Veit Dörken - Academia.edu (original) (raw)
Papers by Veit Dörken
Der Palmengarten, Dec 30, 2015
2. Systematik und Verbreitung Halesia gehört zur Familie der Styracaceae (Storaxgewächse), zu den... more 2. Systematik und Verbreitung Halesia gehört zur Familie der Styracaceae (Storaxgewächse), zu denen z. B. auch der Storaxbaum (Styrax officinalis, Lieferant des Storaxharzes) gestellt wird. Halesia hat ein disjunktes Schneeglöckchenbäume
Der Palmengarten, Nov 25, 2018
The golden larch (Pseudolarix amabilis) is an ornamental eastern Asian conifer with a long evolut... more The golden larch (Pseudolarix amabilis) is an ornamental eastern Asian conifer with a long evolutionary history. It is one of the few deciduous gymnosperms which sheds its leaves after an intensive golden autumnal coloring. Zusammenfassung Die Goldlärche (Pseudolarix amabilis) ist eine ostasiatische Konifere mit einer langen evolutionären Geschichte. Den volkstümlichen Namen kann man erst im Herbst verstehen, wenn sich die Nadeln vor dem Abwerfen in ihrer prächtig leuchtenden Herbstfärbung präsentieren.
Svensk Botanisk Tidskrift, 2015
Der Palmengarten, 2014
Die Sizilien-Tanne (Abies nebrodensis) ist mit lediglich nur noch ca. 30 Individuen am Naturstand... more Die Sizilien-Tanne (Abies nebrodensis) ist mit lediglich nur noch ca. 30 Individuen am Naturstandort eine der seltensten und am meisten bedrohten Koniferen-Arten der Welt. Im Forstarboretum Freiburg-Gunterstal, Deutschland, wurde eine Flache von 0,3 ha als Erhaltungskultur angelegt.
Trees-structure and Function, Jun 16, 2023
Key message We examined the leaf structure of two basal Cupressus species with a distinct leaf di... more Key message We examined the leaf structure of two basal Cupressus species with a distinct leaf dimorphism. Some foliar features are regarded as ancestral and it is suggested that drought adaptation was one of the important ecological drivers in the evolution of the Cupressus genus. Abstract Leaf morphology and anatomy of two Cupressus species, C. nootkatensis and C. vietnamensis, were investigated with classical paraffin technique and scanning electron microscopy (SEM). Like all Cupressus species these two are characterised by a dramatic change in the foliage. Juveniles have needle leaves first before they change abruptly to the mature scale leaf type. In C. vietnamensis, needle-leaved shoots occur next to scale-leaved ones even on mature trees, which is unique among today´s Cupressus species. Adults of C. nootkatensis develop only scale leaves throughout. In both taxa, the scale leaves show a distinct dimorphism between lateral and facial leaves, which are arranged in a flat spray; the foliate shoots are two-dimensionally flattened. These scale leaves show several xeromorphic features; e.g. strongly reduced leaf size, stomata with high, collar-like Florin rings, the presence of a distinct hypodermis as a continuous layer and well-developed transfusion tissue. The needle leaf type is found in Cunninghamia which is the basal member of the Cupressaceae and so is regarded as the ancestral condition and scale leaves as a derived one. Scale leaves are found in all the members of the cupressoid clade even within the basal taxa from mesic habitats. However scale leaves are a preadaptation to survival under xeric conditions and they are likely an evolutionary driver of the radiation of Cupressus into arid environments, as has also been the case in genera such a Callitris.
Der Palmengarten, Dec 30, 2014
Lychee (Litchi chinensis) and rambutan (Nephelium lappaceum) are evergreen tropical trees. Their ... more Lychee (Litchi chinensis) and rambutan (Nephelium lappaceum) are evergreen tropical trees. Their delicious fruits are edible. Morphology, biology and use of these species are outlined. Zusammenfassung Litchi (Litchi chinensis) und Rambutan (Nephelium lappaceum) sind immergrüne tropische Bäume. Ihre wohlschmeckenden Früchte sind essbar. Morphologie, Biologie und Verwendung werden vorgestellt.
