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abundance of starch in the nectary parenchyma may vary as well (see Pacini
et al., 2003), but its systematic value is uncertain until more data are gath-
ered.
Vascular system. The type of vascular bundle which supplies the nectarifer-
ous parenchyma may, more commonly, consist of phloem only, or of both
phloem and xylem (e.g., Fahn, 1979, 2000; Mani & Saravanan, 1999;
Galetto & Bernardello, 2004; Vassilyev & Koteyeva, 2004b; Leitao et al.,
2005; Wist & Davis, 2006). On the other hand, no special bundles may irri-
gate the nectaries, these being supplied by the vasculature of the organs
located near them (e.g., Fahn, 1979, 1988, 2000; Said, 1982; Galetto, 1995b;
Ma et al., 2002). It should be mentioned that within a family the type of flo-
ral vasculature may differ among genera and species (e.g., Frei, 1955;
Kartashova, 1965; Fahn, 1979). Its systematic importance is therefore rela-
tive, although trends might be defined. At the same time, a correlation
between the type of vascularization and the level of nectar concentration and
type of sugars present in the nectar does not always exist (e.g., Kartashova,
1965; Fahn, 1979; Dafni et al., 1988).
Unfortunately, the majority of the available articles that deal with nectar-
ies frequently do not report information on these basic anatomical and
cytological aspects. Furthermore, most studies have been done in either sin-
gle species or in a reduced number of related taxa; it is therefore hard to fully
appreciate the systematic value of many of these traits. Further data on these
aspects for large numbers of taxa, as well as on patterns of infraspecific vari-
ability, are required.
3.1.3
Fate
The fate of the organs where the secretory tissue is located may be an indica-
tion of the nectary fate. This fact was taken into account by Smets (1986,
1988) who broadly divided nectaries into persistent (associated with non-
falling floral parts) and caducous (associated with falling floral parts). This,
however, does not mean that persistent nectaries will always continue to se-
crete nectar for long periods after anthesis, or during fruit development. Such
long-standing secretion occurs exclusively in post-floral nectaries (or post-
floral secretion, as preferred by Schmid, 1988).
The function of post-floral nectaries was interpreted as promotion of seed
dispersal (Faegri & van der Pijl, 1979) or attraction of insects, mainly ants,
for defence against herbivores, thus preventing fruit predation (e.g., Keeler,
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