Daviesia decurrens Meisner (1844: 52)

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

95. Daviesia decurrens Meisner (1844: 52) , Crisp (1987a: 250), Crisp (1995: 1187), Wheeler et al. (2002: 746). Type: ‘In arenosis sylvae prope oppidum Perth, d. 22. Maj. 1839. Herb. Preiss. No. 1147a. (Drummond No. 234).’ Lectotype (Crisp 1995): Preiss 1147 ( LD) ; isolectotypes: BR, FI-W, G (3 sheets) , GOET (2 sheets) , K (2 sheets), MEL (5 sheets), NY (ex Herb. Meisn.), P (2 sheets), S, W (2 sheets). Syntype: Drummond 234 ( BM, ex Herb. Shuttleworth) ; isosyntypes: G (2 sheets) , K (2 sheets) , MEL, OXF, W (2 sheets)

Daviesia prionodes Meisner (1844: 52) . Daviesia pectinata Lindl. var. prionodes (Meisn.) E.Pritz. in Diels & E. Pritzel (1904: 250). Type: ‘ In limoso-calculosis jugi montium Darlings’ -range (Perth) d. 12. September 1839. Herb. Preiss. No. 1148. et in region. interior. Australiae occidentalis, d. 12. Mart. 1840. No. 1141. (Drummond No. 235.)’. Lectotype (Crisp 1995: 1187): Drummond 235 ( BM, ex Herb. Shuttleworth); isolectotype: G (2 sheets) , K (2 sheets) , MEL, OXF, P (2 sheets), W (2 sheets). Syntype: Preiss 1141 ( LD, NY). Syntype: Preiss 1148 ( LD, NY); isosyntypes: G (2 sheets) , MEL .

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Daviesia physodes A.Cunn. ex Don (1832: 125) f. gracilis Meisner (1848: 213) . Type: ‘Swan River, Drummond coll. II. No. 105.’ Holotype: BM (ex Herb. Shuttleworth); isotypes: G (2 sheets), K (3 sheets), LD, MEL, OXF, P, W.

Daviesia hamata Crisp (1995: 1198) . Type: Western Australia, Avon, Quairading , 32°00’S, 117°24’E, M. D. Crisp 6610, 20 July 1980. Holotype: CBG; isotypes: L, NSW, PERTH.

Spreading, erect or occasionally decumbent multi-stemmed shrubs, 0.3–1.8 m high and 0.5–1.5 m broad, glabrous, dull green or rarely glaucous. Root anatomy in both subspecies with anomalous secondary thickening (cord type), sometimes absent or developing late. Branchlets ascending, triquetrous to terete, lightly ribbed or (in subsp. hamata ) striate. Phyllodes scattered, ascending to divaricate, narrowly triangular to subulate, often recurved-falcate, apex acute to acuminate, robustly pungent, vertically compressed or (in subsp. hamata ) terete, inarticulate and decurrent with the branchlet, 2–45 mm long, 1–12 mm broad at the base, lightly ribbed when fresh, conspicuously striate when dry, very rigid in subsp. hamata . Seedling phyllodes leaf-like at the first node, second

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node intermediate and nodes thereafter are adult-like phyllodes; leaf-like phyllodes narrowly obovate, rounded at the apex, with a petiole-like base, not pungent but with a small mucro, 35–40 × 6–8 mm; intermediate phyllodes linearly obovate, acute, becoming pungent, ca. 33 × 2.5 mm; adult-like phyllodes obovate, acute, pungent, becoming falcate, axis turned 90°, 21–26 × 3–3.5 mm. Unit inflorescences 1 per axil, racemose (cluster-like in subsp. hamata ), 3–7-flowered; peduncle 0.5–1.5 mm long; rachis 0–2.5 mm long; barren basal bracts broadly oblong, striate, ca. 1 mm long; subtending bracts spathulate, striate, hooded, ca. 2.5 mm long. Pedicel 0.5–2 mm long. Calyx ventricose, 2–2.5 mm long including the 0.5 mm receptacle which is abruptly constricted to the pedicel, with 5 prominent ribs; upper 2 lobes very small, united higher than the lower 3, ca. 0.25 mm long; lower 3 lobes triangular, 0.5–1 mm long. Corolla : standard transversely elliptic or ovate, emarginate, 5–6 × 6–7 mm including the 1–2 mm claw, with 2 relatively large calli at the base, outer fringe yellow-pink with a large circular velvety red marking at centre; wings obovate, rounded and incurved at the apex to enclose the keel, auriculate, saccate, 4.5–7 × 1.6–2.5 mm including the 1–1.5 mm claw, red; keel half transversely obovate to elliptic, moderately incurved, acute, auriculate, saccate, 4–4.5 × 1.75–2 mm including the 1–1.5 mm claw, red, abaxially rugose. Stamens dimorphic: inner whorl of 5 with slightly longer, narrower filaments and smaller anthers; outer whorl of 5 with shorter filaments and larger anthers; all filaments (except vexillary) strongly compressed and lightly cohering; all anthers (except vexillary) basifixed and 2-celled; vexillary filament broad, channelled, clasping the ovary and style, flared into a pedestal at apex, with confluent thecae. Pod very broadly obtriangular with an acute apex that is sometimes rounded on the upper side, turgid, bluntly beaked, 8–13 × 8–10 mm; upper suture sigmoid; lower suture acute. Seed ovoid, sometimes with a slightly raised radicular lobe, compressed, 4–4.6 mm long, 2.5–2.8 mm broad, 1.5–2 mm thick, dark brown; aril 2.3–3 mm long. ( Figs 95 , 96 ).