Zweifelsohne gehört der Ginkgo auch in Mitteleuropa zu den bekanntesten fremdländischen Baumarten... more Zweifelsohne gehört der Ginkgo auch in Mitteleuropa zu den bekanntesten fremdländischen Baumarten und erst Recht zu den berühmtesten sog. "lebenden Fossilien". Wer kennt nicht seine ungewöhnlichen, an der Spitze meist zweigeteilten Blätter (Abb. 1), die regelmäßig in der Werbung für Medikamente gegen das Altern oder auch in Form von Broschen zu sehen sind? Besonders im Herbst zum Zeitpunkt der intensiven gelben Herbstfärbung als auch nach dem Blattabwurf, wenn die leuchtend silbrig-gelben Samen noch am Baum hängen, fallen die Bäume besonders auf (Abb. 2). Nachfolgend wird die Paläobotanik, Systematik und Morphologie dieser einzigartigen Gattung vorgestellt.
Zaubernuss-Arten (Hamamelis spp.) sind in Mitteleuropa häufig gepflanzte Ziergehölze und stellen ... more Zaubernuss-Arten (Hamamelis spp.) sind in Mitteleuropa häufig gepflanzte Ziergehölze und stellen wichtige Solitärsträucher in Garten-und Parkanlagen dar. Im Sommer sind sie eher unauffällig, im Herbst aber zeigen sie eine spektakuläre Herbstfärbung und im Winter (Ausnahme H. virginiana) bezaubern sie durch ihren sehr frühen Blütezeitpunkt (Abb. 1 & 2). Möglicherweise haben sie daher auch ihren deutschen Namen.
Trees-structure and Function, Jun 16, 2023
Key message We examined leaves of a suite of microphyllous woody plants and describe a little-kno... more Key message We examined leaves of a suite of microphyllous woody plants and describe a little-known form of leaf peltation for the first time and also investigate strongly reflexed leaves in two distantly related lineages. Abstract Plants cope with a range of environmental conditions, especially related to water relations, and have developed an array of physiological and structural solutions to maintain a functional water balance. There has been considerable recent work on physiological solutions to water deficit but little attention paid to leaf characteristics. In many species there is a change in leaf form from seedlings to adults. We examine such changes in several small-leaved species from the distantly related Asteraceae and Myrtaceae, some of which develop micropeltate or reflexed leaves as adults. All are native to dry or seasonally dry sites. Three major morphological groups were recognised as follows: (1) leaves erect, nonpeltate and scalelike (Ozothamnus hookeri), (2) leaves erect and peltate (Phaenocoma prolifera, Regelia inops), (3) Leaves reflexed (Olearia lepidophylla, Ozothamnus scutellifolius, Ozothamnus reflexifolius, Melaleuca diosmifolia). The microphyllous peltation in P. prolifera and R. inops in the absence of a meristematic fusion/bridge differs from typically peltate leaves. These smallleaved taxa occur in open, high light environments which are very different from the mesic, shaded understorey habitats of typical peltate-leaved plants. Many small-leaved species have leaves closely appressed to the stem and often with recurved margins. The erect leaves are functionally similar to reflexed leaves. Environmental filtering leads to superficially similar plant forms that may have somewhat different ontological origins. Such morphological forms are examples of convergent evolution in distantly related species but within each family are likely phylogenetically related.
Trees-structure and Function, Mar 26, 2018
Key message In Melaleuca minutifolia mature leaves are linear, in Melaleuca micromera scale-like ... more Key message In Melaleuca minutifolia mature leaves are linear, in Melaleuca micromera scale-like and peltate. This peltation is caused by swollen basal mesophyll without meristematic fusions. Thus, a novel peltation strategy is described. Abstract The foliar change of two Australian Melaleuca species (Myrtaceae) was investigated in different ontogenetic stages from cotyledons up to the mature leaf types. In both taxa (M. minutifolia and M. micromera), a strong leaf reduction occurs. While in M. minutifolia the mature leaf type is linear, inverse bifacial and strongly adpressed to the shoot axis, in M. micromera it is scale-like, aequifacial, minute and peltate. The mature leaf type of M. micromera is one of the rare examples of peltation among woody species. The ontogenetic studies on the mature peltate leaf type of M. micromera showed that a shield-like leaf base and typical peltate leaf morphology can be formed, not exclusively by meristematic fusions, as is the case for peltate leaves in the classical sense, but instead by strongly swollen mesophyll, particularly in the basal part of the leaf. While most species with peltate leaves are herbaceous perennials from very moist to aquatic habitats and lack reduced leaves, the four Melaleuca species known with the M. micromera type of peltation are from habitats showing either seasonal water stress, soil infertility or both and all show extreme leaf reduction. Given our morpho-anatomical data, it is clear that, as well as the classical type of peltation, a novel, second strategy for achieving peltation needs to be distinguished. The two types are correlated with quite different environmental conditions.
