Allelopathic vs. autotoxic potential of a grassland weed—evidence from a seed germination experiment

ABSTRACT

Background: Mechanisms affecting invasiveness of non-indigenous species have received much attention. Few studies have investigated invasions by native plants. Invasive native species such as common ragwort (Jacobaea vulgaris) may become noxious weeds. They challenge farming and nature conservation by outcompeting fodder plants or rare herbs. One mechanism that can result in outcompeting plants is by allelopathy.

Aim: We evaluated the potential of J. vulgaris to suppress germination in common and rare grassland species by allelopathy.

Methods: In a germination chamber experiment, we exposed 22 species and J. vulgaris itself to ragwort leachate. We controlled for osmotic effects by germination tests in mannitol solution and water. We assessed germination percentage—time —synchrony and radicle length.

Results: Leachate reduced germination percentage, germination time, synchrony and radicle length. These effects were similar for J. vulgaris, indicating autotoxicity. Rare species germinated less than common species but were not more sensitive to the phytotoxic effects of J. vulgaris. Restraining effects of the leachate were similar to the mere osmotic effect.

Conclusion: Our results question allelopathy as the main driving mechanism behind J. vulgaris gaining dominance. However, the impact of J. vulgaris might depend on the composition of the invaded plant community due to species-specific effects.     

New species of Justicia (Acanthaceae) from the Guianas

Four new species,Justicia oldemanii, J. mcdowellii, J. wilhelminensis, andJ. prevostiae are described, illustrated, and compared with their closest relatives. A key to species ofJusticia from the Guianas is also provided.     

List of Members

Abstract

Bazzania okaritana, a new species from South Island, New Zealand, is described and illustrated, and a comparison with similar species is made. The new species is most similar to Bazzania hochstetteri (Reichardt) E.A. Hodgs. and Bazzania exempta J.J. Engel, but differs in several respects from both these species.     

Calymperes schmidtii Broth. in J. Schmidt and C. subintegrum Broth. in J. Schmidt,two distinct species from Malesia

Abstract

Calymperes schmidtii Broth. in J. Schmidt and C. subintegrum Broth. in J. Schmidt, hitherto regarded as conspecific, are shown to represent distinct species.     

Three new species of Philocorydoras Suriano, 1986 (Monogenoidea: Dactylogyridae) infecting the gills of callichthyids (Actinopterygii: Callichthyidae) from the Peruvian Amazonia

During a research on gill ectoparasites of callichthyids fishes from the Peruvian Amazonia, the following monogenoideans were found: Philocorydoras peruensis n. sp. from Corydoras splendens (Castelnau); Philocorydoras multiradiatus n. sp. and Philocorydoras jumboi n. sp. from Brochis multiradiatus (Orcés, V.). All new species described herein are mainly differentiated from their congeners based on the morphology of the copulatory complex. In P. peruensis n. sp. the cirrus is “J”-like shaped tube slightly tilted to one side, while in P. jumboi n. sp. is “J”-like shaped tube in a straight position and in P. multiradiatus n. sp. the cirrus is an arced tube with inflated base and distally narrow. Brochis (Orcés, V.) represents a new genus hosting species of Philocorydoras. All new species presented in this work represent the first species of Philocorydoras reported for Peru.

     

Jacquinia pauciflora (Theophrastaceae), a new species from Puerto Rico

A new species,Jacquinia pauciflora, is described from subtropical moist forest on karst hills (mogotes) in northwestern Puerto Rico.Jacquinia pauciflora is similar toJ. stenophylla Urban, from which it differs in several floral and leaf characters, but is possibly most closely related toJ. umbellata A. DC. A key to the species ofJacquinia occurring in Puerto Rico is provided.     

Jaltomata II: new combinations for five South American species (Solanaceae)

The following species, originally described in the genusSaracha Ruiz & Pav., are transferred toJaltomata, in accordance with contemporary generic boundaries.Jaltomata auriculata (Miers) Mione is distributed from Venezuela to Peru;J. contorta (Ruiz & Pav.) Mione andJ. diversa (J. F. Macbr.) Mione both occur in Peru;J. herrerae (C. V. Morton) Mione is distributed in Peru and Bolivia;J. nitida (Bitter) Mione occurs in Venezuela.     

Hybridisation in Jacobaea – characterisation of hybrids between Jacobaea aquatica and J. vulgaris in Austria

Background: Hybridisation in Senecio/Jacobaea is frequent and of significance in speciation and evolution. Moreover, these genera are model systems for studying the evolution of pyrrolizidine alkaloids (PAs). Hybrids between Jacobaea aquatica and J. vulgaris have been reported from north-western Europe.

Aims: Our aim was to determine whether hybrids between Jacobaea aquatica and J. vulgaris also occurred in Austria, and if these hybrids could be responsible for the presumed increase of J. aquatica-like plants in this part of Europe. Furthermore, we tested if such hybrids showed an altered PA spectrum compared with parental species.

Methods: We used amplified fragment length polymorphisms (AFLPs) to analyse genetic diversity and structure, and gas chromatography–mass spectrometry (GC–MS) to identify PAs.

Results: We were able to identify genetically one hybrid population adjacent to a large J. aquatica population. The AFLP phenotypes of hybrids demonstrated a closer relationship to J. aquatica, suggesting frequent backcrossing. All hybrid individuals contained the same set of PAs as the parental species, but in differing amounts, plus four additional PAs, one of which may be novel.

Conclusions: Although hybridisation in Jacobaea is common, we were able to confirm only one hybrid population in Austria. Therefore, it seems unlikely that hybridisation plays a role in the presumed increase of J. aquatica in this area.     

Fissidens viridulus Wahlenb. and F. minutulus Sull.

