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ROBERTSIANUM Alexander, 1936

Synonym : Sedum parvum ssp. robertsianum  (Alexander) R. T. Clausen (1981)


Distribution : USA (Texas : Brewster County), adjacent Mexico (Coahuila) ; shallow calcareous soil, ± 1300 m.



Description (according to IHSP, 2003) :


Glabrous perennial herbs with caespitose fleshy stems, branched at the base, with numerous decumbent branchlets 8 - 12 cm long.


Leaves alternate, ovoid, apiculate, appearing minutely papillose (caused by reflection of the inner facets of windowed cells), turgid, 5 - 8 mm, 3 - 4 mm wide and thick, yellow-green.


Inflorescences : Flowering branches erect, axillary, inflorescences cymes, simple or with 2 branches, sometimes with short branches at the base with solitary flower, bracts leaf-like but much smaller.


FIowers 5- (rarely 4-) merous, sessile or subsessile, sepals unequal, the 2 outer much larger than the inner, lanceolate, ± 2 mm, petals lanceolate, canaliculate, ± 4 mm, bright yellow.


Cytology : 2n = 28


According to Charles Uhl, this species is only distantly related to S. parvum and should not be included in the synonymy of this species as IHSP suggests (Rhodora 87, 1985).

Photo Ray Stephenson

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