Der Palmengarten, Dec 30, 2015
2. Systematik und Verbreitung Halesia gehört zur Familie der Styracaceae (Storaxgewächse), zu den... more 2. Systematik und Verbreitung Halesia gehört zur Familie der Styracaceae (Storaxgewächse), zu denen z. B. auch der Storaxbaum (Styrax officinalis, Lieferant des Storaxharzes) gestellt wird. Halesia hat ein disjunktes Schneeglöckchenbäume
Der Palmengarten, Nov 25, 2018
The golden larch (Pseudolarix amabilis) is an ornamental eastern Asian conifer with a long evolut... more The golden larch (Pseudolarix amabilis) is an ornamental eastern Asian conifer with a long evolutionary history. It is one of the few deciduous gymnosperms which sheds its leaves after an intensive golden autumnal coloring. Zusammenfassung Die Goldlärche (Pseudolarix amabilis) ist eine ostasiatische Konifere mit einer langen evolutionären Geschichte. Den volkstümlichen Namen kann man erst im Herbst verstehen, wenn sich die Nadeln vor dem Abwerfen in ihrer prächtig leuchtenden Herbstfärbung präsentieren.
Svensk Botanisk Tidskrift, 2015
Der Palmengarten, 2014
Die Sizilien-Tanne (Abies nebrodensis) ist mit lediglich nur noch ca. 30 Individuen am Naturstand... more Die Sizilien-Tanne (Abies nebrodensis) ist mit lediglich nur noch ca. 30 Individuen am Naturstandort eine der seltensten und am meisten bedrohten Koniferen-Arten der Welt. Im Forstarboretum Freiburg-Gunterstal, Deutschland, wurde eine Flache von 0,3 ha als Erhaltungskultur angelegt.
Trees-structure and Function, Jun 16, 2023
Key message We examined the leaf structure of two basal Cupressus species with a distinct leaf di... more Key message We examined the leaf structure of two basal Cupressus species with a distinct leaf dimorphism. Some foliar features are regarded as ancestral and it is suggested that drought adaptation was one of the important ecological drivers in the evolution of the Cupressus genus. Abstract Leaf morphology and anatomy of two Cupressus species, C. nootkatensis and C. vietnamensis, were investigated with classical paraffin technique and scanning electron microscopy (SEM). Like all Cupressus species these two are characterised by a dramatic change in the foliage. Juveniles have needle leaves first before they change abruptly to the mature scale leaf type. In C. vietnamensis, needle-leaved shoots occur next to scale-leaved ones even on mature trees, which is unique among today´s Cupressus species. Adults of C. nootkatensis develop only scale leaves throughout. In both taxa, the scale leaves show a distinct dimorphism between lateral and facial leaves, which are arranged in a flat spray; the foliate shoots are two-dimensionally flattened. These scale leaves show several xeromorphic features; e.g. strongly reduced leaf size, stomata with high, collar-like Florin rings, the presence of a distinct hypodermis as a continuous layer and well-developed transfusion tissue. The needle leaf type is found in Cunninghamia which is the basal member of the Cupressaceae and so is regarded as the ancestral condition and scale leaves as a derived one. Scale leaves are found in all the members of the cupressoid clade even within the basal taxa from mesic habitats. However scale leaves are a preadaptation to survival under xeric conditions and they are likely an evolutionary driver of the radiation of Cupressus into arid environments, as has also been the case in genera such a Callitris.
Der Palmengarten, Dec 30, 2014
Lychee (Litchi chinensis) and rambutan (Nephelium lappaceum) are evergreen tropical trees. Their ... more Lychee (Litchi chinensis) and rambutan (Nephelium lappaceum) are evergreen tropical trees. Their delicious fruits are edible. Morphology, biology and use of these species are outlined. Zusammenfassung Litchi (Litchi chinensis) und Rambutan (Nephelium lappaceum) sind immergrüne tropische Bäume. Ihre wohlschmeckenden Früchte sind essbar. Morphologie, Biologie und Verwendung werden vorgestellt.
