A heterodiaspore species features more than one diaspore type.
With HETERODIASPORY we describe the phenomenon that a species may produce diaspores of more than one type. Such species are marked with '1' in the column DIA_HETERO and more details are given in the textual comments for the species.
The differences in diaspore type within one species can be attributed to different levels:
- Species may produce different fruit types, fruits or even specialized vegetative parts that develop in various ways that affect the diaspore type. For instance, in some Rosa species the complete rose hip as well as a single nutlet may act as the diaspore if the rose hip opens - rarely - during maturity (Fig. 1). The rose hip diaspore is classified as a fleshy diaspore whereas the nutlets are classified as fruit segments that are released from a dehiscent fruit. This type of heterodiaspory can also be found in many pepo-species where the pepo as well as single seeds may act as diaspores.
Fig. 1. Rosa sp. - Both complete rose hip (left) and single nutlets (middle) after lateral rupture of the rose hip (right) can act as diaspores.
- Species may produce morphological different fruits (heterocarpy, seed heteromorphism). For instance, the central achenes of Calendula officinalis differ considerably from the achenes produced in the outer part of the fruit head (Fig. 2).
Fig. 2. Calendula officinalis - heteromorphic fruits (diaspores): from the inner part of the fruit head (left) and from the outer part of the fruit head with smooth and coarse surface (right).
- Species may produce diaspores that can break into smaller units which may also act as diaspores. For instance, in many Poaceae a complete spikelet as well as single florets may act as diaspores (Fig. 3).
Fig. 3. Festuca filiformis - The spikelet (left, without the basal glumes), a part of the spikelet (middle) or a single floret (right) can act as a diaspore.
Furthermore, some species produce not only generative diaspores but also vegetative parts which can enhance dispersal. Generally, we disregard unspecialized vegetative forms of dispersal like rhizoms etc. because they do not influence long-distance dispersal. In contrast, vegetative parts which allow long-distance dispersal, like turions or bulbils in the infructescence, are marked as 'specialized vegetative part' (see Diaspore Typology).
HETERODIASPORY was categorized by visual inspection of fruits and diaspores or respective images in addition to an intensive literature and web research.
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