Daviesia sejugata Chandler & Crisp (1997: 33)

Crisp, Michael D., Cayzer, Lindy, Chandler, Gregory T. & Cook, Lyn G., 2017, A monograph of Daviesia (Mirbelieae, Faboideae, Fabaceae), Phytotaxa 300 (1), pp. 448-450 : 448-450

9. Daviesia sejugata Chandler & Crisp (1997: 33) , Craigie (2015: 32). Type: Tasmania, Milford Estate, 7-mile Beach Road, Cambridge, 42°48’30’S, 147°30’30’E, D.L. Jones 13473, 8 October 1994. Holotype: CANB; isotypes: AD, HO, K

Divaricate shrubs to 2 m high, sometimes wider than high, usually glabrous, rarely hispid on inflorescence axes. Root anatomy unknown. Branchlets spinescent, prominently longitudinally ridged, angular. Phyllodes scattered, spreading to ascending, narrowly elliptic to obovate, pungent, articulated at base, (8–)15–33 × (1.5–) 2.5–5.5 mm, thick and wrinkled in appearance when dry; upper (adaxial) face ± flat or convex with midrib more prominent than on abaxial face. Unit inflorescences 1 or 2 per axil, umbellate, 2–5-flowered; peduncle 1–1.5 mm long; subtending bracts ca. 1–1.5 mm long. Pedicels 2–4.5 mm long. Calyx campanulate, 3–4.5 mm long including ca. 1 mm receptacle; lobes equal, broadly triangular, slightly but clearly recurved, ca. 0.7–1.5 mm long, faintly ribbed. Corolla : standard very broadly obovate, emarginate, ca. 6–7 × 6.5–7.5 mm including ca. 2–2.5 mm claw (claw absent in Yorke Peninsula specimens), rich yellow with maroon infusion surrounding the intensely yellow centre; wings obovate, apically rounded, auriculate, ca. 6.3 × 2–2.5 mm including ca. 2–2.5 mm claw, red with orange infusion at tips; keel half transversely broadly obovate, acute, auriculate, ca. 5 × 2 mm including ca. 2 mm claw, dark purple. Stamens strongly dimorphic: inner whorl of 5 with longer, slender filaments and shorter, rounder, basifixed anthers with confluent thecae; outer whorl of 5 with shorter, broader, compressed filaments and longer, versatile, 2-celled anthers; filaments free. Style curving gently upwards through 90°, not hooked. Pod obliquely shallowly obtriangular, acuminate, 8–11 × 4–6 mm; upper suture sigmoid; lower suture ca. 90°. Seed ellipsoid, 2.5– 3 mm long, 1.2–1.5 mm wide, ca. 1.3 mm thick, orange-brown to tan with black mottling (rarely not); aril ca. 1.5 mm long. ( Fig. 10 ).

Flowering period:— September and October. Fruiting period: unknown.

Distribution:— Disjunct on southern Yorke Peninsula and Kangaroo Island, South Australia, and in northern and eastern Tasmania.

Habitat:— On southern Yorke Peninsula, this species grows in mallee-heath dominated by Eucalyptus diversifolia Bonpland (1814: 35) and Melaleuca lanceolata Otto (1820: 36) on grey, stony calcareous soil. In Tasmania, it grows on sand in the heathy understorey of open forest dominated by eucalypts such as E. obliqua L’Héritier de Brutelle (1789: 18) , E. viminalis Labillardière (1806 : t. 151) and E. amygdalina Labillardière (1806 : t. 154).

Conservation status:— National: Not listed. SA: Endangered but the species occurs commonly in Tasmania.

Selected specimens (31 examined):— Approximate locality data are given for SA because the species is rare there. SOUTH AUSTRALIA. Yorke Peninsula: vicinity of Marion Bay , 35°10’S, 137°00’E, B . Copley 4751, 9 September 1975 ( AD); ibid., R . Bates 842, 21 September 1980 ( AD, OSA). Kangaroo Island: near Cape du Couedic , P. G . Wilson 718, 4 November 1958 ( AD, B, K, SI). TASMANIA. King Island , near southern portion, P . Barnett s.n., 28 October 1968 ( MEL 0080557 A); Epping Forest , 41°46’S, 147°21’E, R . Gunn s.n., 17 October 1842 ( CBG 7801704 ); near Port Arthur , ca. 43°09’S, 147°51’E, A. V . Giblin s.n., 23 October 1929 ( HO 10191 ); 1.5 km N of Cape Queen Elizabeth, Bruny Island , J. H . Hemsley 6243, 6 October 1967 ( HO 10197 , MEL 0080558 A) .

