Description of Turbinicarpus laui

Photo © Mark Faint

Latin: Caulis solitarius, subglobosus vel globose depressus, a 35 mm latus et 15 mm longus; costae in tubercula divisae, in 5-8 lineas spirales instructae; color caulium virens; tubercula rhomboidea, 5 mm alta, basi 10 mm lata, conica; areolae floriferae extensionem parvam areolum spiniferum formantes, 1 mm longae, primum dense albo laniferae, seinde nudae; spinae 6, interdum 7 vel rarius 8, albae, vitreae, apice nigrescentes, aciculares, rigidae, leviter recurvatae, radiantes; spinae tres inferiores a 5 mm longae, superiores laterales a 7 mm; superiores (una vel duo) Ca. 18-22 mm in longitudinem fere incurvatae, supra apicem caulis conniventae, sed interdum strictae vel tortuosae; flores magni, albi vel fere rosei, 35 mm lati, 18 a 25 mm longi; perianthii segmenta forma variabilia, 2.5 a 5.0 mm lata, apice lata rotundato, acuto; segmenta exteriora lata abaxiale lineam mediam brunescentem exhibenda; stylus albus vel pallide roseus, lobis 3-6 albescentibus, antheras excedentis; stamina numerosa, filamentis roseis, antheris aureis, a 12 mm longa; fructus parvi, rotundi, Ca. 5 mm diametientes, per scissuram longitudinem dehiscentes; semina parva, nigra.

Stem solitary, sub-globose to depressed globose, to 35 mm wide and up to 15 mm high; ribs divided into tubercles, arranged in 5 and 8 spirals with 3 or 4 tubercles per spiral, dull medium green, to 5 mm high, rhomboidal and to 10 mm broad at base, conoidal; flowering areoles a small, upper extension of spine areoles, ca. 1 mm long, copiously woolly with thick, long, white wool in youth, soon becoming bare; spines 6, occasionally 7, and occasionally with an additional upper (sub-central) spine, glassy white with blackish tip, slender acicular, relatively stiff and slightly recurved, spreading, radiating; lower three spines to 5 mm long, upper lateral spines to 7 mm long, upper spine (s) ca. 18-22 mm long and generally incurved, connivent over the top of the stem, or occasionally erect to somewhat tortuous; flowers large, white or with a pink cast, 35 mm wide, ca. 18 to 25 mm long; perianth segments variable in shape, from 2.5 to 5 mm broad, tip acute to broadly rounded, occasionally with a slightly darker pale pink or pale tan mid-stripe; outer segments with a brownish mid-stripe on the outer surface; style white to pale cerise with 3 to 6 whitish stigma lobes which overtop anthers; stamens numerous with pale cerise filaments and golden yellow anthers, the longest to about 12 mm long; fruit small, round, greenish to brown, ca 5 mm in diameter, dehiscent by a longitudinal slit; seed small, 1.1 mm long, tuberculate, black.

Locality: near Buena Vista, San Luis Potosi, México.

Notes

Clarke Brunt has some habitat photos of this taxon on his Mexican homepage.

Related taxa

Turbinicarpus laui is part of the lophophoroides aggregate of taxa, together with the following:

• T. lophophoroides
• T.lophophoroides var. jauernigii
• T. hoferi
• T. swobodae

References

• Turbinicarpus laui A new species from San Luis Potosi, CASJ(US), Vol 47(3): 116-119, 1975

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