1/3 of cactus population facing extinction

In this Nov. 4, 2015 photo, Dr. Salvador Arias talks about endangered Biznaga cacti, inside the botanical gardens of the National Autonomous University of Mexico in Mexico City. About a third of the world's cactus species are threatened with extinction, the International Union for Conservation of Nature warns in a new report. (AP Photo/Rebecca Blackwell)

In this Nov. 4, 2015 photo, grafitti marks a cacus growing inside the botanical gardens of the National Autonomous University of Mexico in Mexico City. About a third of the world's cactus species are threatened with extinction, the International Union for Conservation of Nature warns in a new report. (AP Photo/Rebecca Blackwell)

In this Nov. 4, 2015 photo, an endangered echinocactus grusonii cactus, also known as Biznaga, grows inside the botanical gardens of the National Autonomous University of Mexico in Mexico City. About a third of the world's cactus species are threatened with extinction, the International Union for Conservation of Nature warns in a new report. (AP Photo/Rebecca Blackwell)

In this Nov. 4, 2015 photo, a visitor walks past varieties of cacti growing inside the botanical gardens of the National Autonomous University of Mexico in Mexico City. About a third of the world's cactus species are threatened with extinction, the International Union for Conservation of Nature warns in a new report.(AP Photo/Rebecca Blackwell)

In this Nov. 4, 2015 photo, an endangered echinocactus grusonii cacti, also known as Biznaga, is seen growing inside the botanical gardens of the National Autonomous University of Mexico in Mexico City. About a third of the world's cactus species are threatened with extinction, the International Union for Conservation of Nature warns in a new report.(AP Photo/Rebecca Blackwell)

In this Nov. 4, 2015 photo, endangered echinocactus grusonii cacti, also known as Biznaga, are seen growing inside the botanical gardens of the National Autonomous University of Mexico in Mexico City. About a third of the world's cactus species are threatened with extinction, the International Union for Conservation of Nature warns in a new report.(AP Photo/Rebecca Blackwell)

In this Nov. 4, 2015 photo, an endangered echinocactus grusonii cacti, also known as Biznaga, is seen inside the botanical gardens of the National Autonomous University of Mexico in Mexico City. About a third of the world's cactus species are threatened with extinction, the International Union for Conservation of Nature warns in a new report. (AP Photo/Rebecca Blackwell)

In this Nov. 4, 2015 photo, cacti grow inside the botanical gardens of the National Autonomous University of Mexico in Mexico City. About a third of the world's cactus species are threatened with extinction, the International Union for Conservation of Nature warns in a new report.(AP Photo/Rebecca Blackwell)

In this Nov. 4, 2015 photo, Dr. Salvador Arias is seen past a cluster of endangered echinocactus grusonii cacti, also known as Biznaga, as he looks at other species inside the botanical gardens of the National Autonomous University of Mexico in Mexico City. About a third of the world's cactus species are threatened with extinction, the International Union for Conservation of Nature warns in a new report. (AP Photo/Rebecca Blackwell)

In this Nov. 4, 2015 photo, a school group walks past varieties of cacti, as they tour the botanical gardens of the National Autonomous University of Mexico in Mexico City. About a third of the world's cactus species are threatened with extinction, the International Union for Conservation of Nature warns in a new report.(AP Photo/Rebecca Blackwell)

In this Nov. 4, 2015 photo, a cactus grows inside the botanical gardens of the National Autonomous University of Mexico in Mexico City. About a third of the world's cactus species are threatened with extinction, the International Union for Conservation of Nature warns in a new report.(AP Photo/Rebecca Blackwell)