Daviesia pachyloma Turczaninow (1853: 263

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

2. Daviesia pachyloma Turczaninow (1853: 263 , ‘ pachylima ’), Bentham (1864: 85, ‘ pachylina ’), Crisp (1995: 1220). Type: ‘Drum. V. n. 43. Specimen imperfectum Gilbertianum, sub. n. 252, foliis angustioribus gaudens, verosimiliter huc etiam spectat.’ Lectotype (Crisp 1995: 1220): Drummond coll. V. no. 43 (KW); isolectotype: BM (2 sheets), CGE, G, K (3 sheets), MEL, P, W. Syntype: Western Australia, Gilbert 252, 1842 (KW). Note: The published

A MONOGRAPH OF DAVIESIA

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CRISP ET AL.

spelling of the epithet (‘ pachylima ’) was a transcription error from the original spelling ‘ pachyloma ’ as seen in Turczaninov’s handwriting on the lectotype. Whereas the spelling ‘ pachyloma ’ (meaning thick-margined) was clearly intended to refer to the phyllodes, the published version ‘ pachylima ’ is etymologically unintelligible. Perhaps this is why Bentham (1864: 85) altered the spelling to ‘ pachylina ’ (meaning ‘thick line’, but with no apparent allusion to any part of the plant) Bushy, spreading shrubs with rigid, zigzagging branches to 0.5 m high, mostly glabrous but branchlets occasionally scabrous. Root anatomy with anomalous secondary thickening (cord type). Branchlets terete, ribbed, compressed to flattened vertically. Phyllodes scattered, ascending, very narrowly elliptic to linear, apically acuminate and pungent, basally articulate, with thickened margins, 8–65 × 1–2 mm, wrinkled when dry; stipules conspicuous, pungent. Inflorescence: flowers solitary in axils of uppermost 1–5 leaves or bracts, thus comprising undifferentiated racemes terminating main or lateral shoots; peduncle 0–2.5 mm long, glabrous to scabrous; rachis 0–1.5 mm long, glabrous to scabrous; subtending bracts oblong, keeled, 0.7–1.5 mm long, glabrous to scabrous. Pedicel 1–4 mm long. Calyx 5–6 mm long including the 1.5–2 mm receptacle; lobes triangular, 2–3 mm long; upper 2 lobes united higher and closer together than the lower 3. Corolla : standard ovate to very broadly ovate, emarginate, 6–10 × 6–7.5 mm including the 1–2 mm claw, with 2 very small calli at the base of the lamina, yellow with a triangular red border, and fine red veins radiating outward, around the yellow centre; wings oblong with a rounded to truncate apex, auriculate, 6–8 × 1.5–2.5 mm including the ca. 1.5 mm claw, yellow; keel half transversely elliptic (canoe-shaped), acute, auriculate, slighty saccate, 7–7.5 × 2–3.5 mm including the ca. 2 mm claw, pale creamy yellow. Stamens weakly dimorphic: inner whorl of 5 with slender, slightly shorter, versatile anthers; outer whorl of 5 with oblong, longer, basifixed anthers; filaments free, ca. uniform, broad and flattened, tapering towards the apex; anthers all 2-celled. Pod obliquely shallowly obtriangular, acute, with a long, persistent style, compressed, ca. 8 × 3.5 mm; upper suture sigmoid; lower suture obtuse. Seed irregularly ellipsoid, 2.8–3.1 mm long, ca. 2 mm broad, 1.2–1.4 mm thick, lightly cream-coloured with some black mottling; aril ca. 1.7 mm long. ( Fig. 3 ).

Flowering period:— March to January. Fruiting period: January to March.

Distribution:— Western Australia, scattered sparsely across the wheatbelt and semi-arid woodlands from Manmanning east to Zanthus and south to the latitude of Kulin and Holt Rock.

Habitat:— Grows in red or white, sometimes clayey, sand in mallee, often with Triodia Brown (1810a: 182) .

Selected specimens (30 examined):— WESTERN AUSTRALIA. Avon: 1 km SW of Manmanning , 30°52’S, 117°05’E, B. H . Smith s.n., 17 March 1980 ( CBG 8002069 ). Coolgardie: Warangering [Wargangering Rock], 31°11’S, 120°31’E, R . Helms 1, 14 November 1891 ( AD, CANB, NSW). Roe: 43 km E of Hyden, on Norseman road, 32°25’S, 119°19’E, A. S . George 6061, 1 January 1964 ( CANB, PERTH); 29 km E of Lake Grace towards Newdegate , 33°06’S, 118°48’E, M . D. Tindale 203 & B. R . Maslin, 20 March 1970 ( CANB, NSW, PERTH) .

Affinity:— Within the genus, only D. anceps shares with D. pachlyloma an undifferentiated inflorescence, consisting of solitary flowers in the axils of the uppermost phyllodes or bracts at the tips of shoots. All other species have a differentiated unit inflorescence in the axil of a phyllode (or scale leaf), subtended by a cluster of involucral bracts at the base of a peduncle, with more barren bracts along the peduncle. Even in species with solitary flowers (e.g. D. uniflora and D. ulicifolia ), the differentiated inflorescence structure is evident. Daviesia anceps differs from D. pachyloma in having scale leaves and flattened linear phylloclades. Other species of Daviesia lack the combination of linear-elliptic phyllodes with thickened margins and conspicuous, pungent stipules seen in D. pachyloma . Daviesia reclinata has a relatively undifferentiated inflorescence (long axillary racemes and terminal panicles), though there is a peduncle with barren bracts, as in most species of the genus. This species occurs in the monsoonal tropics (Arnhem Land and the Kimberley) and differs from D. pachyloma in having linear phyllodes 10–150 mm long and an accrescent calyx.

II. D. microcarpa Clade

Figures

FIGURE 3. Daviesia pachyloma. A. Flowering branchlet. B. Phyllode and terminal raceme. C. Pod. A, B from George 6061; C from Smith s.n. (CBG 8002069). Drawn by A.L. Prowse.