Biology Reference
In-Depth Information
Humiriaceae
the nectaries are intrastaminal and free from the filaments (Link,
1992a). For
Irvingiaceae
, large intrastaminal receptacular annular nectaries
are reported, which are unusual for having 10-15 strictly localized stomata
that are deeply sunken in the nectariferous tissue (Link, 1992b). In
Ixonan-
thaceae
, both prominent intrastaminal annular as well as staminal nectaries
(on the filament bases) are known (Link, 1992d). In
Euphorbiaceae
, an extra-
staminal or intrastaminal receptacular nectary, either continuous or five-
segmented, is present (Cronquist, 1981; Webster, 1994; Freitas et al., 2001), or
the typical nectary glands of the bracts of
Euphorbia
and related genera
(Hoppe, 1985; Papp, 2004). (See “Euphorbiaceae” on page 49 for a detailed
description of the nectary types.) In
Linaceae
, nectaries are staminal, located
dorsally at the bases of the filaments or at the inner base of the petals (Brown,
1938; Cronquist, 1981).
Passifloraceae
bears clearly extrastaminal receptacu-
lar nectaries (Fahn, 1979; Cronquist, 1981; Bernhard, 1999b), which are not of
staminodial origin as previously suggested by Cronquist (Bernhard, 1999b).
The nectariferous tissue may also form a continuous ring or several separate
glands, as occurs in the former Turneraceae with five glands deeply immersed
in the receptacle (Gonzalez, 2001). Variations of systematic importance
among species and genera have been found (Bernhard, 1999b; Gonzalez,
2001). In
Phyllanthaceae
, receptacular nectaries, either intrastaminal or ex-
trastaminal, are found as well, although they may be absent in some genera
(Webster, 1994). In the mangrove family
Rhizophoraceae
, nectaries are re-
ceptacular, intrastaminal, and perigynous (Juncosa & Tomlinson, 1987). In
Salicaceae
(including most Flacourtiaceae), some taxa present reduced flow-
ers, lack nectaries, and are wind-pollinated (e.g.,
Populus
,
Xylosma
; Cronquist,
1981; Bullock, 1994). These plants show either (i) a continuous annular recep-
tacular nectary, (ii) separate nectar glands (often extrastaminal), or (iii)
interstaminal nectar lobes (Cronquist, 1981; Machado & Oliveira, 2000).
Some members have mixed wind and insect pollination (e.g.,
Salix,
with nec-
taries formed by one or two small glands, sometimes unequal, considered
calycinal in origin; Brown, 1938; Cronquist, 1981; Smets, 1986). In
Violaceae
, the anterior petal is spurred and nectar is secreted from a pair of
basal staminal appendages, specifically from the connective of the inferior
stamens, which project the nectar into the spur (Smets, 1986; Vogel, 1998b;
Freitas & Sazima, 2003). Occasionally, the glands are stalked and grow into
the hollow of the spur, some even reaching the bottom of the spur (Vogel,
1998b); the variation in these glands is systematically useful. On the other
hand, there may be striking inter- and intrapopulational variability in the spur
and nectaries in some
Viola
species (e.g., Herrera, 1988).
Oxalidales.
Receptacular nectaries are present in most families, but notably
absent in some
Elaeocarpaceae
, with specialized pollen flowers (Matthews
