NOTEWORTHY GRASSES FROM MEXICO IX. Alan A. Beetle APDO POSTAL 284 Hermosillo, Sonora, Mexico These are results from continuing studies sponsored by the Comision Tecnico Consultiva para la Determinacion Regional de los Coeficientes de Agostadero, fundada en 1966, y es depend-encia de la Secretaria de Agricultura y Recursos Hidraulicos. For previous papers see Phytologia 27:1974; 28:1974; 30: 1975; 35:1977; 38:1978; 47:1981, and 48:1981. Agropyron vaillantianum (Wulf. & Schreb.)Trautv. The Agropyron caninum -A. trachycaulum complex is mostly cespitose. The A. repens -A, smithii complex is generally rhizomatous. There is also a group of weakly rhizomatous plants with intermediate spike and floret characteristics which is undoubtedly of hybrid origin and which has caused a great deal of taxonomic difficulty and uncertainty. Plants from the central highland of Mexico have been rep-orted consistently since Urbina (cf, Urbina, 1897, Cat. de Plantas Mexicanus. Museo Nacional. Gramineae 376 -415.) as A, repens but nevertheless appear to represent the above mentioned intermediates which have been reported from Europe, Canada, the U.S.A. and Argentina. The Mexican distribution includes Chihuahua, Durango, Oaxaca (Beetle M -4761), Puebla, Mexico (Reeder & Reeder 3059), Tlaxcala, and Hidalgo (Rzedowski 21399 and 22435). The Mexican plants which have slender rhizomes, narrow leaves and large glumes are apparently native, and have a close superficial resemblance to A. pseudorepens . Pohl (1962. Agropyron hybrids and the status of Agropyron pseudorepens . Rhodora 64:143 -147) has shown that "the type of A. pseudo-repens is therefore a probable male-sterile hybrid of A. trachycaulum and A, smithii . Both species are known from Nebraska. The name A. pseudorepens , if used, should be applied only to such hybrids." The Mexican plants are compl-etely fertile producing both pollen and mature caryopses. 33
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