The genus Cotoneaster has been thoroughly studied and documented in Belgium for more than 10 years now. In addition to one rather rare and local native species (Cotoneaster integerrimus Medik.) at least 24 additional, reliably identified non-native species are known to occur / to have occurred (see the updated Excel-version of the “Catalogue of neophytes in Belgium” on http://alienplantsbelgium.be/ for an overview). A few more require further study and confirmation. At least one collection for every species was checked and approved by Mrs. Jeanette Fryer (England), the leading expert on the genus.
A paper dealing with the current knowledge on Cotoneaster in Belgium is in preparation. Pending its completion and publication information will be made available here bit by bit. For each of the species treated in the manuscript species accounts will be presented, each copiously illustrated with original photographs and herbarium scans from Belgian plants.
Additional useful information on Cotoneaster in Central Europe is available here: http://offene-naturfuehrer.de/web/Cotoneaster_%E2%80%93_Zwergmispel_in_M....
For a reliable identification of Cotoneaster information is required at different stages of development during the season:
1) When in flower: petals patent or erect; petal colour; anther colour; number of flowers per inflorescence; leaf shape, -dimensions and -indumentum of non-flowering shoots;
2) When in fruit: colour and shape of the fruits; number of nutlets per fruit;
3) During winter: absence or presence of leaves by mid-January (deciduous vs. (semi-) evergreen species).
The fruits by far provide the most useful information but for most species information for all three stages of development will be essential. The number of flowers per inflorescence is best counted in May-June (the number of fruits per inflorescence is usually smaller since not all flowers mature and/or fruits may have been eaten by birds). Leaf shape, leaf indumentum and leaf dimensions should be assessed on summer leaves of non-flowering branches (those of flowering branches are often smaller and more hairy). The number of nutlets per berry often varies: it should be counted in at least 5-10 berries.
Theoretically, species of Cotoneaster can germinate where-ever they are dropped by berry-eating birds. However, there is an obvious tendency for particular habitats: they usually develop on dry, stony, gravelly or sandy substrate, in full sun or half-shade and completely lack in moist conditions. Favourable habitats are coastal dunes, under or on the verge of conifer plantations (especially Pinus, Picea), in young Betula woodland, on old walls, on calcareous slopes, abandoned railway yards, spontaneous woodland, on former chalk, gypsum or ash deposits, coal mining heaps, cemeteries, clearings in woodland, etc. Most species furthermore seem to prefer rather calcareous substrates although some also occur on more acidic soils. It is important to stress that most bird droppings fall within relatively short distance from the parent plant; as a consequence species of Cotoneaster are most often found in the vicinity of plantations. Records in more remote areas seem to be rather exceptional.
Cotoneaster is an important genus in terms of invasion ecology. An increasing number of species occurs in valuable habitats and may out-compete vulnerable, native species. A reliable identification is an essential tool in studies on plant invasions. Botanists who wish to collaborate with the inventory of Cotoneaster in Belgium may send photos or herbarium specimens (accompanied by a herbarium label and preferably with information on all three stages of development that are essential for an accurate identification; see above) to the author for determination or confirmation:
National Botanic Garden of Belgium
Domein van Bouchout