ACHENE STRUCTURE AND TAXONOMY OF NORTH-AMERICAN BOLBOSCHOENUS (CYPERACEAE)

Surface and transverse section achene structures of Bolboschoenus mari timus, B. robustus, B. fluviatilis, B. novae-angliae, B. glaucus, and the putative hybrids B. maritimus x B. robustus and B. glaucus x B. ma ritimus from North America are described and illustrated with SEM micr ographs, The same three types of pericarp structure reported by Browni ng and Gordon-Gray (1993) from southern Africa were found except that the ''type 2'' (B. glaucus) was not matched precisely. Intermediate ac hene structures and other evidence support both the hybrid origin of B . novae-angliae (= B. fluviatilis x B. robustus) and hybridization bet ween B. glaucus and B. maritimus. The new combination Bolboschoenus no vae-angliae is made.