Stebbinsoseris heterocarpa
Stebbinsoseris
brown microseris, derived silverpuffs, grassland silverpuffs, grassland stebbinsoseris
silverpuffs
0, or erect, mostly unbranched, glabrous or lightly scurfy-puberulent.
usually all basal; petiolate (petioles narrowly attenuate, usually scurfy-puberulent, especially proximally);
blades linear to narrowly oblanceolate, bases slightly clasping, margins entire or irregularly dentate or lobed (teeth and lobes narrow, acute, straight or arcuate, faces glabrous or minutely scurfy-puberulent).
5–60 cm.
not notably inflated, usually ebracteate (glabrous or ± scurfy-puberulent, especially distally).
6–30 mm.
campanulate, (3–)5–35 mm diam. (fusiform to ovoid in fruit).
flat, ± pitted, glabrous, epaleate.
10–125;
corollas yellow or white.
(10–)30–125;
corollas yellow or white, outer often purplish abaxially (equaling or surpassing phyllaries by 1–3 mm).
(4–)5–18 in ± 2 series, (green or purple) mostly lanceolate, subequal to equal, herbaceous, apices acute, faces glabrous.
of (3–)4–14, deltate or ovate to lanceolate bractlets.
borne singly (often inclined in bud, erect in flowering and fruit).
gray, straw-colored, brown, or violet (dark purplish in southwest California), narrowly truncate-fusiform to columnar, 4.5–12 mm, each filled by embryo or distal 0.5–3 mm vacant and more slender than proximal part, apices slightly widened at bases of pappi;
pappi 7–19 mm, scale bodies 4–11 mm, faces usually glabrous, rarely villous, aristae 3–8 mm.
brown, purplish gray, stramineous, or violet, sometimes purple-spotted, columnar or truncate-fusiform, not beaked, ribs 10, ± scabrellous or spiculate, faces glabrous or (on outer) strigose;
pappi persistent, of 5, usually yellowish or brownish, rarely white, aristate scales (bodies straight or arcuate, lanceolate, usually glabrous, margins plane or involute, apices erose or notched, aristae shorter than to equaling bodies, barbellulate).
= 18.
= 36.
Stebbinsoseris heterocarpa
Stebbinsoseris
Stebbinsoseris heterocarpa is widespread in cismontane California and disjunct to Gila and Yavapai counties, Arizona. Variation in enzymatic restriction sites in its chloroplast DNA and nuclear rDNA (R. S. Wallace and R. K. Jansen 1995) indicates that S. heterocarpa has arisen independently three or more times from hybrids of Microseris douglasii × Uropappus lindleyi. Reflecting this multiple origin, the species is more variable in pappi and cypsela size, color, and shape than S. decipiens, from which it is largely allopatric. Because M. douglasii subsp. tenella and M. bigelovii intergrade in some coastal areas, forms of S. heterocarpa having such hybrids as their maternal parent would be difficult to distinguish from S. decipiens (K. L. Chambers 1955; U. Lohwasser and F. R. Blattner 2004).
(Discussion copyrighted by Flora of North America; reprinted with permission.)
Species 2 (2 in the flora).
Stebbinsoseris comprises two allotetraploid species derived from hybrids between Microseris and Uropappus. The justification for raising these species to generic rank was given in R. K. Jansen et al. (1991b), where molecular data were presented supporting the separation of Uropappus from Microseris. Stebbinsoseris and Uropappus were ranked as sections of Microseris in earlier taxonomic treatments (K. L. Chambers 1955, 1960). Because of its hybrid origin, Stebbinsoseris is intermediate in critical taxonomic traits of habit, involucre, and fruits (C. Irmler et al. 1982), and it is separated from its parental taxa by rather minor differences. Chloroplast DNA studies show that Microseris douglasii and M. bigelovii were the maternal parents of the tetraploid hybrids (R. S. Wallace and R. K. Jansen 1990). That Uropappus lindleyi was the staminate parent of those crosses is confirmed by nuclear rDNA evidence reported by Wallace and Jansen (1995).
(Discussion copyrighted by Flora of North America; reprinted with permission.)
1. Cypselae narrowly truncate-fusiform, brown to purplish, 5–8 mm, apices not widened at bases of pappi; pappus scale bodies 3–5 mm; coastal central California | S. decipiens |
1. Cypselae narrowly truncate-fusiform to columnar, gray to pale brown or violet (dark purplish in sw California), 4.5–12 mm, apices slightly widened at bases of pappi; pappus scale bodies 4–11 mm; widespread, rarely coastal except in sw California | S. heterocarpa |
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