The presence of cellulose-containing cell walls has been proposed as a taxonomic character in the genus Ceratocystis Ellis and Halsted (Jewell, 1974; Upadhyay, 1981; De Hoog, 1974; De Hoog and Scheffer, 1984; Benny and Kimbrough, 1980; Harrington, 1981; von Arx, 1974). The significance of this trait derives from its scarcity among the fungi. Among the Eumycota sensu von Arx (1974), cellulose is known to occur only in certain species of Ceratocystis s.l (Bartnicki-Garcia, 1968; Barr, 1983; Upadhyay, 1981). With few exceptions, within Ceratocystis s.l, cellulosic cell walls occur in the same species that have holoblastic conidiogeny, cycloheximide tolerance, and cell walls with rhamnose (Harrington, 1981; Jewell, 1974; Spencer and Gorin, 1971; Upadhyay, 1981). De Hoog and Scheffer (1984) summarize the evidence supporting the disposition of these species in Ophiostoma H. & P. Sydow while retaining species with enteroblastic conidiogeny, sensitivity to cycloheximide and neither cellulose nor rhamnose in their cell walls, in Ceratocystis s.s. This suite of characters' biochemical, developmental/morphological, and metabolic-argue strongly for the segregation of these species into Ceratocystis s.s. and Ophiostoma as accepted by recent treatments (De Hoog, 1974; De Hoog and Scheffer, 1984; Benny and Kimbrough, 1980; von Arx, 1974), supported by Harrington (1981) and used herein.