Yellow monkey flower (Mimulus guttatus) was used by
(Washington State University) as an example of the syncolpate pollen type, when I
took his palynology class back in the late Holocene. Its bizarre syncolpate form
is unique, so far as I know, to this member of the genus.
Monkey flower is a large (2 - 8 dm) riparian herb with horizontal stolons, occurring
from oceanside to mid-elevation (2200 m) in western North America, particularly the
Pacific Northwest. The 5-parted bilabiate flowers are showy (2-5 cm), yellow and
sometimes tinged with red; and the simple, opposite leaves are toothed.
Pollen light micrograph:
About 30 µm, spheroidal, psilate (scabrate [SEM]), with short but visible
columella (and perforations [SEM]) forming the "roughened" sculpturing pattern.
The bizarre aperture is "spiroaperature" (Erdtman, 1952, of course)
and may consist of separate furrows at one pole, an elliptical aperature, or an encircling
aperture at the pole of the grain.
The aperture is thin in light microscopy. Erdtman (1952) states that
M. cupreus and M. luteus have "spiroaperatures", however,
the UofAz collection of M. luteus contains 5-, 4-, and 3-colpate grains
in addition to grains with "spiroaperatures", which are not joined to form
a single encircling aperture as are those of M. guttatus.
The other collections of Mimulus at the UofAz have sculpture similar to
M. guttatus, but all are staphanocolpate except for M. cardinalis (a desert plant),
which is tricolporate, reticulate (shown right)!
Pollen scanning electron micrograph (SEM)
Note scabrae and perforations.
Production and Dispersal:
Pollinated by bumblebees (Kiang, 1972) so pollen production is low,
but the grains are occasionally rocovered from in aquatic sediments
due to the plant's riparian habitat preference.