Daviesia retrorsa Crisp (1995: 1228)

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

97. Daviesia retrorsa Crisp (1995: 1228) . Type: Western Australia, Roe, main Balladonia–Esperance track, near turn-off to Mt Ragged , M.A. Clements 2051, 17 August 1980. Holotype: CBG; isotypes: K, MEL, PERTH

220 • Phytotaxa 300 (1) © 2017 Magnolia Press

CRISP ET AL.

A MONOGRAPH OF DAVIESIA

Phytotaxa 300 (1) © 2017 Magnolia Press • 221 Dense, hummocky, intricate shrubs, to 1.6 m high and 3 m broad; branchlets and phyllodes glabrous, smooth when fresh, lightly ribbed or wrinkled when dry, dull green or glaucescent. Root anatomy with anomalous secondary thickening (cord type). Branchlets ascending or tangled, often gently sinuous, tending to flexuose when juvenile, terete. Phyllodes scattered, sometimes very few present and only near branchlet apex, spreading at ca. 90° or retrorse, terete, tapered gently from the articulate base to the acicular, pungent apex, 5–50 mm long, 1–1.5 mm diam. Seedling phyllodes narrowly obovate for the first 7 or 8 nodes before grading into terete phyllodes over the next 2–4 nodes; those at lower 7 or 8 nodes with a petiole-like base, prominent reticulate venation, mucronate, 16– 30 × 1.5–3.5 mm; upper juvenile phyllodes to 35 × 0.5 mm, terete, mucronate. Unit inflorescences 1 per axil, racemose, 2–5-flowered; peduncle 1–7 mm long; rachis 0.5–6 mm long; subtending bracts spreading to ascending, oblong, keeled, ca. 1 mm long. Pedicels 3–6 mm long. Calyx 3.5–4 mm long including the ca. 1.5 mm receptacle; lobes ca. 0.75 mm long; upper 2 lobes united into a truncate lip; lower 3 lobes triangular, recurving just below the lobes. Corolla : standard depressed-ovate, emarginate, 6–6.5 × 7.5–9 mm including the ca. 1.5 mm claw, orange-yellow with a red central ring around a yellow centre; wings spathulate, apically rounded and incurved but not overlapping, auriculate, ca. 5–5.5 × 3 mm including the 1.5 mm claw, light red; keel half transversely elliptic, acute to slightly obtuse, neither incurved nor beaked, auriculate, saccate, ca. 4.5–5 × 2 mm including the 1.5 mm claw. Stamens strongly dimorphic: inner whorl of 5 with longer, slender filaments and round, versatile anthers with confluent thecae; outer whorl of 5 with shorter, broader, compressed filaments and oblong, basifixed, 2-celled anthers; filaments all compressed, free. Pod obliquely shallowly obtriangular, acuminate, somewhat turgid, 9–11 × 6–7 mm, thick-walled; upper suture strongly sigmoid; lower suture acute and very broadly rounded. Seed obloid to ± globose, 3.5–4 mm long, 2.5–3 mm broad, 2–2.5 mm thick, brown to black with brown mottling; aril ca. 2–2.3 mm long. ( Fig. 98 ).

Flowering period:— August to November. Fruiting period: August to November.

Distribution:— Western Australia, along the south coast from Hopetoun east to the track from Cocklebiddy to Twilight Cove on the Great Australian Bight.

Habitat:— White sand over limestone, on dunefields or rocky outcrops, in eucalypt mallee-heath or Acacia heath.

Selected specimens (20 examined):— WESTERN AUSTRALIA. Eyre: Cape Arid National Park , 33 km WNW of Israelite Bay, 33°32’S, 123°31’E, R . Borough 3, 1 September 1978 ( CBG); 12 km from Mt Ragged (Tower Peak) Range along road to Israelite Bay , 33°33’S, 123°31’E, M . D. Crisp 4859, 6 January 1979 ( CBG, MEL); Cape Arid National Park , E of Esperance, R . D. Royce 10136, 5 December 1971 ( PERTH); 7 km from Esperance along road to Ravensthorpe , 33°46’S, 121°50’E, J . Taylor 1614 & P . Ollerenshaw, 10 September 1983 ( CBG, MEL). Eucla: 20 km SSW of Cocklebiddy along track to Twilight Cove , 32°12’S, 126°04’E, M . D. Crisp 4772, 4 January 1979 ( CBG, K, MEL, PERTH). CULTIVATED. Australian National Botanic Gardens , ex. 20 km SSW of Cocklebiddy, M . D. Crisp s.n., 14 March 1980 ( CBG 8003594 ) .

Affinity:— Daviesia retrorsa clusters weakly with the D. incrassata group ( Fig. 1B ), with which it shares a distinctive calyx and turgid pod; however, the keel is neither sharply incurved nor beaked, and the stamens are strongly dimorphic. Vegetatively it is similar to several species in the genus (see under D. ramosissima ), such as D. brachyphylla , D. ramosissima , D. incrassata subsp. reversifolia and especially D. aphylla . The last taxon has the phyllodes reduced similarly to some plants of D. retrorsa , but differs in having the phyllodes continuous with the branchlets, and in having compressed, thin-walled pods. Also, the flowers of D. benthamii are smaller, e.g. the standard is 5–6 mm broad. All of D. brachyphylla , D. incrassata subsp. reversifolia and D. ramosissima have larger (> 10 mm long), more turgid pods, an incurved beaked keel, and phyllodes fully developed at virtually all nodes, if sometimes small ( D. brachyphylla ). Daviesia incrassata subsp. reversifolia also has phyllodes that are continuous with the branchlets.

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 98. Daviesia retrorsa. A. Flowering branchlet. B. Inflorescence in bud. C. Pod. A, B from Clements 2051 (type); C from Crisp 4859. Drawn by A.L. Prowse. Adapted from Crisp (1995) with permission from CSIRO Publishing.