Sedum album Linné, 1753

Mifsud, Stephen, Stephenson, Ray & Thiede, Joachim, 2015, Sedum album subsp. rupi-melitense (Crassulaceae), a new vegetatively reproducing subspecies from Malta (Maltese Islands, Central Mediterranean), Phytotaxa 227 (2), pp. 135-146 : 138-139

Sedum album Linné subsp. rupi-melitense Mifsud, Stephenson & Thiede, subsp. nov. – Figs. 3–5

Type:—MALTESE ISLANDS. Malta: Misraħ Għar Daqquq (close to Ġebel Ciantar [ Fig. 1 , locality 7]), Fawwara, Siġġiewi, on the edge of coastal cliffs of upper coralline limestone, 200 m, 29 May 2013, S. Mifsud SMIFS-17 (holotype E!).

– Sedum glanduliferum sensu Gulia (1874: 417) , non Gussone 1827. – Sedum dasyphyllum sensu Sommier & Caruana Gatto (1915: 151) and Haslam et al. (1977: 91), non Linné 1753. – Sedum album sensu Hart & Berg (1982: 680 , 691) pro parte (Maltese plants); sensu Greuter et al. (1986: 186) pro parte (Maltese plants);

sensu Jalas et al. (1999: 98) pro parte (Maltese plants); sensu Lanfranco (1989:17, 2001:16); sensu Mifsud (2007; with ills.); sensu

Darmanin (2009 with ill.); sensu Marhold (2011) pro parte (Maltese plants); sensu Casha (2013: 313 with ills.). – Sedum aff. album sensu Stephenson (2014 ; with ill.).

Diagnosis: — Differs from Sedum album subsp. album in having very rarely formed inflorescences which are normally without peduncular leaves and floral bracts or, if present, only small and vestigial; flowers in which (3–)5 stamens of one whorl, mostly of the antepetalous one, have dysfunctional and often abortive anthers; retained anthers dark maroon to blackish-brown and mostly indehiscent at anthesis; pollen which is partly deformed and shrivelled; carpels without nectary scales; and fruits and seeds which remain undeveloped and sterile ( Table 1).

Description: — Perennial herbs, succulent, laxly caespitose with creeping sterile shoots up to 25 cm long, stems densely glandular-hairy at base (insertion of lower leaves), sparingly above and at hardened part of stem below the leaves .. Leaves 3.0–7.0 × 1.0– 2.5 mm, alternate, sessile, spreading and becoming imbricate-appressed distally, linearelliptic to ovoid, terete to semiterete and flattened adaxially with obtuse tip, not or scarcely spurred at base, green, not glaucous, tinged amber to cinnabar red in the upper third during summer; very sparingly papillate, papillae irregularly arranged, <10 per leaf, absent on some leaves. Inflorescences very rarely formed, erect, up to 15 cm tall, dense cymes 3–8 cm broad, usually with 5–10 primary branches, glabrous, rugulose; peduncular leaves reduced in number or mostly missing; bracts vestigial, caducous, tiny or scale-like (about 1 mm), reduced in number or mostly missing. Flowers pedicellate by 1–2 mm; 5–6 mm diameter, 5-merous with 5 sepals, 5 petals, 10 stamens in 2 whorls, and 5 carpels. Sepals basally fused, equal, broadly ovate to sub-orbicular, marginally imbricate, 1.5–2.0 mm long, pale greyish-green, rarely pale red at upper part. Petals free, lanceolate, spreading, obtuse to subacute, 3.5 × 2.0 mm, wax-white, with a midvein sometimes pale pink at the lower half. Stamens obdiplostemonous, filaments 3 mm, white, (3–)5 filaments of one whorl, mostly of the antepetalous whorl, with dysfunctional and often abortive anthers, filaments of the other whorl with 5 functional anthers, in total 5(–7) filaments with functional anthers, anthers basifixed, cylindrical, 0.6–0.8 mm long, dark maroon to blackish-brown. Carpels free, 3.0–3.5 × 1.0 mm, white, adaxial side papillate and slightly pink, style to 0.5 mm long, at first erect, later curving outwards, stigma inconspicuous, nectary scales absent. Fruits undeveloped, soft and shrivelled. Seeds undeveloped, sterile. Chromosome number 2n = 136 ( Hart & Berg 1982, as S. album ).

Distribution and ecology: — Assuming that all previous records of S. dasyphyllum and S. album from Malta are attributable to S. album subsp. rupi-melitense, its distribution on the Maltese Islands is as follows (! = studied in habitat; †= recently extinct; Fig. 1 ):

Figures

FIGURE 1. Distribution of Sedum album subsp. rupi-melitense on Malta (UTM, zone 33S, 1x1 km grid). The localities are enumerated from N to S and W to E (see text). Diamonds refer to literature records or personal communications confirmed during field surveys between 2012–2014, circles to new records, question marks (?) to unconfirmed literature records or personal communications, and a cross for a population which became extinct early this year.

FIGURE 3. Vegetative parts of Sedum album subsp. rupi-melitense. 3A. Habit of a specimen with greenish leaves taken in Winter.— Malta, Wied Diegu, Żurrieq [Fig. 1, locality 11], 11 January 2014. 3B. Close-up of green leaves in winter.—Malta, Wied Fulija, Żurrieq [Fig. 1, locality 10], 11 January 2014. 3C. Habit and leaves in spring.—Malta, Wied Diegu, Żurrieq, 10 April 2014. 3D. Close-up of leaves showing the reddish colouring in its upper half.—Malta, Wied Diegu, Żurrieq, 29 May 2012. 3E. Macrophotograph showing the glandular hairs on the stem. 3F & 3G. Macrophotographs showing the sparse papillae on the leaves.—Photographs by S. Mifsud.

FIGURE 4. Inflorescences and flowers of Sedum album subsp. rupi-melitense. 4A. Inflorescence.—Malta, Wied Diegu, Żurrieq [Fig. 1, locality 11], 16 April 2014. 4B. Inflorescence.—Malta, Rdum Dikkiena, Siġġiewi [Fig. 1, locality 6], 19 June 2012. 4C. Mature flower with five antheriferous stamens.—Malta, San Ġorġ tal-Fawara, Siġġiewi [Fig. 1, locality 7], 30 May 2013. 4D. Immature flower forced open with ten antheriferous stamens of which five (here: the antesepalous ones) are shrivelled and caducous.—Malta, Wied Diegu, Żurrieq, 15 June 2014.—Photographs by S. Mifsud.

FIGURE 5. Inflorescences and dissected flower parts of Sedum album subsp. rupi-melitense. 5A. Inflorescence without peduncular leaves or floral bracts or if present, these are vestigial and scar-like. 5B. Dissected flower parts, top to bottom: petals (3.5 mm long); stamens (3 mm); carpels (3.5 mm) and sepals (ca. 1.5 mm). Malta, San Ġorġ tal-Fawara, Siġġiewi [Fig. 1, locality 7] (30 May 2013).—Photographs by S. Mifsud (30 May 2013).