<abstract xmlns="http://www.w3.org/1999/xhtml"><p>Hybrids between <italic>Quercus robur</italic> and <italic>Q. petraea</italic> have been a sought topic of many studies in Europe during the last decades. Here, leaf and fruit morphology were studied in five oak stands where both species occur naturally intermixed. The stands are relicts of old, possibly medieval coppice wood. Twenty two leaf characters and nine fruit characters were assessed on three leaves and three fruits per tree and for thirty trees per stand. A principal component analysis (PCA) resulted in a bimodal distribution with restricted overlap along the first component when both leaf and fruit data were processed together. For leaf and fruit data separately, the analysis produced only continuous clusters of trees. Two types of putative hybrids can be defined that either show a petiole length of the leaf (PL) according to <italic>Q. robur</italic> and a petiole length of the fruit (FP1) according to <italic>Q. petraea</italic>, or vice versa. These hybrids cluster within both groups of the PCA analysis, but not all are situated close to or in the intermediate area between the groups. A lowered mean relative number of developed acorns in the hybrid groups in comparison to their putative maternal parent, based on the assumption of matroclinal inheritance of PL, is observed. This might indicate a reduced ability for successful fertilisation in the hybrids. These results suggest the presence of putative hybrids and introgressed forms within the morphological distinct <italic>Q. robur</italic> and <italic>Q. petraea</italic> groups and argument for a taxonomically defined <italic>Q. x rosacea</italic> based on PL and FP1 limits.</p></abstract>

Hybrids between Quercus robur and Q. petraea have been a sought topic of many studies in Europe during the last decades. Here, leaf and fruit morphology were studied in five oak stands where both species occur naturally intermixed. The stands are relicts of old, possibly medieval coppice wood. Twenty two leaf characters and nine fruit characters were assessed on three leaves and three fruits per tree and for thirty trees per stand. A principal component analysis (PCA) resulted in a bimodal distribution with restricted overlap along the first component when both leaf and fruit data were processed together. For leaf and fruit data separately, the analysis produced only continuous clusters of trees. Two types of putative hybrids can be defined that either show a petiole length of the leaf (PL) according to Q. robur and a petiole length of the fruit (FP1) according to Q. petraea, or vice versa. These hybrids cluster within both groups of the PCA analysis, but not all are situated close to or in the intermediate area between the groups. A lowered mean relative number of developed acorns in the hybrid groups in comparison to their putative maternal parent, based on the assumption of matroclinal inheritance of PL, is observed. This might indicate a reduced ability for successful fertilisation in the hybrids. These results suggest the presence of putative hybrids and introgressed forms within the morphological distinct Q. robur and Q. petraea groups and argument for a taxonomically defined Q. x rosacea based on PL and FP1 limits.

A combination of fruit and leaf morphology enables taxonomic classification of the complex <italic>Q. robur</italic> L. – <italic>Q. x rosacea</italic> Bechst. – <italic>Q. petraea</italic> (Matt.) Liebl. in autochthonous stands in Flanders

Silvae Genetica

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A combination of fruit and leaf morphology enables taxonomic classification of the complex  L. –  Bechst. –  (Matt.) Liebl. in autochthonous stands in Flanders

Hybrids between Quercus robur and Q. petraea have been a sought topic of many studies in Europe during the last decades. Here, leaf and fruit morphology were...

A combination of fruit and leaf morphology enables taxonomic classification of the complex Q. robur L. – Q. x rosacea Bechst. – Q. petraea (Matt.) Liebl. in autochthonous stands in Flanders

Published Online: Aug 05, 2017

Page range: 139 - 148

Received: Jul 27, 2010

DOI: https://doi.org/10.1515/sg-2011-0019

Keywords
hybridisation, leaf and fruit morphology, number of undeveloped acorns, taxonomy

© 2011 Kristine Vander Mijnsbrugge et al., published by De Gruyter Open

This work is licensed under the Creative Commons Attribution-NonCommercial-NoDerivatives 3.0 License.

A combination of fruit and leaf morphology enables taxonomic classification of the complex Q. robur L. – Q. x rosacea Bechst. – Q. petraea (Matt.) Liebl. in autochthonous stands in Flanders

Published Online: Aug 05, 2017

Page range: 139 - 148

Received: Jul 27, 2010

DOI: https://doi.org/10.1515/sg-2011-0019

Keywordshybridisation, leaf and fruit morphology, number of undeveloped acorns, taxonomy

© 2011 Kristine Vander Mijnsbrugge et al., published by De Gruyter Open

This work is licensed under the Creative Commons Attribution-NonCommercial-NoDerivatives 3.0 License.

Keywords
hybridisation, leaf and fruit morphology, number of undeveloped acorns, taxonomy