Sucrose
+
O
OH
OH
OH
OH
Glucose
Fructose
OH
O
OH
OH
OH
HO
HO
O
HO
OH
OH
OH
O
HO
OH
OH
OH
O
OH
OH
OH
HO
HO
O
O
O
HO
OH
HO
OH
OH
HO
HO
HO
Invertase
Mannose
Arabinose
Xylose
O
O
O
HO
OH
OH
HO
OH
HO
HO
OH
Maltose
O
O
O
HO
HO
OH
OH
HO
OH
OH
OH
Melibiose
O
O
O
O
O
OH
HO
HO
OH
HO
OH
OH
HO
OH
OH
OH
O
O
O
HO
O
O
HO
HO
OH
OH
HO
OH
HO
OH
OH
OH
A
B
C
Raffinose
Melezitose
D
Fig. 5 Sugars of floral nectar. (a) Main sugars of floral nectar. The monosaccharides glucose and fructose result from the breakdown of sucrose by
invertase. (b) Other monosaccharides occurring in floral nectar. (c) Disaccharides. (d) Oligosaccharides are rare (occur in some families, such as Myrtaceae and
Orchidaceae)
28 Diversity of Floral Glands and Their Secretions in Pollinator Attraction
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