The genus Cornus encompasses a wide range of attractive wild taxa, often used as ornamental plants in landscaping. The aim of this investigation was to highlight the quantitative and qualitative diversity within endocarp morphological traits apparent among 15 Cornus species representing different geographical and phylogenetic groups. Seventeen morphological traits of Cornus endocarps were evaluated in 185 Cornus collections originating from the Northern Hemisphere. To explore structure in our dataset and reduce its complexity, several multivariate statistical analyses (i.e., PCA, MANOVA, ANOVA, and analysis of contingency tables) were employed. Two clearly distinct sample groups were observed after the PCA, reflecting a high level of taxonomic division of analyzed species, i.e., subgenera: Mesomora and Kraniopsis. The study highlights qualitative and/or quantitative characters that partitioned (1) groups of species or some individual species, (2) geographical groups, and (3) cultivated and wild collections. Results of trait validation are presented in identification keys. A partial congruence was detected between our results and a currently available species level phylogeny of the genus Cornus. The morphology of Cornus endocarps is of taxonomic importance and provides a key for species identification. The existence of only subtle morphological differences between some closely related taxa does not sufficiently explain their species status. The applicability of our results to the previously published morphological records is limited, mainly due to vague terminology. Considerably more work will need to be done to determine the effect of cultivation on qualitative reproductive traits of Cornus species.
Cornus mas L., C. officinalis Sieb. et Zucc. and their putative interspecific hybrid specimens were examined in order to describe their morphological, anatomical and genetic differentiation. Petiole length, number of leaf veins, pedicel and bract length, stone size, thickness of pericarp layers, the size and number of locules and the number of cavities were measured. Pedicels and bracts were shown to be significantly longer for C. mas (7.22 and 6.95 mm) and for the putative hybrid (9.11 and 6.61 mm) than for C. officinalis (6.86 and 5.81 mm, respectively). Average values of stone width and thickness, exocarp and mesocarp thickness, the number of cavities in the endocarp obtained for the putative hybrid differed significantly in comparison to C. mas and were similar to C. officinalis. Genotypes of the examined species were evaluated for genetic relationships using random amplified polymorphic DNA (RAPD) markers. Initial screening of the bulks of C. mas and C. officinalis compared with their putative hybrid using 72 decamer random primers resulted in the identification of 24 primers differentiating both species and their putative hybrid and showing reliable polymorphisms. Among a total of 485 amplified fragments, 89.7% were polymorphic, 18.8% were specific to C. mas individuals, and 18.6% were specific to the individuals of C. officinalis. In obtained profiles of the examined hybrid individual specific products absent in the genotypes of both parents were observed. The phylogenetic tree revealed two separate clusters including C. mas and C. officinalis accessions, respectively. The biggest genetic distance was observed for hybrid specimens, although the hybrid belonged to the C. mas cluster.
A b s t r a c tThe presence of 395 species of vascular flora at four rarely used cemeteries within the Poznań city was confirmed in 2010. Apart from naturally occurring species, cultivated species were noted equally. Among species appearing spontaneously between the graves, species new for the flora of Poland: Chionodoxa forbesii, Ch. luciliae, Puschkinia scilloides, new for the flora of Wielkopolska: Bidens ferulifolius, Hyacinthoides hispanica and new for the flora of Poznań: Erigeron ramosus, Lilium bulbiferum, Pimpinella nigra, Poa subcaerulea, Veronica hederifolia s.s., were recorded. Names of taxa originating from cultivation are underlined.
The genus Cornus is known for its complicated taxonomy and extreme polymorphism. Currently, dogwoods are classified into four morphological groups reflected in four phylogenetic clades: blue- or white-fruited dogwoods (BW), cornelian cherries (CC), big-bracted dogwoods (BB), and dwarf dogwoods (DW). The present study is a continuation of a series of papers that started with the examination of the endocarp morphological diversity among BW species. The endocarps of 22 Cornus species were studied according to their morphology, internal structure, and sculpture; the aim was to evaluate the taxonomic importance of the examined characters and check whether endocarp differentiation supports the published phylogenies, according to which the relationships within the genus are indicated as (BW(CC(DW-BB))). Among the quantitative characters, the endocarp’s length, thickness, and width, its length/width ratio, and the number of vascular bundles on its surface were considered taxonomically important. Regarding the qualitative characters, the taxonomic significance of the stone shape, the endocarp apex and base outline, the position of vascular bundles on the endocarp surface, and the presence of the apical cavity and distinct furrow on the endocarp side walls was proved. Additionally, the uniform qualitative characters having a 100% share of a given character state were identified. Cornelian cherries and dwarf dogwoods were characterised by the presence of four uniform characters. In the big-bracted group, two uniform characters were found. Blue- or white-fruited species were the most heterogeneous, with no uniform characters. Regarding the endocarp’s internal structure, the presence of secretory cavities in the endocarp wall and in the septa, the presence of crystals in the outer endocarp, the number of cell layers in the transition sclereid zone, and the primary and secondary sculptures were found to be taxonomically significant. Additionally, the comparative analyses of dogwood endocarps found the following parameters to be useful: the germination valve thickness, the ratio of endocarp wall thickness to endocarp diameter, and the septum’s width and structure. Due to the great differentiation of the examined characters, it was difficult to verify the research hypothesis unambiguously. The calculated similarity coefficients of the endocarps’ qualitative and quantitative characters revealed the highest morphological similarity of endocarps between DW and BB groups, supporting the phylogenetic relationships based on molecular evidence. The number of vascular bundles on the endocarp surface was the character that supported this similarity the most. The similarity coefficients calculated separately for qualitative characters showed the closest similarity between groups CC-DW. However, these results do not directly reflect any of the published phylogenies.
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