Rare Plant List
County List
Agency Status
Photo List
About the List
History of Changes
Species Considered, but dropped
Photographers, Illustrators and Authors
Image Usage Guidelines
Discussion Group
Useful Literature

About the Rare Plant List

The primary goal of the New Mexico Rare Plant Technical Council is to develop and maintain a list of New Mexico rare plants. Criteria for inclusion of taxa, and an explanation of the R-E-D Code are on this page.

Criteria for Inclusion

Having a consistent and objective definition of rarity is necessary to evaluate all the species proposed as potentially rare. Plants with narrow habitat specificity and small range are automatically of concern, whether their populations are large or not. Other categories are less clearly rare. A wide range and a narrow habitat are rare if the total number of populations is small. Plants that occur only in small populations are rare if the number of those populations are limited. Disjunct populations with numerous populations outside the state of New Mexico are cases where in a global view, the plants are not rare.

The NMRPTC will take a biological outlook and try not to read evolutionary potential into plant populations. The NMRPTC will include sparse plants, those with large ranges but narrow habitats, and those of small ranges and narrow habitats. Some widespread but sparse plants will be included on the basis of threats to their survival.


As a general rule, the NMRPTC treats hybrid species--those that originated through hybridization but now form populations that are reproductively independent from their parents--simply as species like any other. Ephemeral hybrids that form in contact zones between their parents and are either infertile or interbreed freely with one or both parents, on the other hand, are not considered eligible for listing as rare by the NMRPTC. Complicated situations are evaluated on a case-by-case basis. As an example, Opuntia viridiflora may have originated by hybridization between Opuntia imbricata and Opuntia whipplei. Regardless of this possible hybrid origin, current populations are fertile and reproductively independent; consequently O. viridiflora is listed as a rare plant. Sporadic, morphologically similar hybrids that occur in areas where O. imbricata and O. whipplei are sympatric, and which do not form such reproductively independent populations, are not considered by the NMRPTC to be O. viridiflora.

RARE = A taxon that is narrowly endemic to a specific geographic feature (e.g., mountain range; geologic outcrop) or subset area of a phytogeographic region (e.g., southern Rocky Mountains, northern Chihuahuan desert). It can be locally abundant within its narrow range, but typically will not extend more than 100 miles in length of range; OR A taxon that is more widespread, but is numerically rare - never locally common - throughout its range (e.g., Peniocereus greggii) or is numerically abundant only in a few small, widely scattered habitats (e.g., Puccinellia parishii, Helianthus paradoxus).

The R-E-D Code

The R-E-D Code concept has been so useful to the California Native Plant Society in developing the Inventory of Rare, Threatened and Endangered Plants of California (CNPS, 1994), that we developed a system that is similar, but is slightly different for the rarity ranking. This code presents a three element ranking that gives a great deal of information about each plant in a glance. The three components are rarity, endangerment and distribution that together form the R-E-D Code. Each element in the code is divided into three classes or degrees of concern, represented by the number 1, 2 or 3. In each case, the higher the number, the more critical the concern. The system is defined as follows:

R (Rarity)

1: rare, but found in sufficient numbers and distributed widely enough that the potential for extinction is low for the foreseeable future
2: occurrence confined to several populations or to one extended population
3: occurrence limited to one or a few highly restricted populations, or present in such small numbers that it is seldom reported

E (Endangerment)

1: not endangered
2: endangered in a portion of its range
3: endangered throughout its range

D (Distribution)

1: more or less widespread outside New Mexico
2: rare outside New Mexico
3: endemic to New Mexico

About the Map Data

In using this web site you may discover some differences between the reports and their distribution maps. Location information shown on the maps was obtained from herbarium specimen records, agency databases, and the scientific literature. Some map points may represent data entry errors or misidentified specimens in our herbaria, which highlights the need to re-examine specimens and annotate them where appropriate. Other map points may represent range extensions that were unknown to the author of the report. Resolving cases where reports and maps differ is an ongoing process and we will modify our web site as these differences are identified and resolved. Please contact us if you have information that will help in this effort.

Photo credits in header Peniocereus greggii var. greggii © T. Todsen,
Lepidospartum burgessii © M. Howard, Argemone pleiacantha ssp. pinnatisecta © R. Sivinski
Design: J. Mygatt; Copyright © 1999-2005 New Mexico Rare Plant Technical Council