Sedum laxum

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

6a. Sedum laxum (Britton in Britton & Rose 1903: 29) Berger (1930: 451) subsp. heckneri ( Peck 1937: 121) Clausen (1942: 39) . Figs. 4A , 6D , 30

Sedum heckneri Peck (1937: 121) . Sedum laxum (Britton) A.Berger var. heckneri (M.Peck) Ohba (2007: 889) .

Type: — UNITED STATES. California: Siskiyou Co., [published in error in the protolog as Jackson Co. , Oregon, see Clausen (1975: 391)], dry cliff along [Middle Fork] Applegate River, 4 miles above mouth of Carberry Creek , 26 June 1931, M. E . Peck 16421 (holotype, WILLU) .

Additional specimens examined: — UNITED STATES. CALIFORNIA. Del Norte County: NW of Cedar Camp Spring , 1220 m, 8 June 1983, Imper s.n. ( WTU) ; Six Rivers National Forest , S of Flint Valley, 1340 m, 27 July 1982, Imper s.n. ( WTU) ; Six Rivers National Forest , N of Bluff Creek, 823 m, 30 July 1982, Imper s.n. ( WTU) . Humboldt County: S of Grizzly Camp , 1370 m, 5 September 1948, Tracy 18190 ( SD, UC, WTU) ; Klamath River , 305 m, June 1901, Chandler 1439 ( UC) ; S of Somes Bar , 21 June 1954, Hitchcock 20219 ( WS) ; Willow Creek Canyon, 305 m, 3 July 1944, Tracy 17488 ( UC) ; near Aikens Campground , 170 m, 25 June 1976, Denton 3976 ( WTU) ; SW of Hoopa , 260 m, 25 June 1976, Denton 3974 ( WTU) ; N of Hoopa , 240 m, 25 June 1976, Denton 3975 ( WTU) ; Salmon Summit , 1770 m, 30 July 1935, Tracy 14363 ( UC, WTU) ; Hoopa , 425 m, 4 July 2012, Wilson, Otting & Darington CWG-119 ( OSC, “ SRNF,” WTU) ; E of Weitchpec , 137 m, 29 June 2013, Wilson et al. CWG-236 ( HSC) ; road to E-Ne-Nuk Campground , 122 m, 29 June 2013, Wilson et al. CWG-237 ( JEPS) . Siskiyou County: E of Forks of Salmon , 26 June 1937, Eastwood & Howell 5056 ( CAS) ; N Fork Salmon River , 675 m, 19 June 2014, Wilson 18109 & Otting ( OSC) ; Whites Gulch , 770 m, 19 June 2014, Wilson 18108 & Otting ( OSC) ; N of Clear Creek , 22 May 1961, Hutchison 2036 ( JEPS) ; near Upper Devils Peak , 1342 m, 7 August 1979, Clifton 12757 ( UC) ; SW of mouth of Carberry Creek , 700 m, 4 July 1976, Denton 4014 ( OSC, WTU) ; Middle Fork of Applegate River , 760 m, 5 August 1962, Hutchison 958 ( BH, SD) ; same site, 670 m, 4 July 1976, Denton 4016 ( WTU) ; same site, 670 m, 11 July 1991, Kagan 7-11-91-01 ( OSC) ; same site, 19 July 2011, Zika 25641 ( CAS, RSA) ; Slater Butte , 1067 m, 4 June 1947, Detling 6120 ( ORE) ; Salmon Mountains, N of Hancock Lake , 2105 m, 11 July 1969, Oettinger 988 ( RSA) ; Middle Fork of Applegate River, Whiskey Creek trail, 915 m, Rolle s.n. ( OSC) ; Siskiyou Mountains , NW of Abney Butte, 675 m, 19 July 2011, Zika 25640 ( BH, HSC, SD, UCR) ; Antenna Ridge , 1305 m, 12 July 2014, Otting 3841 ( HSC, SOC, UBC, WTU) . OREGON. Jackson County: Whiskey Peak, 1931, Nye s.n. ( ORE) ; Upper China Gulch , May 1984, Rolle s.n. ( OSC) ; Carberry Creek, Steve Fork , 790 m, 12 June 1991, Zika 11199 ( BH, OSC) ; Siskiyou Mountains , SE of Steve Peak, 830 m, 19 July 2011, Zika 25653 ( BH, CAS, OSC, RSA, UCR, WTU) ; E of Steve Peak , 780 m, 19 July 2011, Zika 25652 ( CAS, GH, MICH, RM, RSA, UC, WTU). Josephine County: above China Flat , 1095 m, August 1962, Hutchison 956 ( BH, JEPS) ; Slickrock Creek , 900 m, August 1962, Hutchison 955 ( JEPS) ; Wingdam Gulch , 1 August 1980, Garcia 185 ( OSC) ; Whiskey Peak , July 1932, Nye 5 ( ORE) .

