Daviesia rhizomata Crisp (1995: 1230)

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

131. Daviesia rhizomata Crisp (1995: 1230) . Type: Western Australia, Roe , 26 km NNE of Hyden, 32°13’S, 118°55’E, M. D. Crisp 5558, 29 January 1979. Holotype: CBG; isotypes: K, NSW, PERTH

Low shrubs with numerous stems in tufts arising from enlarged rootstocks (lignotubers) from which strongly differentiated rhizomes spread to establish new plants, glabrous, glaucescent to bluish. Root anatomy with anomalous secondary thickening (cord type). Branchlets ± erect, flexuose, smooth when fresh, striate when dry. Phyllodes scattered, widely spreading or slightly retrorse, terete, apex often slightly recurved, acicular, pungent, inarticulate, 4–45 mm long, 1–2 mm diam., smooth when fresh, striate when dry. Unit inflorescences 1 per axil, 1- flowered; peduncle 1–2 mm long; rachis nil; barren basal bracts very small, forming an involucre, ca. 0.25 mm

A MONOGRAPH OF DAVIESIA

Phytotaxa 300 (1) © 2017 Magnolia Press • 285 long; subtending bracts ascending, oblong, ca. 0.75 mm long. Pedicels geniculate, 1–3 mm long. Flowers gaping as the keel deflexes to expose the stamens. Calyx narrowly campanulate, 4–5 mm long including the ca. 1 mm stipitate receptacle; lobes acuminate, upper 2 united higher than the lower 3, ca. 1.75 mm long. Corolla : standard very broadly ovate, slightly reflexed with incurved margins, emarginate, callose, ca. 7 × 7–9 mm including the 1.5 mm claw, with 2 small calli at the base of the lamina, yellow with red infusion at the base and an intensely yellow vertical central streak; wings narrowly obovate, slightly lobed on abaxial margin towards apex, apically incurved, auriculate, ca. 7 × 2.5 mm including the 1.5 mm claw, red with yellow tips; keel half elliptic, deflexed to expose the stamens, acute, with adaxial margins involute, ca. 8 × 2 mm including the 2.5 mm claw, red and yellow. Stamens weakly dimorphic: inner whorl of 5 with subdorsifixed, smaller anthers; outer whorl of 5 with basifixed, longer anthers; filaments uniform in length, all compressed and cohering; anthers all 2-celled. Pod obliquely shallowly obtriangular, acute, somewhat turgid, 11–13 × 6–7 mm; upper suture slightly sigmoid; lower suture ca. 90° to scarcely obtuse. Seed not seen. ( Fig. 132 ).

Flowering period:— January and February. Fruiting period: Unknown.

Distribution:— Western Australia, centred on Hyden and extending west towards Kulin, east into unoccupied mallee country and south to the Lake Grace–Newdegate area.

Habitat:— Grows in gravelly sandy laterite or sand over laterite on flat areas in diverse tall heath including Acacia , Allocasuarina campestris , Banksia , Gastrolobium , Grevillea , Leptospermum and Melaleuca .

Additional specimens examined:— WESTERN AUSTRALIA. Roe: 16 km SE of Kulin , 32°43’S, 118°16’E, R . Hnatiuk 780044, 12 January 1978 ( PERTH); ca. 55 km E of Hyden, 3 km NE of Marble Rocks , 32°30’S, 119°26’E, M . D. Crisp 5552, 29 January 1979 ( CBG, PERTH); ca. 50 km NE of Lake Grace, 16 km E of Pingaring , 32°45’S, 118°48’E, M . D. Crisp 5543, 28 January 1979 ( AD, CBG, L, MEL, MO, PERTH); 33 km E of Pingaring along road to Varley , 32°44’S, 118°57’E, M . D. Crisp 5546, 29 January 1979 ( AD, CBG, PERTH); 6.4 km W along Jilakin Flat Rocks Road from Holt Rock South Road , 2 km W of S tip of Lake Varley , 32°42’S, 119°20’E, M . D. Crisp 9002, 22 October 1996 ( CBG) .

Affinity:— Superficially there seems little to distinguish D. rhizomata from the many species of Daviesia with terete, pungent phyllodes. However, this species has some distinctive diagnostic characters, especially the rhizomes. While rhizomes are not unique to this species, they appear more developed than in other Daviesia species. They are produced so freely that in the field the plants form networks of interconnected tufts and clumps. Daviesia scabrella is vegetatively similar with a low, spreading rhizomatous or stoloniferous growth habit but the phyllodes are green (not bluish) and have a minutely scabrid epidermis; also, the floral morphology differs, e.g. the margins of the standard are recurved and the central yellow mark is shaped like a starburst.

Daviesia rhizomata is quite similar to D. uncinata , and though the distributions of these species partially overlap, there is no sign of intergradation. Daviesia uncinata may be distinguished by the tufted, non-rhizomatous growth habit, usually ascending uncinate phyllodes, 2-several-flowered racemes, smaller flowers (standard 4–5 mm broad; calyx 2.5–3 mm long) and the uncinate, acicular-beaked keel.

Figures

FIGURE 132. Daviesia rhizomata. A. Rhizome terminating in an aerial branchlet. B. Root crown with a lignotuber. C. Flowering branchlet. D. Inflorescence (1-flowered). E. Pod. A, B from Crisp 5558 (type). C–E from Crisp 5543. Drawn by A.L. Prowse. Adapted from Crisp (1995) with permission from CSIRO Publishing.