Of 293 plants scored for disarticulating or intact rachis, 223 plants disarticulated and 70 plant remained intact, or had spikes that broke only at one point. These values approach a 3 : 1 ratio and are consistent with the interpretation that intact rachis is controlled by a single recessive gene. If we consider the range of types for spike disarticulation listed for longissima by EIG (1929), the control of intact rachis in longissima may be more complicated.

Spikes of some of the segregants from the F₂ population approached the morphology of sharonensis spikes, and F₃ seed of these plants will be grown in 1978. These results are consistent with the interpretation that Ae. sharonensis may have originated as a hybrid segregant.

I hope that taxonomists will not use these results to merge Ae. longissima into Ae. bicornis, as they ealier used chromosome pairing and fertility studies to merge sharonensis into longissima. All these three species have different morphologies and different ecological requirements (ANKORI and ZOHARY 1962).

Literature Cited

ANKORI, H. and D. ZOHARY 1962. Natural hybridization between Aegilops sharonensis and Ae. longissima. Cytologia 27 : 314-342.

EIG, A. 1929. Monographisch-kritische Uebersicht der Gattung Aegilops. Reprium nov. Spec. Regni Veg. 55 : 1-288.

KIMBER, G. 1961. Cytogenetics of haploidy in Gossypium and Triticum. Ph.D.thesis, Univ. Manchester, pp. 297.

ROY, R.P. 1959. Genome analysis of Aegilops sharonensis. Genetica 29 : 331-357.

TANAKA, M. 1955. Chromosome pairing in hybrids between Aegilops sharonensis and some species of Aegilops and Triticum. Wheat Inf. Serv., Kyoto Univ. 2 : 7-8.

WAINES, J.G. and B.L. JOHNSON 1972. Genetic differences between Aegilops longissima, Ae. sharonensis and Ae. bicornis. Can. J. Genet. Cytol. 14 : 411-416.

(Received Aug. 20, 1977)