Fruit structure and development of anemochorous Exbucklandioideae clade within the mainly ballistochorous Hamamelidaceae familyстатьяИсследовательская статья
Статья опубликована в журнале из списка Web of Science и/или Scopus
Аннотация:Hamamelidaceae (Saxifragales) are widely distributed throughout both hemispheres, well represented in the fossil records and are an important component of palaeo and modern ecosystems. However, the structure of their fruits has not yet been investigated in detail. In contrast to most Hamamelidaceae ballistochorous taxa, the representatives of Exbucklandioideae are anemochorous. In order to determine the functional and evolutionary significance of the fruit structure that secures these two fundamentally different dissemination strategies, using light microscopy we studied the fruits of four species belonging to both genera of Exbucklandioideae subfamily – Exbucklandia R.W.Br. and Rhodoleia Champ. ex Hook. We have revealed that the fruits of Exbucklandioideae are capsules of the Hamamelis type and are characterised by a continuous sclerenchymatous zone located in the inner zone of the mesocarp and the endocarp. Such a structure, as well as the differentiation of the mesocarp into parenchymatous peripheral and sclerenchymatous inner zones, is also observed in all other but the ballistochorous Hamamelidaceae taxa. These features confirm the monophyly of the Hamamelidaceae family and support the classification of the subfamily Exbucklandioideae within it. The stout sclerenchymatous zone of the pericarp secures a highly specialised adaptation to ballistochory in all other subfamilies, whereas in Exbucklandioideae, the same structure is only responsible for protecting the seeds during maturation and fruit dehiscence, rather than providing seed ejection with force. It has been shown that the anemochorous dissemination of Exbucklandia and Rhodoleia is the result of a transformation of the seeds into a flat, winged form that allows them to fly.
