Biology Reference
In-Depth Information
Cytisophyllum
,
Erinacea
,
Genista
,
Petteria
,
Retama
,
Spartium
,
Spartocyti-
sus
) do secrete nectar (Bisby, 1981; Vogel, 1997; Westerkamp, 1997;
Galloni & Cristofolini, 2003). Bisby (1981) described these nectaries as ex-
trastaminal, but Vogel (1997) showed through histological analyses that they
are non-structural nectaries located in the filament column. A special case
was reported in several species of
Stylosanthes
: as the nectary is destroyed
by the elongation of the receptacle into a long tube, an apparently non-
homologous nectar gland develops at the distal end of the tube (Vogel,
1997).
Polygalaceae
tends to have highly specialized zygomorphic flowers
with secondary pollen presentation (Brantjes, 1982). Members of this family
have an intrastaminal nectary surrounding the gynophore or the ovary, but in
derived taxa it may be unilateral as an adaxial gland (Cronquist, 1981;
Westerkamp & Weber, 1999). No data on nectaries in
Quillajaceae
are
available, but nectar has been observed in some species (Bugg, 1987).
Rosales.
Nectaries are absent in some wind-pollinated families:
Barbeya-
ceae
,
Cannabaceae
,
Moraceae
(except
Ficus
, which is insect-pollinated but
not nectariferous),
Ulmaceae
, and
Urticaceae
(Dickinson and Sweitzer,
1970; Cronquist, 1981; Judd et al., 2002). When present, nectaries are
mainly hypanthial or petal. In
Dirachmaceae
, nectaries are epidermal, as
glands associated with the petal bases; in addition, they are covered by
trichomes on a protuberance that protects the nectar (Link, 1994a; Decraene
& Miller, 2004).
Rhamnaceae
members show hypanthial nectaries that can
be attractive parts of the flower in an intrastaminal position: they can be
rings around the ovary (resembling receptacular nectaries, but hypanthial in
origin), can extend over the inner surface of the lower half of the floral tube,
or can be restricted to laminar projections of the hypanthium (Medan &
Aagesen, 1995). In some species, the nectary is separated from the
gynoecium by intercalary growth. The pubescence that is common in the
flower tube can be explained as a hairy barrier that separates the nectary
from the outer environment (Medan & Aagesen, 1995). The flowers of
Elaeagnaceae
also have well-developed hypanthial nectaries (Cronquist,
1981; Decraene & Miller, 2004), although some taxa are anemophilous
(
Hippophae
). In
Rosaceae
, the inner surface of the hypanthium is commonly
nectariferous (Cronquist, 1981; Smets, 1986; Judd et al., 2002; Buban et al.,
2003; Evans & Dickinson, 2005). In the literature, Rosaceae nectaries are
frequently considered receptacular (e.g., Radice & Galati, 2003; Weryszko-
Chmielewska et al., 2003), probably following Fahn's (1979) interpretation.
Cucurbitales.
Nectaries are lacking in
Coriariaceae
(Thompson & Gornall,
1995) and
Datiscaceae
(Philbrick & Rieseberg, 1994), which are wind-
pollinated, and also in
Begoniaceae
, which has pollen flowers, except for a
