Sedum flavidum ( Denton 1978: 233 ) B.L. Wilson & Zika, 2018

Zika, Peter F., Wilson, Barbara L., Brainerd, Richard E., Otting, Nick, Darington, Steven, Knaus, Brian J. & Nelson, Julie Kierstead, 2018, A review of Sedum section Gormania (Crassulaceae) in western North America, Phytotaxa 368 (1), pp. 448-450 : 448-450

4. Sedum flavidum ( Denton 1978: 233) B.L. Wilson & Zika , comb. nov., stat. nov. Figs. 1A , 6A–C , 12 , 13A , 14A–B , 15B , 28 .

Sedum laxum (Britton in Britton & Rose 1903: 29) Berger (1930: 451) subsp. flavidum Denton (1978: 233) (basionym). Sedum laxum (Britton) A.Berger var. flavidum (Denton) Ohba (2007: 889) .

Type: — UNITED STATES. California: Trinity Co., 4.5 miles NE of Forest Glen along Post Creek , 914 m, 23 June 1976, M. F . Denton 3953 (holotype, WTU; isotype, NY) .

Additional specimens examined:— UNITED STATES. CALIFORNIA. Colusa County: Mendocino National Forest , W of Upper Letts Lake, 1480 m, 24 June 2013, Elliott 13 ( CHSC, KANU, MICH) ; same site, 12 June 2014, Zika 26643 & Brainerd ( SD, OSC, WTU) ; WSW of Upper Letts Lake , 1480 m, 12 June 2014, Zika 26642 & Brainerd ( WTU) ; W of Big Spring picnic area, 1480 m, 1 July 2012, Wilson & Otting CWG-114 ( JEPS, RSA, WTU) . Glenn County: SE of Mendocino Pass , 1798 m, 23 June 1961, Uhl 970 ( BH) ; Black Butte , 31 miles E of Covelo, 2134 m, 20 June 1976, Denton 3941 ( OSC, WTU) ; SE of Plaskett Meadows Campground , 1880 m, 2 July 2012, Wilson & Otting CWG-115 ( KANU, MO, US, WTU) ; road to Black Butte Lookout , 2155 m, 2 July 2012, Wilson & Otting CWG-116 ( OSC, WTU) . Humboldt County: Grouse Mountain , 1524 m, 25 July 1933, Tracy 12899 ( UC [2 sheets]) ; near Sims Mountain , 430 m, 15 July 1980, Newton 1549 ( UC, WTU) ; same site, 17 July 2013, Darington 13- SM ( HSC, JEPS, SBBG) ; Pilot Creek Quadrangle, 300 m, 15 July 1980, M. Baker 2941 ( UC, WTU) ; near Red Mountain , 11 July 1980, M. Baker 2769 ( UC) ; Lacks Creek area on Pine Ridge Road , 1032 m, 9 June 2012, Brainerd & Otting CWG-103 ( OSC, WTU) ; Titlow Hill Road above junction with Route 299, E of Arcata, 23 June 1990, Chambers 5511 ( OSC) ; Lassics Botanical Area , 26 July 2012, L. D. Hoover LDH-1 ( OSC) ; Horse Mountain , S of Berry Summit, 21 May 1961, Hutchison 2013 [= Uhl 932] ( JEPS) ; Horse Mountain , 1435 m, 9 July 1947, Tracy 17865 ( UC) ; same site, 4 July 2012, Wilson, Otting, & Darington CWG-118 ( GH, HSC, MO, WTU) ; Supply Creek, Hoopa , 730 m, 4 July 2012, Wilson, Otting & Darington CWG-120 ( OSC) ; G-O Road , 1465 m, 20 June 2014, B. L. Wilson 18112 ( OSC) ; Klamath River , 1.4 miles S of Siskiyou County line, 150 m, 10 July 1961, Roderick 61.989 ( JEPS) ; Highway 299, 595 m, 29 June 2013, Wilson et al. CWG-238 ( RSA) . Trinity County: Post Creek , 885 m, 13 June 1951, Moran 3484 ( BH, CAS, UC) ; Klamath Mountains, North Post Creek , 885 m, 13 June 1963, Clausen 63199 ( BH) ; same site, 17 June 1963, Clausen 63200 ( BH) ; same site, 18 June 1963, Clausen 63202 ( BH, GH) ; Post Creek , 915 m, 22 June 1976, Denton 3949 ( OSC, WTU) ; Post Creek , 853 m, 23 April 1977, Denton 4066 ( WTU) ; same site, 19 June 2011, Wilson & Coberly CWG-07 ( OSC, UCR, WTU) ; Salt Creek , 945 m, 13 June 1951, Moran 3483 ( BH, CAS) ; same site, 13 June 1963, Clausen 63195 ( BH) ; same site, 19 June 1963, Clausen 63197 ( BH) ; E of Mud Springs , 1 July 1979, Baker 608 ( CAS) ; S of Peanut , 945 m, 25 June 1980, Denton 4189 ( WTU) ; Blue Point , 8 June 2012, J. K. Nelson JKN-12-2 ( CHSC, HSC) ; Bule Gulch , 917 m, 19 June 2011, Wilson & Coberly CWG-06 ( CAS, JEPS) ; N of Hackney Spring , 1375 m, 19 June 2011, Wilson, Coberly & J. K. Nelson CWG-08 ( KANU, MO, NY) ; road to Hell-to-Find Lake , 1295 m, 19 June 2011, Wilson, Coberly & J. K. Nelson CWG-09 ( DAV, RSA, US) ; W of Wildwood , 945 m, 13 June 1937, Wolf 8799 ( OSC) ; ENE of Limedyke Mountain , 1200 m, 22 June 2012, Zika 25922 & J. K. Nelson ( DAV, HSC, WTU) ; NE of Red Mountain , 1260 m, 12 June 2014, Zika 26646 & Brainerd ( WTU) .

