School of Life Sciences | Ask A Biologist

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Sticking to His Subject

By Gail Maiorana

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  • Botanist: a person who studies plants. Botany... more
  • Chromosome: a long, thread-like molecule made of the chemical called DNA (deoxyribonucleic acid) that is held together with special proteins and is visible (with strong microscopes) during cell division... more
  • Grazing: land used for feeding cattle.
  • Nurseries: where plants are grown.
  • Specimen: sample.

pinkavaSometimes the police visit Professor Donald Pinkava. But they're not looking for him. They just have plant fragments that they found in cars or homes where a crime was committed. They need to identify the plant. So they come to Pinkava, who is director of the Arizona State University Herbarium.

The herbarium has 210,000 plants from all over the world. The plants have been dried and preserved and put in order of plant families. The police can ask Pinkava to go through the rows and rows of 7-foot-tall metal cabinets that contain plant specimens and compare those to what they found at the crime scene. Plant researchers from Arizona and all over the world have stopped by to study specimens.

hybrid 1Pinkava is a botanist who specializes in the study of cacti. Growing up in Ohio, he didn't have much experience with the spiny plant. But after he started teaching at ASU in 1964, his students kept bringing him samples of cacti and eventually he began his research on those plants.

His area of research is natural hybridization, that is, when two species of plants produce a new type that combines characteristics of both parents. He studies the chromosomes and pollen of cacti. The hybrids, or new plants, seem to be weaker than either of the parent plants, but nurseries sell some of the hybrids that look attractive.

hybrid 2His research involves going into the desert in the southwestern United States or northern Mexico. He must get permits from either the U.S. or Mexican governments to take plants back to his laboratory at ASU.

Grazing, pollution and wildfires have all changed the way cacti grow. Pinkava serves on a state board that recommends changes in laws that affect plants.

For further reading, Dr. Pinkava recommends Lyman Benson's The Cacti of the United States and Canada (1982, Stanford University Press)

Article by Gail Maiorana | Photos Courtesy of Dr. Pinkava

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Be part of Ask A Biologist

by volunteering, or simply sending us feedback on the site. Scientists, teachers, writers, illustrators, and translators are all important to the program. If you are interested in helping with the website we have a Volunteer page to get the process started.