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The eighteenth-century Malthusian prediction of population growth outstripping food production has not yet come to bear. Unprecedented agricultural land expansions since 1700, and technological innovations that began in the 1930s, have enabled more calorie production per capita than was ever available before in history. This remarkable success, however, has come at a great cost. Agriculture is a major cause of global environmental degradation. Malnutrition persists among large sections of the population, and a new epidemic of obesity is on the rise. We review both the successes and failures of the global food system, addressing ongoing debates on pathways to environmental health and food security. To deal with these challenges, a new coordinated research program blending modern breeding with agro-ecological methods is needed. We call on plant biologists to lead this effort and help steer humanity toward a safe operating space for agriculture.

Phylogenetic relationships among the 21 taxa comprising Helianthus sect. Helianthus and three outgroup species were assessed by restriction site mapping of the 18S‐25S nuclear ribosomal RNA gene family. Wagner parsimony analysis of the 41 restriction site or length mutations observed produced a single 59‐step most parsimonious tree. This tree was then compared to a cytoplasmic‐based plastid phylogeny for this group. Several major discrepancies were observed between the two phylogenies suggesting both recent and ancient introgression. Furthermore, three cases of diploid hybrid speciation are unambiguously documented and a fourth case is suggested. These data are interpreted to suggest that evolution in Heliathus is reticulate rather than exclusively dichotomous and branching.

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Perhaps no one has had a greater influence on the development of hybridization theory than Dr. Ledyard Stebbins. However, his contributions have not been restricted to his writings or lectures alone. Many of you have marveled at the great authority with which Dr. Stebbins identified the hybrid status, parentage, and ploidal level of plants in the field or on herbarium sheets. He didn't seem to need all the modern techniques that the current generation of botanists is both blessed and burdened with. For example, I remember a short field trip with Dr. Stebbins in the fall of 1984 to look at some sunflower hybrids near Davis. The plants were dead, only a few dried leaves, stalks, and floral heads remained, yet he confidently identified parental, hybrid, and backcrossed generations. Ironically, after 2 yr of careful molecular studies, I essentially confirmed his initial observations (Rieseberg, Soltis, and Palmer, 1988). Thus, I came to the conclusion that he was able to see things in plants that escaped less careful or less knowledgeable observers such as myself.