Daviesia megacalyx Crisp (1995: 1209)

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

81. Daviesia megacalyx Crisp (1995: 1209) . Type [approximate locality data given because the species is rare]: Western Australia, Eyre, near Ravensthorpe , 33°40’S, 120°10’E, M. D. Crisp 6065, J. Taylor & R. Jackson, 22 September 1979. Holotype: CBG; isotypes: K, PERTH

Shrubs to 1.5 m tall, glabrous. Root anatomy with anomalous secondary thickening (cord type). Branchlets erect, angular. Phyllodes scattered, erect, narrowly obovate or elliptic, apex apiculate, with a small mucro, rarely retuse, tapered to the articulate base, 40–80 × 5–12 mm, with a faint midrib and barely visible venation, coriaceous, green. Unit inflorescences 1 per axil, 1(2)-flowered; peduncle 1–2.5 mm long; rachis 0–2.5 mm long; subtending bracts spreading, oblong, ca. 3 mm long. Pedicels 3–6 mm long, much longer than the stipe-like receptacle. Calyx 3.5–5 mm long in flower including the 1.5 mm receptacle, in fruit enlarged 2-fold and thickened, persistent, black and conspicuous after fruit has fallen; lobes ± uniform, triangular, ca. 2.5 mm long. Corolla : standard very broadly ovate, slightly emarginate, ca. 11 × 12–14 mm including the 2.5 mm claw, apricot towards margins, maroon towards centre, with an intensely yellow central marking; wings broadly spathulate, strongly incurved and rounded at apex but scarcely overlapping, auriculate, ca. 8.5 × 5–5.5 mm including the 2 mm claw, deep pink; keel half elliptic, acuminate, inflated, auriculate, saccate, ca. 6.5 × 2.5 mm including the 2.5 mm claw, deep pink. Stamens strongly dimorphic: inner whorl of 5 with slender, terete filaments and shorter, round anthers with confluent thecae; outer whorl of 5 with broader, compressed filaments and longer, oblong, 2-celled anthers; filaments free. Pod obliquely shallowly obtriangular, acute, compressed, 20–23 × 9–11 mm, pericarp coriaceous; upper suture sigmoid; lower suture strongly acute. Seed obloid, ca. 5 mm long, 3 mm broad, 2 mm thick, light brown with no mottling; aril 2.5 mm long. ( Fig. 81 ).

Flowering period:— August and September. Fruiting period: August to October.

Distribution:— Western Australia, restricted to the Ravensthorpe area.

Habitat:— Gravelly laterite or red clay with ironstone gravel in mallee-heath or dense shrubland, dominated by Eucalyptus preissiana Schauer (1844: 131) , E. pleurocarpa and E. falcata (1847: 163) s.l.

Conservation status:— National: Endangered. WA: Critically Endangered, Declared Rare Flora.

A MONOGRAPH OF DAVIESIA

Phytotaxa 300 (1) © 2017 Magnolia Press • 185 186 • Phytotaxa 300 (1) © 2017 Magnolia Press

CRISP ET AL.

Additional specimens examined:— Approximate locality data are given because the species is rare. WESTERN AUSTRALIA. Eyre: near Ravensthorpe , 33°40’S, 120°10’E, M . D. Crisp 4956, 9 January 1979 ( CBG, MEL, MO, NSW, PERTH); ibid., K . Newbey 569, 21 October 1962 ( PERTH); ibid., A. S . George 5773, 31 August 1963 ( CANB, PERTH); ibid., C. E . & D.T. Woolcock D 254, 18 September 1982 ( CBG); ibid., M . D. Crisp 8986 & W . Keys, 21 October 1996 ( CBG, PERTH) .

Affinity:— The peculiar calyx, for which D. megacalyx is named, sets it apart from all other species in the genus except D. obovata . In both these species the calyx increases to twice its size from flower to fruit, hardening and turning black in the process. After the pods have dehisced and fallen, these old black calyces persist on the plant for a considerable period, giving the appearance of fruits from a distance. Despite this, these two species differ in several characters. Daviesia obovata may be distinguished by its much broader phyllodes (18–45 mm), by its glaucous foliage, by its larger, 2–3-flowered racemes, and by its longer flowering calyx (7–8 mm).

Figures

FIGURE 81. Daviesia megacalyx. A. Fruiting branchlet. B. Inflorescence. C. Pod. A, B from Crisp 6065 (type); C from Newbey 569. Drawn by B-J. Osborne. Adapted from Crisp (1995) with permission from CSIRO Publishing.