(Photograph = Yucca treculeana)
Yucca treculeana grows in south Texas and is the only tree yucca that grows east of the Pecos River. It can form a tall plant to 15-ft tall (even 20-ft tall is claimed for exceptional specimens).
Y. treculeana grows from the coastal flats of the south Texas Gulf Coast along the Rio Grande River counties to New Mexico. Of course it grows more deeply into Mexico. Along the coast the plant can grow in sandy dunes, and it grows taller toward the coast. The leaves are thick and concave, very long and thin, with a sharp tip. Overall, the leaves are sharp and dagger like.
If there has been enough rain, the plant blooms in different parts of the year, but the heaviest bloom is in spring. Y. treculeana is more tolerant of moist soils than other tree yuccas, but it still requires good drainage.
Typically the plants are solitary and branch one or a few times. However, small thickets of Y. treculeana have been reported. Y. treculeana is not deer proof, but it is highly deer resistant. Y. treculeana may be the same taxon as Y. torreyi.
Additional Reading: Chihuahuan Desert Yuccas in Cultivation