Although it is generally accepted that the tribe Genisteae has rather homog
eneous pollen, we have found considerable variation in pollen size and morp
hology in Cytisus and related genera (Argyrocytisus and Chamaecytisus), whi
ch match taxonomic groups defined on morphological grounds. The results of
Principal Component Analysis of pollen characteristics show the following:
Cytisus Sect. Alburnoides is well-delimited, with the smallest pollen grain
s and the simplest pattern in the lectum, fossulate-perforate to perforate;
No separation of C. villosus (Sect. Cytisus) from Sect. Alburnoides is obs
erved; Cytisus Sect. Spartopsis, with the largest pollen grains and reticul
ate to reticulate-fossulate ornamentation, forms an isolated group; C. font
anesii (Sect. Heterocytisus) stands apart from other Cytisus species by its
homogeneous ornamentation and the perforate instead of psilate-punctate ma
rgo. Thus, the pollen data supports its transfer to the separated genus Chr
onanthos; Pollen ornamentation and morphology also support the separation o
f Argyrocytisus battandieri and Chamaecytisus mollis from Cytisus.