Distribution and ecology: — Sedum laxum subsp. heckneri ( Fig. 27 ) ranged from Jackson County, Oregon, to Humboldt County, California, at lower elevations, in the Klamath Ranges ecoregion, and the northern edge of the Outer North Coast Ranges in California (Jepson eFlora 2017). Most populations were on rocky slopes, rubble, and cliffs, at elevations of 190–2104 m. Some colonies were on slopes with seasonal subsurface water flow. It was also found on roadcuts, which other Sedum section Gormania infrequently colonized. Some populations disappeared in recent years.

The chromosome voucher Goodspeed s.n. (BH 81412) cited by Clausen (1942), and in Table 3, had the morphology and cytology of Sedum laxum subsp. heckneri , not S. eastwoodiae . The herbarium label location (“Mendocino Co.”) appeared to be an error (see Results).

Notes: — Sedum laxum subsp. heckneri ( Fig. 30 ) had blue-green or pinkish foliage. The stem leaves were usually suborbicular (rarely oblong), usually reflexed or spreading, with clasping, auriculate bases. The sides of the stem leaves were often planar, but were often oriented slightly downward, giving the whole leaf a saddle-like shape. A few plants in the Applegate River drainage rarely had oblong, somewhat reflexed stem leaves. The sepals were relatively short and often acuminate. The petals were acuminate and pink with white margins, and erect or nearly so at anthesis. The fresh anthers were red to dark red, senescing black.

The chromosome counts, flowers and inflorescences of Sedum laxum subsp. heckneri were identical to those of subsp. laxum . S. laxum subsp. heckneri was distinguished by reflexed, suborbicular, auriculate stem leaves. Stem leaves of subsp. laxum were elliptic to oblong, ascending to spreading, and truncate-based, not auriculate, though sometimes decurrent. The two subspecies of S. laxum were allopatric ( Fig. 27 ).

Sedum laxum subsp. heckneri had acuminate slender erect petals 7–13 mm, and the stems were often elongate, (9) 13–29 cm tall. In these characters it differed from S. eastwoodiae , which had relatively broader, more acute and ascending petals 4–9 mm, and stems 4–13 cm tall. The two were allopatric ( Fig. 27 ) and had different ploidy levels ( Table 3), though they shared similar-shaped stem leaves and pink flowers ( Table 6). In addition to the differences emphasized in the key, the inflorescences of subsp. heckneri , in all but depauperate plants, were much larger than the inflorescences of S. eastwoodiae .

Figures

FIGURE 4. Water stored in the stem leaves appeared to be used in the reproductive effort. Stem leaves withered as flowering progressed. Proximal stem leaves shriveled before those near the inflorescence. A. Sedum laxum subsp. heckneri, Siskiyou Co., California; proximal stem leaves withered, distal still plump (Zika 25640). B. Sedum patens, Del Norte Co., California; proximal stem leaves shriveling during anthesis (Zika 26608 & Brainerd). C–D. Sedum rubiginosum, Tehama Co., California. C. Turgid stem leaves at the initiation of flowering (Wilson & Coberly CWG-10). D. Shriveled stem leaves at late anthesis (Zika 26234). E. Sedum sanhedrinum, Tehama Co., proximal stem leaves withering first (Zika 25970).

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 27. Distribution of the pink-flowered taxa Sedum eastwoodiae, S. laxum subsp. heckneri, and S. laxum subsp. laxum, based on verified herbarium specimens.

FIGURE 30. Sedum laxum subsp. heckneri. A. Dense rosettes, Siskiyou Co., California (Zika 25640). B–D. Stem leaves, clasping at base, nearly as long as wide, spreading, ascending, or descending. B, D. Jackson Co., Oregon (Zika 25652). C. Siskiyou Co. (Wilson 18109 & Otting). E. Habit, in flower. F. Flat-topped inflorescence, pink flowers. E–F. Siskiyou Co. (Wilson 18108 & Otting). G. Pink erect acuminate petals, dark red anthers, acuminate sepals; Siskiyou Co. (Zika 25640).