In 2021, CPC contracted the Desert Botanical Garden to recollect seed from a population currently held in long term orthodox seed storage as part of an IMLS-funded seed longevity experiment. The National Laboratory for Genetic Resources Preservation will evaluate how germination tested viability and RNA Integrity of seed lots decline over time in storage.

There are currently more than 160 E. horizonthalonius nicholii specimens and over 700 seeds in the Desert Botanic Garden collection. The plants were salvaged from two sites and were collected in 1991 and 1993 from the Waterman Mountains. Almost 500 seeds were produced in cultivation, and additional seeds have been collected, but not accessioned, because they were from open-pollinated plants. Collected plants were initially heeled in a temporary sand bed until suitable planting sites were found. Many of the plants were potted into a sandy native soil and placed in the propagation area of the Garden. Seeds were processed and stored according to CPC guidelines. The plants would be used to produce seeds in a carefully controlled pollination attempt, to avoid any contamination with pollen from other taxa. One such attempt, accomplished by enclosing a group of flowering plants with a fine nylon netting, produced 462 seeds. Additional attempts will be made in an effort to build a seedbank of the species sufficiently large to use for reintroduction, if necessary. (Desert Botanical Garden 2000)

There are currently more than 160 E. horizonthalonius nicholii specimens and over 700 seeds in the Desert Botanic Garden collection. The plants were salvaged from two sites and were collected in 1991 and 1993 from the Waterman Mountains. Almost 500 seeds were produced in cultivation, and additional seeds have been collected, but not accessioned, because they were from open-pollinated plants. Collected plants were initially heeled in a temporary sand bed until suitable planting sites were found. Many of the plants were potted into a sandy native soil and placed in the propagation area of the Garden. Seeds were processed and stored according to CPC guidelines. The plants would be used to produce seeds in a carefully controlled pollination attempt, to avoid any contamination with pollen from other taxa. One such attempt, accomplished by enclosing a group of flowering plants with a fine nylon netting, produced 462 seeds. Additional attempts will be made in an effort to build a seedbank of the species sufficiently large to use for reintroduction, if necessary. (Desert Botanical Garden 2000)

There are currently more than 160 E. horizonthalonius nicholii specimens and over 700 seeds in the Desert Botanic Garden collection. The plants were salvaged from two sites and were collected in 1991 and 1993 from the Waterman Mountains. Almost 500 seeds were produced in cultivation, and additional seeds have been collected, but not accessioned, because they were from open-pollinated plants. Collected plants were initially heeled in a temporary sand bed until suitable planting sites were found. Many of the plants were potted into a sandy native soil and placed in the propagation area of the Garden. Seeds were processed and stored according to CPC guidelines. The plants would be used to produce seeds in a carefully controlled pollination attempt, to avoid any contamination with pollen from other taxa. One such attempt, accomplished by enclosing a group of flowering plants with a fine nylon netting, produced 462 seeds. Additional attempts will be made in an effort to build a seedbank of the species sufficiently large to use for reintroduction, if necessary. (Desert Botanical Garden 2000)

There are currently more than 160 E. horizonthalonius nicholii specimens and over 700 seeds in the Desert Botanic Garden collection. The plants were salvaged from two sites and were collected in 1991 and 1993 from the Waterman Mountains. Almost 500 seeds were produced in cultivation, and additional seeds have been collected, but not accessioned, because they were from open-pollinated plants. Collected plants were initially heeled in a temporary sand bed until suitable planting sites were found. Many of the plants were potted into a sandy native soil and placed in the propagation area of the Garden. Seeds were processed and stored according to CPC guidelines. The plants would be used to produce seeds in a carefully controlled pollination attempt, to avoid any contamination with pollen from other taxa. One such attempt, accomplished by enclosing a group of flowering plants with a fine nylon netting, produced 462 seeds. Additional attempts will be made in an effort to build a seedbank of the species sufficiently large to use for reintroduction, if necessary. (Desert Botanical Garden 2000) Threats

This extremely slow-growing cactus (which takes about 10 years to reach a height of 5 cm) is known from a particular micro-habitat type in 2 adjacent counties in Arizona, and immediately adjacent Sonora, Mexico. Collecting by hobbyists is a major threat, as are loss of habitat to urbanization, off-road vehicles, and copper mining.

In 1979, when E. horizonthalonius nicholii was first listed as endangered, threats included copper mining, urban development, off-road vehicle use and over-collection (Phillips et al. 1979, USFWS 1980). No evidence of grazing could be found on the BLM-ad

There are two primary populations, located in southwestern Pinal and north-central Pima counties (USFWS 1980, 1985, 1986). Land ownership is Tohono O'odam nation, BLM, and privately owned.

There are currently more than 160 E. horizonthalonius nicholii specimens and over 700 seeds in the Desert Botanic Garden collection. The plants were salvaged from two sites and were collected in 1991 and 1993 from the Waterman Mountains. Almost 500 seeds were produced in cultivation, and additional seeds have been collected, but not accessioned, because they were from open-pollinated plants. Collected plants were initially heeled in a temporary sand bed until suitable planting sites were found. Many of the plants were potted into a sandy native soil and placed in the propagation area of the Garden. Seeds were processed and stored according to CPC guidelines. The plants would be used to produce seeds in a carefully controlled pollination attempt, to avoid any contamination with pollen from other taxa. One such attempt, accomplished by enclosing a group of flowering plants with a fine nylon netting, produced 462 seeds. Additional attempts will be made in an effort to build a seedbank of the species sufficiently large to use for reintroduction, if necessary. (Desert Botanical Garden 2000)

No formal management plan has been implemented.

Aspects of this species reproductive biology and ecology, demographic patterns and habitat requirements would aid in conservation efforts.

Detailed germination studies are needed.