Biology Reference
In-Depth Information
Figure 3.
Epidermal cell wall and cuticle of a secretory hair of the
Platanthera chlorantha
(Orchidaceae) floral nectary. Nectar presumably flows out through fibrillar outgrowths of the
outer cell wall (microchannels) present in the cuticle. (This picture was kindly provided by
Malgorzata Stpiczyńska, Department of Botany, Agricultural University in Lublin, Poland.)
Bar = 0.4 µm; cu = cuticle; cw = cell wall.
tubular interruptions of the cuticle in continuity with the cell wall; some of
them seem to have direct communication with the outside (Koteyeva, 2005).
Very similar microchannels are described in the cuticle of epidermal cells of
the
Echinacea purpurea
(Asteraceae) nectary, although they have no direct
communication with the outside (Wist & Davis, 2006).
Complex cuticle organization with a lamellar-type outer layer and a re-
ticulate-type inner one has been described in the floral nectary of
Aptenia
cordifolia
(Aizoaceae) and
Limodorum abortivum
(Orchidaceae) (Meyberg
& Kristen, 1981; Figueiredo & Pais, 1992).
2.1.1
Secretory trichomes
The nectary epidermis may have trichomes as the secretory structures. The
morphology of trichomes varies, and includes the following types:
•
Unicellular trichomes as in the floral nectaries of
Lonicera
(Caprifoliaceae)
(Fahn & Rachmilevitz, 1970)