Biology Reference
In-Depth Information
heterogeneous. He lists four kinds of nectarioles: glands, idioblasts, clusters
of mesenchymatic cells, as well as trichomes. Accordingly, there is some
overlap among nectarioles, trichomatous nectaries, and epithelial nectaries.
Considering the great variability of these few-celled epidermal structures, it
seems easier to refer to them plainly as epidermal nectaries, even though
they may contain a few subepidermal cells. Larger, conspicuous, more com-
plex, frequently vascularized secreting structures will be referred to as
nectaries of a floral whorl (e.g., receptacular, sepal, petal, or staminal nectar-
ies), and correspond to the mesenchymatous type of Vogel (1977).
Trichomes
are by far the most common epidermal nectaries. They may
be unicellular (e.g., Dipsacales; Wagenitz & Laing, 1984; Orchidaceae;
Stpiczyńska et al., 2005; Tropaeolaceae; Rachmilevits & Fahn, 1975), or multi-
cellular (Adoxaceae; Erbar, 1994; Wagenitz & Laing, 1984; Anacardiaceae;
Wunnachit et al., 1992, Malvaceae
s.l.
; Vogel, 2000; Leitao et al., 2005). Multi-
cellular trichomes can be either uni- or multiseriate, although both types are
usually present in the same plant group. Nectariferous trichomes may be
scantily dispersed (Sterculioideae; Vogel, 2000) or form compact, sharply
circumscribed cushions or carpets whose shapes may be taxonomically im-
portant in defining related plant groups (e.g., Bombacoideae, Malvoideae;
Vogel, 2000).
The following list includes the families (all dicots) known to have tri-
chomes, at least in some genera, where the trichomes are located on the
floral structure, as well as a reference:
•
Anacardiaceae: corolla (Wunnachit et al., 1992)
•
Aristolochiaceae: calyx (Daumann, 1959; Sakai, 2002)
•
Bignoniaceae: corolla tube (Lopes et al., 2002)
•
Capparaceae: receptacle (Schmid et al., 1984)
•
Convolvulaceae: sepal (Keeler & Kaul, 1984)
•
Cucurbitaceae: petal or hypanthium (Vogel, 1997)
•
Dipsacales: corolla tube (Fahn, 1979; Wagenitz & Laing, 1984; Smets,
1986; Erbar, 1994; Davis, 2003)
•
Lentibulariaceae: petal spur (Vogel, 1998a)
•
Malvaceae
s.l.
(Bombacoideae, Byttnerioideae, Dombeyoideae, Grewioi-
deae, Helicterioideae, Malvoideae, Sterculioideae, and Tilioideae): petal,
sepal, or androgynophore (Vogel, 2000; Leitao et al., 2005)
•
Myrsinaceae, Primulaceae, Theophrastaceae: generally corolla, rarely ovary
surface (Vogel, 1986, 1997)
•
Ranunculaceae: ovary surface (Peterson et al., 1979; Smets & Cresens,
1988)
