Sedum citrinum Zika (2014: 112)

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

2. Sedum citrinum Zika (2014: 112) . Figs. 2A–B , 5A , 8B , 9A , 11A , 23 , 24A .

Type: — UNITED STATES. California: Del Norte Co., ridge N of South Red Mountain , 1050 m, 9 June 2013, P. F . Zika 26185 (holotype, WTU; isotypes, BH, CAS, GH, MO, OSC, RSA, UC, US) .

Additional specimens examined:— UNITED STATES. CALIFORNIA. Del Norte County: near Red Mountain lookout, 1220 m, 26 June 1979, Overton & Butler 6664 ( HSC); N of South Red Mountain , 1050 m, 24 June 2012, Zika 25930 ( HSC, JEPS, SBBG, UCR); same site, 9 June 2014, Zika 26611 & Brainerd ( OSC, WTU); NNW of South Red

Mountain , 1210 m, 24 June 2012, Zika 25931 ( DAV, MO, NY, US); same site, 9 June 2013, Zika 26193 ( BH, CAS, WTU) ; NW of South Red Mountain, 1235 m, 9 June 2013, Zika 26201 ( BH, CAS, RSA, WTU); N of Red Mountain, 1190 m, 10 June 2014, Zika 26619 & Brainerd ( WTU) ; Turwar Creek drainage, NNW of Red Mountain Lookout, 1235 m, 10 June 2014, Zika 26615 & Brainerd ( HSC, RSA, US); same site, 940 m, 10 June 2014, Zika 26620 & Brainerd ( OSC, WTU) .

Distribution and ecology:— Sedum citrinum was endemic to gently sloping ultramafic outcrops and meadows at elevations of 940–1275 m in southern Del Norte County, California, where it was recorded from a few populations within an area of fifteen square km near South Red Mountain ( Fig. 22 ), in the western Klamath Ranges ecoregion (Jepson eFlora 2017). Its ecology was summarized in Zika (2014).

Notes:— Sedum citrinum ( Fig. 23 ) had thick obovate rosette leaves and thick oblong to elliptic or obovate stem leaves ( Fig. 5A ). The sepals were relatively short ( Fig. 9A ). The petals were deep yellow, narrow, and strongly spreading, often to 90° from the flower axis ( Figs. 8B , 11A ). Fresh anthers were yellow, aging to yellow, white, brown, or orange. The inflorescences were flat-topped or rounded, with elongate lower branches, not columnar or cylindrical as in the closely related species S. kiersteadiae and S. rubiginosum ( Fig. 24 ). The three taxa were allopatric.

Sedum citrinum was similar to the recently described S. kiersteadiae , a more widespread species of the Cascade Range Highlands and Klamath Ranges ecoregions (Jepson eFlora 2017), from Siskiyou County, south to Trinity and Shasta counties ( Fig. 25 , Wilson et al. 2014). Both had narrow, widely spreading, yellow petals and vegetative shoots with well-spaced leaves in open rosettes. Sedum citrinum differed from S. kiersteadiae in inflorescence shape and also in flower color, which was paler in S. kiersteadiae . Sedum citrinum was also similar to S. rubiginosum of Tehama County, California. The latter was restricted to the extreme southern tip of the Klamath Ranges ecoregion, 150 km southeast of S. citrinum ( Fig. 25 ), and had dense rosettes with larger, columnar inflorescences with more numerous and more densely crowded flowers.

Figures

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 5. Stem leaves longer than wide, with a truncated base, were typical of most species of Sedum section Gormania. The stem leaves were commonly broadly obovate to elliptic or oblong, and were flattened or nearly cylindrical.A. Sedum citrinum, Del Norte Co., California (Zika 26185). B. Sedum laxum subsp. laxum, Del Norte Co. (Zika 25927). C. Sedum oblanceolatum × oregonense, Siskiyou Co., California (Zika 25647B). D. Sedum obtusatum, Nevada Co., California (Zika 26271). E–F. Sedum oregonense, Josephine Co., Oregon (Zika 25657). G. Sedum sanhedrinum, Lake Co., California (Zika 26639 & Brainerd).

FIGURE 8. The central basal flower in a cyme was the largest and opened first.A. Sedum albomarginatum, Plumas Co., California (Zika 25865). B. Sedum citrinum, Del Norte Co., California (Zika 26201). C. Sedum laxum subsp. laxum, Del Norte Co. (Zika 25927). D. Sedum paradisum subsp. paradisum, Shasta Co., California (Lindstrand III & Van Susteren NSR-01). E. Sedum patens, Del Norte Co. (Zika 26609 & Brainerd).

FIGURE 9. The sepals were short compared to the length of fresh petals in most species. In all species the sepals elongated after anthesis, as the petals wilted. A–C. Relatively short sepals in early anthesis. A. Sedum citrinum, Del Norte Co., California (Zika 26193). B. Sedum oregonense, Jackson Co., Oregon (Zika 25666 & Wilson). C. Sepals elongating post-anthesis, Sedum oblanceolatum, Siskiyou Co., California (Zika 25650A). D–F. Relatively long sepals in early anthesis. D–E. Sedum paradisum subsp. paradisum. D. Shasta Co., California (Lindstrand III & Van Susteren NSR-8). E. Trinity Co., California (Zika 25920 & J.K. Nelson). F. Sedum paradisum subsp. subroseum, Sierra Co., California (Zika 26279).

FIGURE 11. Petal tips narrow in the distal half; the petals strongly spreading to slightly reflexed. A. Sedum citrinum, Del Norte Co., California (Zika 26620 & Brainerd). B. Sedum kiersteadiae, Trinity Co., California (Zika 26294). C. Sedum patens, Del Norte Co. (Zika 26609 & Brainerd). D. Sedum rubiginosum, Tehama Co., California (Zika 25522 & J.K. Nelson).

FIGURE 22. Distribution of Sedum albomarginatum, S. citrinum, S. marmorense, S. moranii, S. oblanceolatum, and S. patens, based on verified herbarium specimens.

FIGURE 23. Sedum citrinum, Del Norte Co., California.A. Habit (Zika 26611 & Brainerd). B. Inflorescence nodded in bud, rosettes were loose (Zika 26193). C. Rosette leaves, lower row; stem leaves, upper row (Zika 25930). D–E. Deep yellow flowers with spreading narrow petals, yellow anthers faded white. D. Zika 26619 & Brainerd. E. Zika 26620 & Brainerd.

FIGURE 24. Inflorescence comparison between Sedum citrinum, S. kiersteadiae, and S. rubiginosum. All three species with narrow spreading yellow petals. A. Sedum citrinum, inflorescence with elongated lower branches, flat-topped, Del Norte Co., California (Zika 25930). B. Sedum kiersteadiae, cylindrical and loose inflorescence, individual flowers easily seen, Shasta Co., California (Zika 26294). C–D. Sedum rubiginosum, cylindrical and dense inflorescence, individual flowers less easily distinguished, Tehama Co., California (Zika 25522 & J.K. Nelson).

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