Biology Reference
In-Depth Information
data on the nectariferous structures modes of secretion in these important
plant groups are required.
3.8.3
Early-branching monocots
The unplaced
Petrosaviaceae
(now considered basal in a clade that includes
most monocots, except Alismatales) possesses septal nectaries (Rudall,
2002; Remizowa et al., 2006).
Acorales.
This monotypic order is a sister group of the monocotyledons.
Nectaries are absent, although non-secretory septal slits are present (Rudall
& Furness, 1997; Buzgo & Endress, 2000), which are reminiscent of septal
nectaries. A droplet that lasts for 1-2 h is secreted at the tip of the stigma,
but it is unclear whether it contains sugar and functions as a pollinator attrac-
tant or whether it simply catches pollen (Buzgo & Endress, 2000).
Alismatales.
Septal nectaries (mostly infralocular; cf. Rudall, 2002) are fre-
quent in families from this order, e.g.,
Alismataceae
,
Aponogetonaceae
,
Butomaceae
,
Limnocharitaceae
, and
Toefieldiaceae
(Daumann, 1970; van
Heel, 1988; Smets et al., 2000; Remizowa et al., 2006), but absent in
Araceae
,
Cymodoceaceae
,
Hydrocharitaceae
,
Juncaginaceae
,
Posidoniaceae
,
Pota-
mogetonaceae
,
Ruppiaceae
,
Scheuchzeriaceae
, and
Zosteraceae
, most
of which have abiotic pollination mainly by water (Cronquist, 1981, 1988;
Vogel, 1998d). Other types of nectaries are found as well: in Alismataceae
staminal and carpellodial (Smets et al., 2000), in Araceae stigmatic (Vogel,
1983) and staminodial (Vogel, 1998d), and in Hydrocharitaceae staminodial
nectaries (Scribailo & Posluszny, 1985).
3.8.4
Monocots
Septal (or gynopleural after Smets & Cresens, 1988) nectaries are exclusive
to many monocotyledons (Brown, 1938; Daumann, 1970; Rao, 1975;
Schmid, 1985; van Heel, 1988; Smets et al., 2000; Rudall, 2002), resulting
from incomplete fusion of a small region of the carpel margins, which are
otherwise fused. In dicots, there are non-secretory septal slits in
Saruma
(Aristolochiaceae; Igersheim et al., 2001) and
Koelreuteria
(Sapindaceae;
Decraene et al., 2000a) and non-secretory septal cavities in
Cneorum
(Rutaceae; Caris et al., 2006). Septal nectaries have a variety of structural
possibilities, since the ovaries can be superior, semi-inferior, or inferior; the
nectaries may be infralocular or interlocular/supralocular (terminology of
Simpson, 1998), the slits can be located in different positions, and the inter-
nal structure can be simple or labyrinthine (Daumann, 1970; Schmid, 1985,