Zweifelsohne gehört der Ginkgo auch in Mitteleuropa zu den bekanntesten fremdländischen Baumarten... more Zweifelsohne gehört der Ginkgo auch in Mitteleuropa zu den bekanntesten fremdländischen Baumarten und erst Recht zu den berühmtesten sog. "lebenden Fossilien". Wer kennt nicht seine ungewöhnlichen, an der Spitze meist zweigeteilten Blätter (Abb. 1), die regelmäßig in der Werbung für Medikamente gegen das Altern oder auch in Form von Broschen zu sehen sind? Besonders im Herbst zum Zeitpunkt der intensiven gelben Herbstfärbung als auch nach dem Blattabwurf, wenn die leuchtend silbrig-gelben Samen noch am Baum hängen, fallen die Bäume besonders auf (Abb. 2). Nachfolgend wird die Paläobotanik, Systematik und Morphologie dieser einzigartigen Gattung vorgestellt.
Zaubernuss-Arten (Hamamelis spp.) sind in Mitteleuropa häufig gepflanzte Ziergehölze und stellen ... more Zaubernuss-Arten (Hamamelis spp.) sind in Mitteleuropa häufig gepflanzte Ziergehölze und stellen wichtige Solitärsträucher in Garten-und Parkanlagen dar. Im Sommer sind sie eher unauffällig, im Herbst aber zeigen sie eine spektakuläre Herbstfärbung und im Winter (Ausnahme H. virginiana) bezaubern sie durch ihren sehr frühen Blütezeitpunkt (Abb. 1 & 2). Möglicherweise haben sie daher auch ihren deutschen Namen.
Trees-structure and Function, Jun 16, 2023
Key message We examined leaves of a suite of microphyllous woody plants and describe a little-kno... more Key message We examined leaves of a suite of microphyllous woody plants and describe a little-known form of leaf peltation for the first time and also investigate strongly reflexed leaves in two distantly related lineages. Abstract Plants cope with a range of environmental conditions, especially related to water relations, and have developed an array of physiological and structural solutions to maintain a functional water balance. There has been considerable recent work on physiological solutions to water deficit but little attention paid to leaf characteristics. In many species there is a change in leaf form from seedlings to adults. We examine such changes in several small-leaved species from the distantly related Asteraceae and Myrtaceae, some of which develop micropeltate or reflexed leaves as adults. All are native to dry or seasonally dry sites. Three major morphological groups were recognised as follows: (1) leaves erect, nonpeltate and scalelike (Ozothamnus hookeri), (2) leaves erect and peltate (Phaenocoma prolifera, Regelia inops), (3) Leaves reflexed (Olearia lepidophylla, Ozothamnus scutellifolius, Ozothamnus reflexifolius, Melaleuca diosmifolia). The microphyllous peltation in P. prolifera and R. inops in the absence of a meristematic fusion/bridge differs from typically peltate leaves. These smallleaved taxa occur in open, high light environments which are very different from the mesic, shaded understorey habitats of typical peltate-leaved plants. Many small-leaved species have leaves closely appressed to the stem and often with recurved margins. The erect leaves are functionally similar to reflexed leaves. Environmental filtering leads to superficially similar plant forms that may have somewhat different ontological origins. Such morphological forms are examples of convergent evolution in distantly related species but within each family are likely phylogenetically related.
Trees-structure and Function, Mar 26, 2018
Key message In Melaleuca minutifolia mature leaves are linear, in Melaleuca micromera scale-like ... more Key message In Melaleuca minutifolia mature leaves are linear, in Melaleuca micromera scale-like and peltate. This peltation is caused by swollen basal mesophyll without meristematic fusions. Thus, a novel peltation strategy is described. Abstract The foliar change of two Australian Melaleuca species (Myrtaceae) was investigated in different ontogenetic stages from cotyledons up to the mature leaf types. In both taxa (M. minutifolia and M. micromera), a strong leaf reduction occurs. While in M. minutifolia the mature leaf type is linear, inverse bifacial and strongly adpressed to the shoot axis, in M. micromera it is scale-like, aequifacial, minute and peltate. The mature leaf type of M. micromera is one of the rare examples of peltation among woody species. The ontogenetic studies on the mature peltate leaf type of M. micromera showed that a shield-like leaf base and typical peltate leaf morphology can be formed, not exclusively by meristematic fusions, as is the case for peltate leaves in the classical sense, but instead by strongly swollen mesophyll, particularly in the basal part of the leaf. While most species with peltate leaves are herbaceous perennials from very moist to aquatic habitats and lack reduced leaves, the four Melaleuca species known with the M. micromera type of peltation are from habitats showing either seasonal water stress, soil infertility or both and all show extreme leaf reduction. Given our morpho-anatomical data, it is clear that, as well as the classical type of peltation, a novel, second strategy for achieving peltation needs to be distinguished. The two types are correlated with quite different environmental conditions.