, north-central French Guiana, and is evaluated as Endangered (EN D1) according to IUCN criteria.