Synonyms:
Yucca rupicola var. rigida Engelmann, Trans. Acad. Sci. St. Louis, 3: 49 (in part)
Yucca rostrata Engelmann ex Trelease, Rep. Miss. Bot. Gard. 13: 68 (1902), (in part)

Hybrids:
Yucca 'thompsonifolia HORT, (2002) in Yucca II, Hochstätter hybrid (Yucca thompsoniana x Yucca recurvifolia).
Yucca filamentosa x thompsoniana, Made by Ruud Wouterson, The Netherlands in 2008.

Type location:
Bufatello, near Presidio del Norte, Rio Grande, Chihuahua, Mexico.

Distribution:
Texas, Val Verde Co, Terrell Co., Brewster Co., Trans Pecos Region, Mexico, Chihuahua, Coahuila. at 300 1500 m.

Short description of the species:
Plants arborescent with 1 to 3 stems up to 250 cm tall and 128 to 15 cm thick, rosettes with up to 30 leaves. Leaves, bluish-green, 25 - 45 cm long, up to 1 cm wide, margin of the leaves yellow to brownish with short sharp "teeth's". Inflorescence paniculate, glabrous or sometimes pubescent, 100 to 200 cm tall. Scape held high above the leaves 38 to 70 cm long. Branchlets  20 to 35, 2 to 22 cm long. Flowers globose (round) to campanulate (bell shaped), 3 to 6 cm long, white. Fruit 3 to 6 cm long, 1 to 2 cm thick. Seeds black, dull, 0,5 to 0,6 x 0,6 to 0,7 cm, without marginal wing.

Hardiness:
Not Known

Related species:
Yucca cernua, status not sure, maybe a natural hybrid with genes from Yucca rupicola or Yucca pallida?
Yucca reverchoni
Yucca rostrata
Yucca rupicola
Yucca pallida

Pictures:
I do not have any pictures of this species in bloom or in habitat, if you have a photo that I may use please let me know
 

Yucca thompsoniana Grown in Alexander Heim's garden in his Greece. Copyright 2008 Alexander Heim.

Notes:
Yucca thompsoniana is not only very related to Yucca rigida If you go to the location for the type specimen for Yucca thompsoniana (Bufatello, near Presidio del Norte, Rio Grande, Chihuahua, Mexico.) what you will see there is plants of what we today call Yucca rigida. Since Yucca rigida was published first, then it does have priority as a species rank, and the plant we call Yucca thompsoniana is actually a unnamed species! The original description of Yucca thompsoniana was actually intended to describe plants from the Stockton Plateau. But the plant chosen as type specimen was a plant which actually were a Yucca rigida growing a far  away from it's distribution area. Hopefully will Hochstätter have solved this error in his next book the Yuccas of Mexico, which will be published in 2004 or before in one of his many articles in the Dutch Journal Succulenta.

Reference:
ENGELMANN, Trans. Acad. Sci. St. Louis, 3: 49 (1873)
HOCHSTAETTER, F., Succulenta, Netherlands, Vol. 78 no. 5, 207-217, Yucca (Agavaceae) part 5.
HOCHSTAETTER, F; (2000), YUCCA (vol. I): 28-29.
TRELEASE, Rep. Miss. Bot. Gard. 13: 68 (1902)
TRELEASE, Rep. Miss. Bot. Gard., 22: 101 ff. 104, fig. 1, 105, 106, 107, fig. 1 (1911)