Flowering period:— Mainly May to August, though occasionally flowering in October and November. Fruiting period: August to November.

Distribution:— Western Australia, throughout the south-west and eastern margins of the wheatbelt, from near Dongara south to Busselton and east to the Albany area, wih a doubtful outlying record from near Coolgardie.

Affinity:— Daviesia decurrens is similar to D. dilatata , D. pectinata and D. subulata . Daviesia decurrens differs in the fresh state from D. dilatata by the striations and ridges along the phyllodes and branchlets. In particular, the decurrent phyllode-bases make the cross-section of the branchlets sharply triquetrous. When dry, D. dilatata is lightly striate, but neither ridged or ribbed, and the cross-section of the branchlets is bluntly trigonous (immediately below the phyllodes) or terete (lower down). The phyllodes of D. decurrens are not as frequently or strongly decurved as in D. dilatata . Striate bracts further distinguish D. decurrens .

Daviesia pectinata differs in having a much more prominent decurrent rib than D. decurrens . Also, in D. pectinata the bracts are not striate, the raceme-rachis is well developed (2–10 mm long), the calyx is campanulate without prominent ribs and the upper 2 calyx lobes are united into a truncate lip.

Daviesia subulata differs in having phyllodes that are never decurved. Also, in D. subulata the subtending bracts are much smaller (0.5–1 mm long), the calyx lobes are recurved and lack ribs, the standard lacks basal calli and the stamens are strongly dimorphic: the inner whorl of 5 has versatile anthers and confluent thecae.

Daviesia decurrens is closely related to D. intricata , which it resembles in its reproductive morphology, for example in the very small flowers with intense red markings, the rugose keel, the bizarre channelled vexillary filament and the somewhat turgid, bluntly beaked pod. Normally, D. intricata is easily distinguished by its divaricate, straight and very rigid phyllodes; however, plants with short phyllodes resemble D. decurrens subsp. hamata . Typical specimens of D. intricata have much longer phyllodes than subsp. hamata (10–40 mm or more) and the plants are divaricate and intricate due to the numerous spreading branchlets; also, the phyllodes are quite straight and all 5 inner stamens have confluent anthers. A few specimens from localities where these species are sympatric, e.g. around Quairading, appear intermediate (e.g. Crisp 6600, 6609, 6177 and 6178) while others appear typical of either D. intricata subsp. intricata (Crisp 6601) or D. decurrens subsp. hamata (Crisp 6608). This population merits further investigation.

Infra-specific taxa:— Populations in the southern and eastern Darling Range are intermediate between typical D. decurrens (which occurs mainly in jarrah-marri forest on the western side of the Darling Range, and on the coastal plain) and the taxon hitherto known as D. hamata (which occurs in the wheatbelt). Plants in the intermediate populations have upper phyllodes similar in size and shape to those of D. hamata but lower phyllodes larger and compressed as in D. decurrens . These linking populations are sufficiently frequent as to blur the distinction between D. decurrens and D. hamata , and therefore these two taxa are here reduced to subspecies of a single species. Examples are M.D. Crisp 5370 (CBG), V. Crowley DKN 250 and DKN 248 (PERTH), G.J. Keighery & N. Gibson 440 (PERTH), G. Paull 1580 (PERTH) and C.E. Woolcock D29 (CBG).

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Hybrids:— Daviesia decurrens × D. hakeoides . A population on Mt Lesueur, NE of Jurien, Western Australia, appears to comprise segregating hybrids between D. decurrens subsp. decurrens , and D. hakeoides (R.E. Sokolowski 13, 14, 16–20, 22 and 23: CANB, PERTH). Some plants in this population resemble D. decurrens subsp. hamata in their phyllodes, but their bracts are large, as in D. hakeoides .

Figures

FIGURE 95. Daviesia decurrens subsp. decurrens. A–C. Branchlets showing flowers and variation in vegetative morphology. D. Inflorescence. E. Pod. A from Crisp 6655; B from Crisp 6458; C from Crisp 6459; D. from Crisp 6633; E from Koch 2218a. Drawn by B-J. Osborne.

FIGURE 96. Daviesia decurrens subsp. hamata. A. Flowering branchlet. B. Inflorescence. C. Pod. A, B from Crisp 6610 (type); C from Crisp 6181. Drawn by B-J. Osborne. Adapted from Crisp (1995) with permission from CSIRO Publishing.