Eleocharis compressa × Eleocharis erythropoda, a new natural hybrid spike rush from Ontario

Abstract

Partially sterile plants from eastern Ontario are identified as Eleocharis compressa × Eleocharis erythropoda on the basis of intermediacy in perianth bristle length, tubercle shape, achene surface roughness, length of rhizome internodes, culm cross-section shape, and length of terminal lobes of scales. Both putative parents occurred with the hybrid plants. The hybrid plants had tardily deciduous scales and either bifid or trifid styles. They superficially resemble E. erythropoda most closely but differ markedly in their scaly rhizomes with shorter internodes 3.8 – 7 mm long. They are most readily distinguished from E. compressa by their elliptic or broadly rectangular culm cross sections and some perianth bristles exceeding 0.5 mm in length. This putative hybrid involves taxa in different subseries that would normally be regarded as too distantly related to permit hybridization. Key words: Eleocharis compressa, Eleocharis erythropoda, Cyperaceae, hybrid, taxonomy, classification.