Palynological research on Xyridaceae is hindered by limited suitable samples, especially in fluid preserved collections, due to the remote locations of most populations and the brief floral phenology (Carlquist, 1960; Campbell, 2004b).
Pollen from species representing all Xyridaceae genera were examined (Table 1) from samples obtained from dehisced herbarium specimen anthers or from liquid preserved specimens housed at the New York Botanical Garden (fixed in FPA and later transferred to 70% ethanol; Johansen, 1940).
Two main patterns of pollen morphology are present in Xyridaceae: spheroidal grains without an evident aperture, and pollen walls ornamented with projections, and elliptical, sulcate grains with fine wall ornamentation.
Clypeate pollen occurs in several unrelated Angiosperm families (Halbritter & Hesse, 1995), and in Xyridaceae is thus far known only in Achlyphila.
Observations of pollen morphology using scanning electron microscopy further distinguish the genera of Xyridaceae. Within the genera possessing apparently inaperturate pollen, the utility of pollen characters in circumscribing lower taxonomic groups is hampered due to limited samples that are difficult to comparatively assess due to harmomegathic effects.
Table 3 Palynological references for Xyridaceae (a) Taxon Reference Abolboda acaulis Maguire Carlquist, 1960 Abolboda bella Maguire Carlquist, 1960 Abolboda ebracteata Maguire & Wurdack var.
Anatomy and systematics of Xyridaceae with special reference to Aratitiyopea.
Contributions towards a monograph of Xyridaceae: A revised nomenclature for Abolboda (Xyridaceae).
The Xyridaceae pages an electronic monograph, http://sweetgum.nybg.org/ xyridaceae/The New York Botanical Garden, Bronx, New York.
Inflorescence architecture and floral morphology of Aratitiyopea lopezii (Xyridaceae).
Anatomy of Guayana Xyridaceae: Abolboda, Orectanthe, and Achlyphila.