A MONOGRAPH OF DAVIESIA

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36 • Phytotaxa 300 (1) © 2017 Magnolia Press

CRISP ET AL.

Affinity:— Daviesia sejugata shows a close resemblance to D. arthropoda , though it is closer to D. ulicifolia ( Fig. 1A ). The phyllodes of D. sejugata resemble those of D. arthropoda , though they vary from elliptic (or narrowly so) to obovate. Daviesia arthropoda and D. sejugata differ in the surface of the phyllode—that of D. sejugata appears wrinkled when dry because of its thickness, whereas that of D. arthropoda is thinner and not so wrinkled. The unit inflorescence of D. arthropoda is umbellate like that of D. sejugata but distinctly longer (peduncle 4–8 mm and pedicel 3–8 mm). The standard of D. sejugata is wider than that of D. arthropoda , in which the flowers tend to be quite small by comparison (e.g. calyx 3–3.5 mm long, standard ca. 4 × 3 mm). Finally, D. arthropoda has differently coloured flowers from D. sejugata , being predominantly yellow to somewhat orange, with diffuse red, generally paler, markings. Specimens of D. sejugata from Yorke Peninsula, South Australia, have consistently obovate phyllodes and a sessile standard as in D. arthropoda , but clearly fit D. sejugata in flower colour, robustness of the phyllodes, and in the shorter peduncles and pedicels.

The most reliable feature to diagnose D. sejugata from D. ulicifolia is the calyx, which is campanulate with broadly triangular, scarcely keeled lobes that are erect or slightly recurved from the base. By contrast, the calyx of D. ulicifolia is elliptic or obovate in outline, evenly curved from the tube to the lobes (which may be slightly recurved at the tips), and the lobes are narrow and strongly keeled. The phyllodes of D. ulicifolia are usually smaller than those of D. sejugata (with those of D. ulicifolia being ca. 5–17 mm long, occasionally up to 22 mm), and tend towards ovate rather than elliptic or obovate shapes, although elliptic phyllodes are not uncommon in some subspecies, such as subsp. pilligensis . The inflorescence varies in D. ulicifolia , and is often 1-flowered, but when umbellate tends to have shorter peduncles (up to 3 mm, though normally shorter) than in D. sejugata . Some of the subspecies of D. ulicifolia have large flowers as in D. sejugata , but then they are often predominantly red or orange (e.g. D. ulicifolia subsp. incarnata , subsp. aridicola and subsp. ruscifolia ), whereas those of D. sejugata are predominantly yellow (as in D. ulicifolia subsp. ulicifolia, subsp. stenophylla and subsp. pilligensis ).

In Tasmania, small-leaved plants of D. sejugata can be difficult to distinguish from the local form of D. ulicifolia subsp. ulicifolia . Nevertheless, the calyx characters described above distinguish the species in Tasmania too. The Tasmanian form of D. ulicifolia s.s. is usually hispid on the branchlets, whereas D. sejugata is always glabrous. The unit inflorescences of D. sejugata are distinctly pedunculate and 3- or more-flowered whereas those of D. ulicifolia s.s. are more or less sessile and usually 1- or 2-flowered. Daviesia sejugata is an altogether more rigid, robust, divaricate and diabolically prickly plant than D. ulicifolia . Daviesia ulicifolia subsp. ruscifolia also occurs in Tasmania but is easily distinguished from D. sejugata by its 1-flowered inflorescence, calyx (as in subsp. ulicifolia ) and ovate to broadly ovate phyllodes.

Figures

FIGURE 1A. Phylogeny (part) of Daviesia estimated using maximum likelihood (PHYML) from concatenated sequences of ITS (nrDNA), and ndhF and trnL–trnF (cpDNA). The tree was rooted using the monotypic sister groups Viminaria and Erichsenia (not shown). The informal clade names are used for reference in the taxonomic treatment. Numbers on branches show non-bootstrap support. The tips are labelled with the taxon name and sample accession number.

FIGURE 10. Daviesia sejugata. Holotype. Photograph provided by the Curator of CANB.