Search results for "ACEA"
showing 10 items of 2814 documents
Integrative taxonomy sheds light on an old problem: theUlota crispacomplex (Orthotrichaceae, Musci)
2016
The combined use of morphological and molecular analyses has been proven to be useful in resolving taxonomic complexes with hidden diversity. In bryology, however, integrative taxonomy has rarely been employed to revisit relevant old, unresolved problems. One of these classical controversies is whether the Ulota crispa complex comprises one or three species. To elucidate this, an exhaustive morphological revision, based on numerous herbarium and fresh specimens from most of the Holarctic areas in which U. crispa has been reported, and molecular analyses, using one nuclear (ITS2) and three plastid (trnG, trnL-trnF, atpB-rbcL) loci on a selection of representative specimens, have been perform…
Cladode growth dynamics in Opuntia ficus-indica under drought
2016
Abstract Cactus pear (Opuntia ficus-indica L. Miller) is a CAM plant with an extraordinary capacity to store water in its succulent stems (cladodes). However, the daily variations of cladode thickness is unknown. Studying cladode thickness fluctuations may be useful for the early prediction of plant dehydration stress. The objective of this study was to determine if age, water availability and temperature influence diel cladode shrinkage and enlargement dynamics in cactus pear. The experiment was conducted in a greenhouse from April to July 2014, using cactus pear plants, equally split into irrigated and unirrigated treatments, and unrooted cladodes detached from mother plants. Soil moistur…
Nectar protection in arid-adapted flowers of Zygophyllaceae-Zygophylloideae
2018
Abstract The survival of plants in arid areas depends on efficient adaptation to extreme environments. The protection against nectar loss is an important challenge for flowers in arid environments. Flowers of arid-adapted Zygophyllaceae subfamily Zygophylloideae are characterized by a peculiar structure called staminal scales (SS). The special arrangement of SS around the perigynous disc nectary (DN) suggests their adaptive function for protection against nectar loss. We aim to test the protective function of SS and to understand the synorganised evolution of SS and DN in relation to nectar protection. We, first, manipulate flowers by removal of SS in two representatives of Zygophylloideae.…
Decoupling of light intensity effects on the growth and development of C3 and C4 weed species through sucrose supplementation
2002
Light availability has a profound effect on plant growth and development. One of the ways to study the effects of light intensity on plant growth and development without the confounding problem of photosynthate availability is sucrose injection/supplementation. A greenhouse experiment was conducted to evaluate the effects of light levels (0% and 75% shade) and sucrose injection (distilled water or 150 g sucrose l(-1)) on three weed species: redroot pigweed (Amaranthus retroflexus L., C4), lambsquarters (Chenopodium album L., C3) and velvetleaf (Abutilon theophrasti Medic., C3). The average total sucrose uptake was 7.6 and 5.9 g per plant for 0% and 75% shading, respectively, representing 47…
Can sucrose content in the phloem sap reaching field pea seeds (Pisum sativum L.) be an accurate indicator of seed growth potential ?
2003
The composition of the translocates reaching the seeds of pea plants having various nitrogen (N) nutrition regimes was investigated under field situations. Sucrose flow in the phloem sap increased with the node number, but was not significantly different between N nutrition levels. Because N deficiency reduced the number of flowering nodes and the number of seeds per pod, the sucrose flow bleeding from cut peduncles was divided by the number of seeds to give the amount of assimilates available per seed. The sucrose concentration in phloem sap supplied to seeds at the upper nodes was higher than that at the lower nodes. The flow of sucrose delivered to the seeds during the cell division peri…
Phylogeny, biogeography and systematics of Dysphanieae (Amaranthaceae)
2021
After a rather turbulent taxonomic history, Dysphanieae (Chenopodioideae, Amaranthaceae) were established to contain five genera, four of which are monospecific (Cycloloma, Neomonolepis, Suckleya, Teloxys) and geographically restricted, and the fifth genus, Dysphania, having a nearly worldwide distribution and comprising ca. 50 species. This study investigates the phylogeny, biogeography and taxonomy of Dysphanieae. We studied specimens from 32 herbaria to infer morphological differences and distribution areas of the species and sampled 121 accessions representing 39 accepted species of the tribe for molecular phylogenetic analyses. The molecular phylogeny tested generic relationships of th…
Molecular systematics in the acanthocephalan genus Echinorhynchus (sensu lato) in northern Europe
1994
SUMMARYNew biological species and high levels of inter- and intraspecific genetic divergence were discovered in an allozyme study of some North European members of the acanthocephalan genus Echinorhynchus (sensu lato), parasites of fish and malacostracan crustaceans. (i) A strong differentiation between the marine E. gadi and the fresh- and brackish-water E. salmonis (genetic identity I ≃ 0) supports a generic distinction between these taxa; however, the subdivision would not entirely concur with the concepts of Echinorhynchus (sensu stricto) and Metechinorhynchus suggested earlier. (ii) Samples of E. gadi from the Baltic, Norwegian and North Seas included three distinct, partially sympatri…
Phylogeny and systematics of African Melastomateae (Melastomataceae)
2017
Melastomateae are the most species-rich (185 spp./13 gen.) and morphologically diverse tribe within the African Melastomataceae. In this study we present the first in-depth phylogenetic analysis of African Melastomateae using sequences generated from one nuclear (nrITS) and two plastid spacers (accD-psaI, psbK-psbL) sampling 183 accessions representing 75 African, 10 Madagascan and 7 Asian species and a broad outgroup sampling. We infer phylogenetic relationships using maximum likelihood, maximum parsimony and Bayesian approaches and propose a revised generic classification of African Melastomateae based on our molecular trees in combination with a careful reassessment of morphological vari…
The genus isoetes (Isoetaceae): A provisional checklist of the accepted and unresolved taxa
2016
Isoetes is a widely distributed lycophyte genus of at least 200 species occurring in diverse habitats. The species can be difficult to identify because Isoetes, with its apparent simplicity of form and conserved morphology, provides few diagnostic features to reliably distinguish its species. The last worldwide monograph, published nearly a century ago, listed 77 taxa. The first step in producing a flora or monograph of all known species of a genus is to compile a list of the acceptable species names. The list presented here is a compilation of 192 accepted names representing taxa from regions around the world: chromosome numbers were assigned to 101 of them, with polyploidy settled on 46.7…