Distribution and ecology: — Sedum flavidum populations ranged in elevation from 231–1707 m. The species was variable in floral and stem leaf characters. Some of the variation was roughly correlated with three geographic areas in California ( Fig. 25 ). A cluster of populations occurred in southern and eastern Trinity County, usually on serpentine substrates in the Klamath Ranges ecoregion. Closer to the coast were the western-most populations in Humboldt and southwestern Trinity counties. These plants were in the outer North Coast Ranges and the High North Coast Range ecoregions (Jepson eFlora 2017). Disjunct southern populations occurred in Glenn and Colusa counties, in the High North Coast Ranges ecoregion. We could not separate those populations in the PCoA analysis, and did not provide them with different taxonomic ranks here. Nonetheless, we felt they deserved further study, especially in the western and southern extremes of the range.

Notes: — Sedum flavidum ( Fig. 28 ) had obtuse to notched dense rosette leaves. The stem leaves were typically small, suborbicular and slightly auriculate, but sometimes were elliptic to oblong. The stem leaves were flattened, planoconvex, or saddle-shaped, and varied in aspect, usually spreading, but occasionally ascending or slightly reflexed. The sepals were short relative to the petals. The petals of wild plants were usually ascending, and usually broad in the distal half ( Fig. 12 ), obtuse to acute, white to pale yellow, sometimes red or pink along the midrib, occasionally also near the base, senescing white or pink to red, at least towards the base. The fresh anthers were yellow, aging white, pink, or brown.

We treated Sedum flavidum as different at the species level from the subspecies of S. laxum . They differed in ploidy level; 2n = 30 in S. laxum and 2n = 60 in S. flavidum ( Table 6). Sedum flavidum corollas were white or pale yellow, with yellow anthers, while in S. laxum the fresh anthers were dark red, and the flowers were pink, or primarily pink with white margins ( Table 6), though cultivated plants sometimes produced nearly white flowers ( Fig. 16B ). Sedum flavidum also differed in its blunter sepals, and had more acute and ascending petals ( Denton 1979b). The suborbicular stem leaves of S. flavidum resembled those of S. laxum subsp. heckneri but tended to be smaller and ascending to spreading, less commonly reflexed. Also, elliptic to oblong stem leaves occur in S. flavidum populations in Colusa, Glenn, and southern Trinity counties; in S. laxum subsp. heckneri , the proportionately longer stem leaves are known only from a few plants in the Applegate River drainage.