Abstract

A new species of Pseudocrossidium R.S.Williams, P. exiguum M.J.Cano &; J.A.Jiménez, is described from South America (Argentina, Brazil and Peru). The species is distinguished morphologically by its lingulate to oblong-ovate leaves, leaf marginal cells not or scarcely differentiated from inner, costa ending below apex or percurrent, and semicircular to elliptical in cross-section with two guide cells, scarcely differentiated perichaetial leaves and peristome of short and straight teeth. Drawings and light microscope photographs of the new species are provided. The principal distinctive characters that separate it from the nearest species of Pseudocrossidium and related genera are discussed.     

Pseudocrossidium perpapillosum (Pottiaceae) a new species from South America

Abstract

Pseudocrossidium perpapillosum M.J.Cano & J.A.Jiménez is described and illustrated as a new South American species from Argentina and Chile. It differs from other species of Pseudocrossidium R.S.Williams by the costa excurrent in an awn, elliptical in cross-section, with 4–5(6) guide cells, marginal laminal cells differentiated with rounded, thin-walled and papillose cells, paracostal distal cells with 1–2(4) bi- to quadrifurcate, long papillae, and perichaetial leaves differentiated.     

First record of Caulerpa lentillifera J. Agardh (Bryopsidales,Chlorophyta) from China

ABSTRACT

An edible green algal species Caulerpa lentillifera J. Agardh is reported from China for the first time. The species was collected from the southwest of Hainan Island and morphologically identified to be C. lentillifera based on the grape-like branches arising from cylindrical stolons. Phylogenetic analysis using tufA and rbcL DNA sequences also confirmed the monophyly of C. lentillifera-microphysa clade.     

A new synthetic species of Cucumis (Cucurbitaceae) from interspecific hybridization and chromosome doubling

A new synthetic species,Cucumis hytivus J.-F. Chen & J. H. Kirkbr. (2n=38), obtained by doubling the number of chromosomes in the sterile interspecific F₁ hybrid (2n=19) betweenC. sativus L. (2n=14) andC. hystrix Chakr. (2n=24), is described.     

Hybridity as a main evolutionary force in the genus Gagea Salisb. (Liliaceae)

Abstract

The important role of hybridity in the evolution of the genus Gagea is becoming clear, through morphological, karyological and molecular evidences. Several species were recently inferred or hypothesized to be of hybrid origin; especially in sect. Didymobulbos, sect. Fistulosae and sect. Gagea. Representative case studies, such as G. luberonensis J.-M. Tison, G. polidorii J.-M. Tison and G. pomeranica Ruthe, are presented and discussed.

Since many Gagea species show very reduced or null sexual reproduction vs. a massive vegetative propagation, there are several problems in distinguishing hybrids from hybridogenous species in this genus. The actual trend is to consider them at specific level because of their ability to stabilize, at least through vegetative propagation by bulblets and/or bulbils.     

A contribution to the taxonomy of Piptadenia (Mimosaceae) in South America

Four new species ofPiptadenia are described:P. anolidurus (from Amazonian Ecuador, Peru and Brazil),P. buchtienii (from trans-Andean Bolivia),P. cuzcoënsis (from southern Peru), andP. imatacae (from Venezuelan Guayana); andP. adiantoides var.peruviana J. F. Macbr. is raised in rank toP. peruviana. In relation toP. imatacae the transfer ofP. uaupensis Benth. andP. floribunda Kleinhoonte toAdenopodia Presl is shown to be ill-advised. The affinities of each new species are discussed and critical characters are illustrated.Mimosa tessmanii Harms is newly synonymized withP. uaupensis.

     

Rhodymenia delicatula P.J.L. Dangeard (Rhodophyta,Rhodymeniales) en Méditerranée

Abstract

Presence of Rhodymenia delicatula P.J.L. Dangeard in the Mediterranean. - The presence of Rhodymenia delicatula P.J.L. Dangeard (Rhodophyta, Rhodymeniales) in the southern Thyrrhenian sea is reported. Both cystocarpic and tetrasporic individuals have been collected. Anatomical features of the reproductive structures, as well as the position of these on the thallus allowed the identification of this species formerly known for the Atlantic coasts of Morocco and British Isles.     

A small collection of mosses from Sulawesi

Abstract

A collection of mosses made by Mr M. J. E. Coode in Sulawesi, comprizing 37 species, is reported upon. Five species appear to be unrecorded for this still bryologically littleknown island. Taxitheli'um capillarisetum appears to be the first gathering since the type collection (in New Guinea).     

Atlantic bryophytes in Scotland

Summary

A brief overview is given of the importance of Scotland for Atlantic bryophytes within Europe and worldwide. The life strategies of Atlantic species are discussed and the main habitats of Atlantic bryophytes listed. A consideration of the use of distribution data to identify ‘hotspots’ and sites for conservation is made. Grimmia britannica A.J.E. Smith and Marsupella profunda Lindb. are added to the list of Atlantic species in Britain and Ireland.     

Grias longirachis (Lecythidaceae), a new species from northwestern Ecuador

A new species,Grias longirachis S. A. Mori & J. L. Clark, with enclosed calyx in bud and unusually long inflorescence rachises, is described based on collections from northwestern Ecuador. A key to the species ofGrias is provided.     

The moss genus Leptobryum and the identity of Pohlia integra

Abstract

Leptobryum Wilson (Bryaceae) consists of two species, viz., Leptobryum pyriforme (Hedw.) Wilson and L. wilsonii (Mitt.) Broth. Pohlia integra (Cardot) A.J.Shaw and three other species of Leptobryum, viz., L. escomelii Thér., L. pottiaceum Dusén, L. stellatum (Herzog) Broth. are reduced to synonomy under L. wilsonii. L. sericeum Kindb. is considered a doubtful species because no specimen could be located.