Daviesia epiphyllum Meisner (1855: 27)

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

84. Daviesia epiphyllum Meisner (1855: 27) , Bentham (1864: 87, ‘ epiphylla ’), Crisp (1995: 1192). Type: ‘Drumm. Coll. VI. n. 18.’ Holotype: NY (mistakenly annotated ‘?isotypes’ by Crisp); isotypes: BM, CGE, G, K (2 sheets), LD, MEL, OXF, W. Note: The spelling of the epithet used here ( epiphyllum ) is as published originally, which is orthographically correct, meaning ‘upon the leaf’. Presumably, this refers to the insertion of the inflorescences on the lamina of the flattened phylloclade. Grammatically, the epithet is a noun in apposition to the generic name, with which it does not have to agree. Bentham incorrectly altered the spelling to ‘ epiphylla ’ and subsequent authors followed him

190 • Phytotaxa 300 (1) © 2017 Magnolia Press

CRISP ET AL.

Broad shrubs ca. 0.5–1.5 m high, very rigid, glabrous, pruinose. Root anatomy with late-developing anomalous secondary thickening (cord type). Branchlets modified into flattened phylloclades, ca. 5–20 mm broad, with a ‘staghorn’ branching pattern, terminating in robust spines; phylloclade surfaces wrinkled when dry. Phyllodes present on upper phylloclades as oblong-triangular lobes, cuspidate, robustly pungent, 3–12 mm long and 3–8 mm

A MONOGRAPH OF DAVIESIA

Phytotaxa 300 (1) © 2017 Magnolia Press • 191 wide at base; phyllodes reducing to minute (ca. 1 mm) scales on the face and margins of lower phylloclades, narrowly triangular, acute. Unit inflorescences solitary in scale-leaf axils (occasionally in phyllode axils), condensed-racemose, 3–7-flowered; peduncle 1–2 mm long; rachis 2–4 mm long; barren basal bracts numerous, forming an involucre, 1–2 mm long; subtending bracts elliptic, recurved to partially enclose immature pedicel, ca. 5 mm long. Pedicels decurrent with rachis, 4–10 mm long. Calyx 9–10 mm long including the 2–3 mm receptacle; upper 2 lobes united in a truncate lip, ca. 1.5 mm long; lower 3 lobes narrowly triangular, ca. 1.5 mm long. Corolla : standard broadly elliptic, remaining partly folded longitudinally, deeply emarginate, 23–25 × 16–18 mm including the 2–3 mm claw, watery yellow-red with a yellow centre inside and watery red outside; wings narrowly elliptic, apically rounded but neither incurved nor overlapping, deeply auriculate, 23–29 × 4.5–5.5 mm including the ca. 3 mm claw, watery red; keel half transversely ovate, acute, auriculate, 24–26 × 5–6 mm including the 2–3 mm claw, watery red. Stamens strongly dimorphic: inner whorl of 5 with much longer, slender, terete filaments and round, versatile anthers with confluent thecae that are ca. half the size of the outer anthers; outer whorl of 5 with much shorter, broader, compressed filaments thickened at the base and longer, 2-celled, basifixed anthers; filaments free. Pod obliquely shallowly obtriangular, acuminate, compressed, 25–35 × 14–17 mm; upper suture sigmoid; lower suture acute. Seed 3–4 mm long, 2.2–3 mm wide, 1–1.5 mm thick; aril ca. 2 mm long. ( Fig. 84 ).

Common name:— Staghorn Bush.

Flowering period:— April to June. Fruiting period: June to September.

Distribution:— Western Australia, sandplains north of Perth from 50 km N of Bullsbrook to Eneabba and inland as far as the Moora vicinity.

Habitat:— Grows in sand or gravelly sand on sandplains in heathland often dominated by Eucalyptus pleurocarpa s.l. or E. macrocarpa Hooker (1841 : t. 405).

Selected specimens (21 examined):— WESTERN AUSTRALIA. Irwin: 2 km E of the Brand Highway on the Coorow – Green Head road, 30°06’S, 115°20’E, C . Chapman (67)77, 25 August 1977 ( CBG); 88.7 km from Three Springs , 29°53’S, 115°13’E, C . Chapman (26 B)77, 19 June 1977 ( CBG, MEL); W of Dinner Hill , 30°20’S, 115°36’E, A . S . George 2345, 25 April 1961 ( PERTH); Mt Peron , 30°07’S, 115°09’E, C . A . Gardner 9400, 26 August 1949 ( PERTH) .

Affinity:— This species is difficult to confuse with any other in the genus because of the distinctive cladodes and large flowers. Nevertheless, both the molecular phylogeny (clade VII.d, Fig. 1B ) and morphological synapomorphies show clearly that D. speciosa is the sister species of D. epiphyllum . Unique characters shared by these species include nearly identical red bird-pollinated flowers that are much larger than any others in the genus, as well as the vegetative habit, in which plants have a non-reproductive ‘crown of thorns’ with terminating growth. Inflorescences and new shoots emerge lower on the stems, from nodes subtended by scale-leaves. However, these species are easily distinguished by the terete branchlets and phyllodes of D. speciosa versus the broad, flat phylloclades of D. epiphyllum .

Note on morphology:— The terminal vegetative lobes of D. epiphyllum are so broadly decurrent and continuous with the phylloclades as to be nearly indistinguishable from them. Nevertheless, we have interpreted these lobes as phyllodes, partly because they are positionally equivalent, and thus likely homologous, to the fully developed phyllodes of D. speciosa . Moreover, like the terete phyllodes of D. speciosa , they lack nodes or subtending scale-leaves and are replaced by scale-leaves lower on the stems. Moreover, the occasional presence of an inflorescence in the axil of a near-terminal spine of D. speciosa , and of a lobe in D. epiphyllum , supports the phyllode hypothesis for these structures. To resolve the homology of these structures in the two species will require detailed anatomical and developmental analysis.

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 84. Daviesia epiphyllum. A. Flowering branchlet. B. Inflorescence. C. Pod. A from Chapman (26B)77; B from Chapman (4), 27 Apr. 1979; C from Gardner 9400. Drawn by A.L. Prowse.