Biology Reference
In-Depth Information
size is a complex process, involving not only the well-accepted interactions
with pollinators, but also interactions with herbivores, nectar robbers, seed
predators, and seed dispersers that may influence different reproductive traits
in plants (e.g., Armbruster, 1997; Galen, 1999; Aizen, 2003; Irwin et al.,
2004).
3.3
Basic types of floral nectaries
There have been numerous attempts to classify nectaries from different per-
spectives. No single classification system can take into account the remar-
kable diversity of locations, shapes, histology, and functions of nectaries.
Different classification systems may therefore have to be applied depending
on the purpose of our research; the classification used must be specified so
that readers understand our point of view. The simpler the classification sys-
tem, the better—most likely the tremendous variety of nectaries could be
fitted into an uncomplicated system with less difficulty.
The essential topographical nectary distinction was first proposed by
Caspary (1848): floral (on the flowers) and extrafloral (on vegetative or-
gans). But in recent times, as first recommended by Elias and Gelband
(1975), these terms have been extensively used as Delpino's (1868-1875)
functional classification into nuptial (related to the pollination process) and
extranuptial (not related to pollination) nectaries, respectively. This situa-
tion creates a terminological inconsistency because some “extrafloral”
nectaries are located in the “flower”, e.g., nectaries located abaxially on se-
pals and petals. To avoid this problem, the more recent classification
proposed by Schmid (1988) favours the use of reproductive (on any repro-
ductive structure from inflorescences, bracts, pedicels, to flowers and fruits)
and extrareproductive (on strictly vegetative organs) nectaries. Despite this,
the traditional use of the terms floral and extrafloral nectaries as suggested
by Elias and Gelband (1975) is still standard in botanical papers published
all over the world.
There are a few general nectary classifications that are helpful for floral
(and extrafloral) nectaries:
Zimmermann (1932) distinguished between (a) structural and (b) non-
structural nectaries, based on the basic structure of the nectaries and the
possibility of recognizing them macroscopically and/or microscopically, as
previously mentioned (sharply localized, histologically differentiated areas
where nectar is regularly exuded, and non-differentiated areas that sporadi-
cally are able to secrete nectar, respectively).
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