Common name: Yalwal Wattle
Acacia yalwalensis Kodela APNI*
Description: Erect, straggly or bushy shrub or tree commonly to 9 m or more high (sometimes reaching 20 m high), often with pendulous branches; bark smooth or slightly fissured, grey-brown or green; branchlets terete, slightly angled or flattened towards apices, often pruinose, pilose with fine white-translucent hairs especially on ridges.
Leaves with petiole to 0.7 cm long (sometimes obscured by basal pinnae arising from near pulvinus), mostly with a raised, circular to broadly elliptic or slightly obovate gland at base of or near lowest pair of pinnae; rachis (2.5–) 5–12 cm long, grooved above (a shallow, longitudinal groove flanked on either side by a narrow ridge, or appearing like a broad ridge with a shallow groove running down middle), pilose mostly above (with hairs mainly on the ridges either side of groove and on sides of rachis) but sometimes on both sides, with a jugary or ± jugary gland similar to the petiolar gland occurring mostly at the uppermost 1–4 pairs of pinnae (these glands sometimes occur just below to half-way down, appearing interjugary; glands are sometimes present between the uppermost 9 pairs of pinnae, often irregularly so); pinnae (6–) 10–22 (–29) pairs, (1–) 2–4 (–4.7) cm long, lowermost pair often slightly shorter than others; pinnules dark green above, paler green beneath, (12–) 20–45 (–51) pairs, oblong to narrowly oblong, (1–) 1.5–2.5 (–3) mm long (rarely to 3.5 mm long), 0.5–0.7 (–0.9) mm wide, ciliate often with pilose hairs (sometimes sparsely so), apex obtuse or acute.
Inflorescences in terminal and axillary racemes and panicles. Peduncles (1–) 2–5 mm long, glabrous. Heads globose, c. 9–13-flowered, c. 3–5 mm diam. (when dry), pale yellow or cream-coloured. Flowers 5-merous; calyx cupular, 0.5–0.7 mm long, dissected to c. ¼ its length, glabrous or with whitish hairs in upper parts, near apex and/or along keels; corolla c. 1.2–1.3 mm long, dissected to ½ or splitting further, glabrous or sometimes petals with obscure, minute hairs near their acute apex; ovary glabrous.
Pods straight to curved, ± submoniliform (margins usually slightly to moderately, ± regularly to irregularly constricted between seeds), ± flat but discernibly raised over seeds, 2–8.5 cm long, 4–6.5 mm wide, coriaceous, brownish black or blue-black, usually ± pruinose, with few, fine lateral veins, glabrous; seeds longitudinal, to c. 4.5 mm long; funicle filiform.
Flowering: chiefly June–August; fruiting: September–January.
Distribution and occurrence: mainly known from Danjera Creek/Yalwal Creek catchment and nearby, including the Bundundah Creek valley, around the old gold mining area east of Danjera Dam, and the site of the former settlement of Yalwal. Cultivated records from Nowra.
Grows in clayey soils and sandy loams, on hill slopes, creek banks and roadsides, commonly with Eucalyptus beyeriana, E. punctata, E. ralla, E. tereticornis, Angophora floribunda, Acacia filicifolia, A. mearnsii, Bursaria spinosa and Olearia viscidula. In a sheltered forest in Sawpit Gully it also grows with rainforest species (K. Mills pers. comm.).
NSW subdivisions: SC
Previously confounded with Acacia oshanesii F.Muell. and recognised as a southern variant with narrow pods and ciliate pinnules. Hybridises with Acacia baileyana. Named after the former gold mining settlement of Yalwal. See also Kodela (2015).
Text by P.G. Kodela, January 2015
Taxon concept: P.G. Kodela, Telopea 18: 27-31 (2015)
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