The interaction between pollinator size and the bristle staminode
of Penstemon digitalis (Scrophulariaceae).
However, the reproductive organs (stamen and pistil) are isolated in the flower by two morphological barriers: the staminode
crown, which isolates the stigmatic arms, and the petals (cogule) involving the anthers.
Commonly the odd stamen is more or less reduced to a staminode
or even lacking.
Pollination by deceit in Paphiopedilum barbigerum (Orchidaceae): a staminode
exploits the innate colour preferences of hoverflies (Syrphidae).
Trees; leaves digitate; staminode
undeveloped, 8-10 mm.
Androecium of 4 stamens, didynamous, filaments 30-32 mm long, adnate to the corolla tube for 15-17 mm, white, glabrous, coiling after anthesis; staminode
absent; anthers sagittate, 5-6 x 2-3 mm, coherent by the lateral walls, dehiscence by basal pores that develop into longitudinal slits.
Torchio (1974) described how females of a pollen-wasp butt the staminode
to reach the nectaries, thereby rasping their punctate thoracic dorsa against the dentate anthers.
In Heliconia, a single stamen develops as an infertile, often callose, staminode
(Kirchoff et al.
5 mm in diameter, smooth, lepidote; placentation central, ovules white, narrowly cylindrical, 10-11 per locule, filament of staminode
narrowly triangular, 3.
For identification and description of the different species we used the morphological characters of growth habit, leaf-size, flower-size, petal-size, nectar scale and staminode
size and shape, and also the density of setae and trichomes (scabrid and glochidiate).
For Watson and Dallwitz (1992-), a staminode
is a sterile stamen, or a modified structure identifiable as such, borne in the androecial region of the flower.
The adaxial and abaxial stamen pairs show various degrees of asymmetry; either pair can be missing entirely or develop only as staminodes
, or there may be a fifth stamen or staminode
present in the adaxial median position.