Flora

The Sierra Bacha is in the Central Gulf Coast Subdivision of the Sonoran Desert along the coast of the Gulf of California, south of Puerto Libertad, Municipality of Pitiquito, Sonora. The flora of the Sierra Bacha has 269 species, one additional subspecies, and one hybrid in 57 families and 183 genera. The most species-rich families are Asteraceae (44 species); Fabaceae (23 species); Euphorbiaceae (17 species); Boraginaceae, Cactaceae, Poaceae, and Solanaceae (15 taxa each).

We report 431 taxa in 269 genera and 69 families for the Tónichi area. The most diverse families are Fabaceae (61 taxa); Poaceae (40 taxa); Asteraceae (36 taxa); Euphorbiaceae (27 species); Malvaceae (22 species); Convolvulaceae (20 species); Solanaceae (18 species); Boraginaceae (15 species); Apocynaceae and Cactaceae (11 species each); and Acanthaceae and Nyctaginaceae (10 species each).

The Sierra La Púrica is a Sky Island mountain range north- northwest of Nacozari de García (municipality of the same name), Sonora, Mexico, in the Área de Protección de Flora y Fauna Bavispe in the Comisión Nacional de Áreas Naturales Protegidas. The Madrean Archipelago Biodiversity Assessment Expedition Sierra La Púrica took place in July and September 2013. The preliminary flora contains 306 plant taxa in 215 genera and 71 families. Families with the most taxa were Poaceae (49 taxa), Asteraceae (43 taxa), and Fabaceae (32 taxa).

The trans-border flora of the San Bernardino National Wildlife Refuge in Arizona and Rancho San Bernardino in Sonora has 541 taxa in 316 genera and 86 families. The most diverse families are Poaceae (88 taxa), Asteraceae (84 taxa), Fabaceae (28 species), Euphorbiaceae (24 species), Amaranthaceae (18 species), Boraginaceae and Solanaceae (17 species each), and Brassicaceae (15 species).

This magnificent flora of the Sonoran Desert’s southern edge represents decades of meticulous work and the genius of Richard Felger (1934–2020) and his colleagues at their best. It is many things at once.

Thirty-eight plant taxa are reported for Sonora, Mexico, for the first time. Specimens, observations, and images are deposited in herbaria and are available in the SEINet online databases.

The flora of the lower Río Bavispe Valley from the Huásabas area south to the Río Áros at 430 to 1,510 m. elevations (1,410 to 4,954 ft.) was studied from 1995 to 2016. A total of 401 plant taxa in 74 families and 274 genera were recorded in the lower Río Bavispe Valley study area, including 24 non-native species (6.0%). The families with the most species were Asteraceae (50), Fabaceae (50), Poaceae (42), Euphorbiaceae (20), Malvaceae (19), Cactaceae (13), Solanaceae (15), and Pteridaceae (11), representing 54.9% of the flora.

The Municipio de Yécora is in the Tropical Madrean zone of the Sierra Madre Occidental in eastern Sonora, Mexico. The flora is very diverse with 1777 taxa in 150 families and 687 genera. The most important families and genera are Asteraceae (14.5% of the flora), Poaceae (11.3%), and Fabaceae (10.6%), Muhlenbergia (38 taxa), Euphorbia (31 taxa), Cyperus (29 taxa), Ipomoea (26 taxa), Quercus (23 taxa including 7 hybrids), and Dalea (22 taxa). Herbaceous plants dominate the flora (71.3%).

An introduction is provided for the modern and fossil vascular plant flora of the contiguous protected areas of Organ Pipe Cactus National Monument, Cabeza Prieta National Wildlife Refuge, and the Tinajas Altas Region in southwestern Arizona—the heart of the Sonoran Desert. These three entities encompass 514,242 hectares (1,270,700 acres), approximately 5141 km (1985 mi ). Elevation and ecological diversity generally decreases from east (Organ Pipe) to west (Tinajas Altas) while aridity increases from east to west, both correlating with decreasing botanical diversity.