Biology Reference
In-Depth Information
Figure 6.
Receptacular (extrastaminal and intrastaminal) and hypanthial nectaries in a hypo-
thetical flower.
and this position may be of systematic interest to delimit species groups. On
the other hand, it has to be taken into account that occasionally, nectaries
may extend all the way from the corolla to the gynoecium and in these cases
(e.g., in some Celastrales; Matthews & Endress, 2005b), the distinction be-
tween intrastaminal and extrastaminal is of no use, as is its systematic
relevance.
3.4
Nectariferous spurs
Some angiosperm families have nectar spurs (Cronquist, 1981; Judd et al.,
2002), i.e., hollow, slender, saclike perianth outgrowths that secrete nectar.
These floral structures are thought to have had a strong influence in shaping
the evolution of plant and pollinator diversity (Hodges & Arnold, 1994), al-
though sometimes speciation in spurred taxa may be related to other features
(von Hagen & Kadereit, 2003). Several investigations have showed that nec-
tar spur morphology often correlates to the mouthparts and foraging habits of
pollinators (Nilsson, 1988; Temeles et al., 2002). In addition, there is evidence
