Morphological variability and resource allocation in the annual teosinte (<Emphasis Type="Italic">Zea mays</Emphasis> ssp.<Emphasis Type="Italic"> mexicana</Emphasis> (Schrader) Iltis) of the Toluca Valley,Mexico

This study explores the morphological variability and resource allocation of weedy, annual teosinte (Zea mays ssp. mexicana (Schrader) Iltis, Chalco race) from the Valley of Toluca, central Mexico, and compares it with data reported for maize. One hundred mature and fertile teosinte plants were selected for variation in size and measured. The extremes found for fertile plants were 0.12 and 3.5 m in height and 0.09 vs. 694 g in weight. Fruit were polymorphic, with significant correlation between color and weight. Small plants invested slightly more biomass in the leaves and tall plants invested more in the stem. The minimum mass necessary to produce fertile plants was much lower in teosinte than in maize. Very small teosinte plants formed only female inflorescences, whereas maize produces a tassel. The harvest index was similar to landrace maize, and did not decrease in taller plants, as teosinte can increase the reproductive sink. Toluca teosinte retains several important characteristics of weeds: size variability, adaptation of fruit quantity to environmental conditions, and fruit polymorphism.