| Abstract: | The pollen morphology of 19 species and 2 varieties in the genus Ribes Linn. was
examined under light microscope (LM) and scanning electron microscope (SEM).
Pollen grains of the genus are subspheroidal, 15.0-41.67 μm in diameter, more or less
circular to obtusely quadrangular in outline with all sides slightly concave, or with alternating
concave sides, or elliptic under SEM, 5-, 6-zonocolporate or 5-, 6-pantoporate. Exine
usually thin, 1.0-1.5μm, without visible differentiation between nexine and sexine. Exine is
psilate or sometimes coarsely or finely granular or verrucate.
The most important characteristic of pollen in this genus is the presence of a “rugoid
Area” (ectoaperture) around the endoaperture under SEM. It is different from the other taxa
of Saxifragaceae (s. 1.). Based on the pollen morphology and the external morphological characteristics, the treatment of the genus Ribes as an independent family (i.e. Grossulariaceae)
by many taxonomists is reasonable.
The pollen grains of the genus can be divided into 4 types from the materials examined:
(1) Grossularia-type. ectoaperture colpate, with two endoapertures, exine psilate. (2) Ribes-type:
ectoaperture porous or colpate, with one or two endoapertures, exine mostly psilate. (3) Grossularioides-type: ectoaperture porous, circular, small, with one endoaperture, exine verrucate.
(4) Berisia-type: ectoaperture porous, subcircular to circular, large, with one endoaperture exine mostly psilate. The observation made by the present authors supports the subdivision of
Ribes into the subgenera Grossularia, Ribes, Grossularioides and Berisia by many taxonomists
based on the other morphological characteristics, and the observation by the present authors is
in accordance with this view. Pollen information also shows the close relationships among thefour subgenera and therefore they belong to the same genus — Ribes. |
