Daviesia pteroclada Crisp (1995: 1223)

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

93. Daviesia pteroclada Crisp (1995: 1223) . Type [approximate locality data given because the species is rare]: Western Australia, Irwin, near Green Head , 30°’S, 115°30’E, C. Chapman s.n., 1 August 1978. Holotype: CBG 9408372 ; isotypes: K, L, MEL, NSW, PERTH

Broom-like leafless shrubs, to 1.8 m tall, glabrous, glaucescent. Root anatomy normal (unistelar) or with anomalous secondary thickening (cord type). Branchlets erect or ascending, modified to cladodes, narrowly winged, compressed or triquetrous, 1.5–3.5(–8) mm broad, striate between the sharp ridges, even when fresh. Phyllodes reduced to scales in the adult plant. Seedling phyllodes at first narrowly obovate and horizontally flattened (nodes 1–4), becoming vertically compressed and subulate (nodes 6–8), reduced to scales thereafter. Unit inflorescences 1 per axil, racemes with the lower flowers clustered due to condensation of the rachis, 2–4-flowered; peduncle up to 1 mm long; rachis 0.5–2 mm long and concealed by the imbricate basal barren bracts; subtending bracts spreading, spathulate, abruptly contracted to the petiole-like base, with margins incurved, faintly striate, fused at the base of the pedicel, ca. 5 mm long. Pedicels thickening towards the apex, 2.5–3.5 mm long. Calyx 2– 2.5 mm long including the ca. 0.5 mm receptacle; upper 2 lobes united in a truncate, emarginate lip, ca. 0.75 m long; lower 3 lobes triangular, acuminate, ca. 0.25 mm long. Corolla ; standard transversely broadly elliptic, emarginate, 6.5–8 × 7–8 mm including the ca. 1 mm claw, deeply channelled near the base, orange at margins and grading through to dark red (or dark grey) towards centre, with blackish veins, lacking a central yellow mark, fading with age to yellow and light grey; wings spathulate, abaxial margins divergent, apically incurved and scarcely overlapping the keel, auriculate, 4.5–5 × 2–2.5 including the ca. 1 mm claw, dark grey grading to red at tips and margins; keel half transversely broadly elliptic, acute, abaxially rugose, auriculate, saccate, 3.5–4 × 1.75–2 mm including the 1–1.5 mm claw, dark red. Stamens strongly dimorphic: inner whorl of 5 with longer, filiform

A MONOGRAPH OF DAVIESIA

Phytotaxa 300 (1) © 2017 Magnolia Press • 209 filaments and shorter, versatile, anthers with confluent thecae; outer whorl of 5 with shorter, compressed filaments and longer, basifixed, 2-celled anthers; filaments free. Pod obliquely shallowly obtriangular, acute, compressed, 10–12 × 7–8 mm, rather thin-walled; upper suture sigmoid; lower suture acute. Seed ellipsoid, 3.6–4.7 mm long, ca. 2.5 mm broad, ca. 1.5 mm thick, light to dark brown with black mottling; aril 1.5–2.5 mm long. ( Fig. 93 ).

210 • Phytotaxa 300 (1) © 2017 Magnolia Press

CRISP ET AL.

Flowering period:— July and August (January). Fruiting period: August to October.

Distribution:— Western Australia, from near Eneabba south towards Mt Lesueur.

Habitat:— Grows in sandy clay to sandy loam in woodland-heath with Eucalyptus wandoo .

Conservation status:— National: Not listed. WA: Priority 3, possibly threatened or near-threatened but not yet adequately surveyed.

Selected specimens (12 examined):— Approximate locality data given because the species is rare. WESTERN AUSTRALIA. Irwin: E of Mt Peron , 30°10’S, 115°20’E, C. A . Gardner 9429 per F. A . Grigson, 26 August 1949 ( PERTH); between Green Head and Eneabba , 30°S, 115°10’E, M . D. Crisp 5430, 24 January 1979, flowering adult ( CBG, PERTH); ibid., Crisp 5431, 24 January 1979, seedling ( CBG, PERTH); ibid., D. Kitchener 65, 27 October 1973 ( PERTH); ibid., C . Chapman (35)76, 3 August 1976 ( AD, CBG, K, MEL, MO, NSW, PERTH, UWA) .

Affinity:— The only other species in the genus with phyllodes reduced to scales and narrowly winged, triquetrous cladodes, is D. alata . However, this species is not closely related to D. pteroclada and differs in floral and fruiting morphology; for example the bracts and calyx-lobes are conspicuously fimbriate, and the peduncle is up to 3.5 mm long. Also, D. alata has a procumbent to prostrate habit.

Instead, D. pteroclada is closely related to D. hakeoides ( Fig. 1B ) within a group of species with moderately enlarged, shell-shaped, usually striate bracts which are imbricate and cover the rachis ( Crisp 1982a; 1984). From all members of this group it is immediately distinguished by its leafless, triquetrous branchlets. Daviesia debilior , D. gracilis and D. triflora are at least partly leafless but their branchlets are terete.

Figures

FIGURE 1A. Phylogeny (part) of Daviesia estimated using maximum likelihood (PHYML) from concatenated sequences of ITS (nrDNA), and ndhF and trnL–trnF (cpDNA). The tree was rooted using the monotypic sister groups Viminaria and Erichsenia (not shown). The informal clade names are used for reference in the taxonomic treatment. Numbers on branches show non-bootstrap support. The tips are labelled with the taxon name and sample accession number.

FIGURE 93. Daviesia pteroclada. A. Flowering branchlet. B. Inflorescence. C. Pod. A from Crisp 5430; B from Chapman s.n. (CBG 7805042); C from Gardner 9429. Drawn by B-J. Osborne. Adapted from Crisp (1995) with permission from CSIRO Publishing.