Denton (1978) described Sedum laxum subsp. flavidum and placed it within S. laxum on the strength of leaf flavonoids, similar glaucous leaf surfaces, rosette leaf shape, rosette density, petal length to width ratio, and stigma diameter ( Denton 1982). However, Denton & Kerwin (1980) identified their flavonoid voucher (Denton 4048) as S. laxum subsp. laxum ; we annotated it to diploid S. oregonense . In addition, the flavonoids said to unite the subspecies of S. laxum (3,7-disubstituted kaempferol, laricytrin, and an unidentified flavone) were not restricted to this group, but were also found in S. moranii , S. oblanceolatum , and some populations of S. oregonense . Neither S. moranii nor S. oblanceolatum were closely related to S. flavidum ( Table 5). Similarly, we found the morphological characters used by Denton (1982) did not uniquely define S. laxum , but were shared with additional species. The petal length/width ratio of S. flavidum was shared with S. oregonense , and the rosette characters were similar in S. obtusatum .

Three populations in Colusa and Glenn counties, California, resembled Sedum flavidum populations near the type locality in having ascending, acute, white petals (sometimes marked with pink), proportionately short sepals, and suborbicular to oblong stem leaves. These plants were disjunct from the main range of S. flavidum as currently defined, and grew fairly close to S. sanhedrinum populations. They should be studied further.

Although the two were allopatric, Sedum flavidum was sometimes difficult to distinguish from S. oregonense morphologically, and their flowers were similar. Ecologically, S. flavidum was found at lower and more forested elevations, and further south. Many populations of S. flavidum had suborbicular slightly clasping stem leaves, at least some years, while this was uncommon to rare in S. oregonense . The two differed in the density and aspect of their vegetative shoots. Sedum flavidum had compact rosettes on short lateral shoots when growing in sunny exposed situations, sometimes forming dense mats of nearly uniform leaves ( Fig. 1A ). Sedum oregonense had loose rosettes with obvious internodes, on numerous elongate lateral shoots or stolons when growing in sunny exposed microsites ( Fig. 2D ).

Figures

FIGURE 1. Dense rosettes on vegetative shoots, without visible internodes between the leaves, were found in most species. A. Sedum flavidum, Trinity Co., California (Zika 26646 & Brainerd). B. Sedum laxum subsp. laxum, Del Norte Co., California (Zika 25927). C. Sedum oblanceolatum, Jackson Co., Oregon (Zika 25636 & Lang). D–E. Sedum rubiginosum, Tehama Co., California. D. Wild plant (Zika 26238). E. Cultivated plant (Wilson & Coberly CWG-10). F. Sedum sanhedrinum, Mendocino Co., California (Zika 26629 & Brainerd).

FIGURE 2. In full sun, loose open rosettes, with easily visible internodes, were characteristic of sterile shoots for three species. A–B. Sedum citrinum, Del Norte Co., California (Zika 26185). C. Sedum kiersteadiae, diffuse habit with numerous stolons typical of this species and the next, Siskiyou Co., California (Zika 26289). D. Sedum oregonense, Clackamas Co., Oregon (Zika 25964).

FIGURE 6. Suborbicular stem leaves were typically found in Sedum laxum subsp. heckneri, S. eastwoodiae, in many populations of S. flavidum, and in scattered populations of S. oregonense. The leaf base was often slightly clasping on suborbicular stem leaves. Stem leaf shape varied across populations, growing seasons, and on individual stems. A–C. Sedum flavidum. A–B. Trinity Co., California (Zika 25922 & J.K. Nelson). C. Humboldt Co., California (Wilson, Otting, & Darington CWG-118). D. Sedum laxum subsp. heckneri, Jackson Co., Oregon (Zika 11199). E–G. Sedum oregonense. E–F. Clackamas Co., Oregon (Zika 25964). G. Del Norte Co., California (Zika 25928).

FIGURE 12. Variation in the width of the distal half of the petal in Sedum flavidum. A. Narrow-petaled extreme, Humboldt Co., California (Wilson 18112). B–D. Variation within a population, Trinity Co. (Zika 25922 & J.K. Nelson). B. Narrow-petaled extreme. C. Slightly narrowed petals. D. Typical broad petals. E. Slightly narrowed petals, Trinity Co., California (CWG-102a).

FIGURE 13. Distal half of the petals broad and ascending. A. Sedum flavidum, Trinity Co., California (J.K. Nelson JKN-12-2). B. Sedum obtusatum, Nevada Co., California (Zika 26271). C. Sedum oregonense, Del Norte Co., California (Otting CWG-122). D. Sedum paradisum subsp. subroseum, Plumas Co., California (Wilson, Janeway & Zika CWG-14).

