Other Scientific Names: Nephropetalum pringlei
Other Common Names: Tamaulipan kidneypetal, Rio Grande ayenia
Status:Federal and State Endangered
Global Rank: G2
State Rank: S1
Global Location: Texas ayenia grows in south Texas in Cameron, Hidalgo, and Willacy counties, as well as in northern Mexico in Coahuila, Durango, and Tamaulipas.
Description: Texas ayenia is a 1.5 m tall, thornless shrub with heart-shaped leaves that have saw-toothed edges. Older stems of Texas ayenia have rust-colored spots, which are variable in shape (round to linear). Arising from the stem at the same point as the 3.5-12.5 cm long by 2-7.5 cm wide leaves, the small, yellowish-green flowers hang in clusters of three (rarely four). Petals are U-shaped with the base of the U attached to the flower. The small round fruits are prickly and have five lobes, which break apart into five sections when the fruit dries.
Texas ayenia has prickly fruit and heart-shaped leaves with saw-toothed edges.
Texas ayenia flowers have yellowish-green, U-shaped petals.
Similar Species: Hairy ayenia (Ayenia pilosa) is much smaller (10-20 cm tall), has reddish, triangular petals, and two different leaf shapes (lower leaves are more round and upper leaves are more egg-shaped). Texas ayenia can be distinguished from other similar-appearing mallows by its prickly, 5-sectioned fruit, and the reddish-brown spots on its older stems. If flowers are present, these species can easily be differentiated from one another.
Habitat: This plant can be found on well-drained soils in subtropical thorny woodlands and tall shrublands of the Rio Grande delta.
Image courtesy of Lisa Williams.
Life Cycle Events: Flowering can occur throughout the year with adequate rainfall.
Survey Season: As a woody perennial, Texas ayenia can be recognized year-round, although identification may be easier when flowers and or fruits are present.
Comments: In 1994, when Texas ayenia was listed as endangered, there was one known site in South Texas. However, 25 new sites have been found in both the Rio Grande Valley and in northern Mexico. Although newly located populations of Texas ayenia have increased the plantís chance of recovery, habitat loss and encroachment of invasive grasses are severe enough that this species continues to be listed as endangered.
For additional information see:
U.S. Fish and Wildlife Service
Center for Plant Conservation
As Nephropetalum pringlei in: Correll, D.S. and M.C. Johnston. 1970. Manual of the Vascular Plants of Texas. Texas Research Foundation. Renner, TX.
Pronatura Noreste, A.C. 2005. Status, distribution, and conservation of three species of rare plants in the Lower Rio Grande in Mexico. Section 6 final report. Austin: Texas Parks & Wildlife Department.