Sedum acre
Sedum robertsianum
goldmoss stonecrop, moss stonecrop, mossy stonecrop, orpin acre, orpin âcre, wall-pepper
trailing (nonflowering shoots ascending at tip), laxly branched, not bearing rosettes.
decumbent, branched basally, (fleshy), with numerous decumbent branchlets, not forming rosettes.
erect, usually simple, 5–10(–15) cm;
leaf blades triangular-ovate, base short-spurred;
offsets not formed.
(axillary), erect, simple or branched, 5–10 cm;
leaf blades ovate, base not spurred;
offsets not formed.
(usually deciduous, if persistent, then blade white, soft, papery), alternate, (densely imbricate), spreading, sessile;
blade yellow-green, not glaucous, triangular-ovate, terete to semiterete (elliptic in cross section), (2–)5(–8) × 1–4 mm, base obtusely short-spurred, not scarious, apex obtuse.
(persistent), alternate, spreading, sessile;
blade yellow-green, not glaucous, ovate, subterete, somewhat flattened, 5–8 × 3–4 mm, (thick, turgid), base not spurred, not scarious, apex apiculate, (surfaces minutely papillose, caused by reflections of inner facets of windowed cells).
cymes, 2–12-flowered or flowers solitary, monochasially (1–)2(–3)-branched;
branches not recurved, rarely forked;
bracts similar to leaves, smaller.
cymes, 6–12-flowered, simple or 2-branched, sometimes with short branch at base with solitary flower;
branches not recurved, sometimes forked;
bracts similar to leaves, smaller.
absent or to 1 mm.
absent or to 0.5 mm.
5-merous;
sepals erect to spreading, distinct basally, green, oblong-ovate, unequal, 2–3 × 1.3–2.3, mm, apex obtuse;
petals spreading, distinct, bright yellow, oblong-ovate to lanceolate, not carinate, 5–9 mm, apex acute to acuminate;
filaments yellow;
anthers yellow, (oblong);
nectar scales yellowish green, square.
(4–)5-merous;
sepals spreading to reflexed, distinct, yellow-green, lanceolate, unequal, ca. 2 × ca. 0.8 mm, apex obtuse;
petals spreading, nearly distinct, bright yellow, lanceolate, canaliculate, ca. 4 mm, apex acute;
filaments color unknown;
anthers color unknown;
nectar scales pale yellow, oblong.
stellately patent in fruit, distinct, yellowish.
spreading, distinct, tan to reddish.
= 40, 60, 80, 100, 120.
= 28.
Sedum acre
Sedum robertsianum
Sedum acre is native in Greenland. It is naturalized in North America across the northern United States and southern Canada from Quebec to North Carolina in the east and from British Columbia to Oregon in the west. Sedum elrodii was found near Somers in Flathead County, Montana. It is known only from a fragmental type specimen. R. T. Clausen (1975) considered it a naturalized form of S. acre with ovate leaf blades, basally connate petals, and procumbent and branched stems from a fleshy rootstock.
(Discussion copyrighted by Flora of North America; reprinted with permission.)
Sedum robertsianum occurs in the Del Norte and Glass mountains of Brewster County.
Sedum robertsianum is a somewhat confusing taxonomic entity. In a treatment contributed in the 1970s for the Flora of the Chihuahuan Desert Region (M. C. Johnston and J. S. Henrickson, in prep.), R. T. Clausen placed S. robertsianum in synonymy with Mexican S. parvum but did not assign it to subspecies status. However, only subsp. nanifolium occurred in both Texas and Mexico. Later, Clausen (1981) made S. robertsianum a subspecies of S. parvum. In a study of the systematics of the S. parvum complex, G. L. Nesom and B. L. Turner (1995) treated S. robertsianum as a species of uncertain status. They cited specimens from the Del Norte Mountains (the type locality of S. robertsianum, see Clausen 1981) as S. nanifolium, which they elevated from S. parvum subsp. nanifolium. It is possible that there are two species of yellow-flowered sedums within one mountain range in western Texas. It is also possible that there is only one species, and either S. robertsianum is synonymous with S. nanifolium, or it is a distinct species and the only Sedum in the Del Norte Mountains of western Texas.
(Discussion copyrighted by Flora of North America; reprinted with permission.)
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