FIGURE 14. Cultivated individuals often had petals more widely spreading than in the wild. A–B. Sedum flavidum corollas, Humboldt Co., California (Brainerd & Otting CWG-103). A. Ascending petals, wild plants. B. Spreading petals, cultivated plants. C–D. Sedum laxum subsp. laxum corollas, Del Norte Co., California. C. Erect petals, wild plants (Brainerd & Otting CWG-107). D. Ascending petals, cultivated plants (Brainerd & Otting CWG-104). E–F. Sedum sanhedrinum corollas, Tehama Co., California. E. Erect petals, wild plants (Zika 26244). F. Ascending petals, cultivated plants, Tehama Co. (J.K. Nelson JKN-2).

FIGURE 15. The color of the petals, anthers, filaments, and carpels often changed after anthesis.A. Sedum albomarginatum, after anthesis petals turned orange-brown; Butte Co., California (Zika 25867). B. Sedum flavidum, buds deep pink especially along the keel, faded to white at anthesis, then aged to a uniform deep pink; Humboldt Co., California (Wilson, Otting, & Darington CWG-118). C. Sedum laxum subsp. laxum, after anthesis green carpels turned dark red, red anthers turned white; Del Norte Co., California (Zika 25936). D. Sedum paradisum subsp. subroseum, after anthesis green carpels turned dark red, yellow anthers turned white; Plumas Co., California (Wilson, Zika & Janeway CWG-15). E. Sedum rubiginosum, after anthesis red-based yellow petals turned pallid; Tehama Co., California (Zika 26234).

FIGURE 16. Some taxa occasionally produced paler flowers in cultivation.A–B. Sedum laxum subsp. laxum. A. Pink petals, wild plants, Del Norte Co., California (Zika 25927). B. Fresh white petals with faint pink background, turning darker pink with age, cultivated, from Josephine Co., Oregon (Zika 25487). C–D. Sedum paradisum subsp. paradisum, Shasta Co., California. C. Yellowish petals, fading pinkish-orange, wild plants (Zika 25924). D. White petals, cultivated (Lindstrand III & Van Susteren NSR-07).

FIGURE 25. Distribution of Sedum flavidum, S. kiersteadiae, S. rubiginosum, and S. sanhedrinum, based on verified herbarium specimens.

FIGURE 28. A comparison of Sedum flavidum populations from three portions of its range.Toprow, A–E.Northwestern portion of range, Humboldt Co., California (Wilson, Otting, & Darington CWG-118). A. Dense rosettes formed a mat. B–C. Inflorescences with white petals, yellow anthers. B. Stem leaves about as wide as long. C. Stem leaves longer than wide. D. Variant of corolla color, petals with pink midvein in bud and pinkish blush in bloom, more pronounced as the flowers faded. E. Typical corolla color, ascending white petals, distal half slightly narrowed, yellow anthers. Center row, F–L. Central portion of range, including the type locality, Trinity Co., California. F. Dense rosettes (Zika 25922 & J.K. Nelson). G–J. Variation in stem leaf shape. G. Rosette and flowering stem (Wilson, Coberly & J.K. Nelson CWG-08). G–H. Stem leaves longer than wide, truncated at base. H. (Zika 26646 & Brainerd). I. Stem leaves broadest above the middle, clasping at base, somewhat reflexed, type locality (Wilson & Coberly CWG-07). J. Stem leaves suborbicular, clasping at base (Zika 25922 & J.K. Nelson). K. Variant of corolla color, petals pale yellow-orange, fading pinkish (Zika 26646 & Brainerd). L. Typical flowers, broad ascending white petals, yellow anthers (Zika 25922 & J.K. Nelson). Bottom row, M–R. Southern portion of range, Colusa Co., California. M. Dense rosettes (Zika 26642). N. Flowering stems, stem leaves suborbicular (Wilson & Otting CWG-114). O. Stem leaves elliptic, truncated at base, planoconvex (Zika 26642). P. Stem leaf suborbicular, ± planar (Zika 26642). Q. Variant of corolla color, petals white with dark pink midveins in bud, faded pink, petal tips broad and ascending (Zika 26642). R. Typical flowers, broad ascending white petals, yellow anthers (Zika 26642).