Daviesia debilior Crisp (1982a: 11)

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

87. Daviesia debilior Crisp (1982a: 11) , ( Crisp 1987a: 249), Crisp (1995: 1185). Type [approximate locality data given because the species is rare]: SW of Eneabba, 30°S, 115°10’E, 19 June 1977, C. Chapman (21 B)77, fl. Holotype: CBG; isotypes: K, PERTH

Shrubs with procumbent stems and many weakly ascending branchlets, to 0.6 m tall and to 1.5 m broad, glabrous, occasionally glaucescent. Root anatomy with anomalous secondary thickening (cord type). Branchlets weakly ascending, angular, prominently ribbed, even when fresh. Phyllodes scattered, reduced to minute scales at upper few nodes or over the entire plant, ascending, angular or compressed, linear, apically acute and mucronate, inarticulate, decurrent and difficult to distinguish from branchlets, 0–120 × 0.4–2 mm, with several prominent ribs. Intermediate phyllodes longer and narrower than juveniles, usually present at base of mature plants. Juvenile phyllodes flat but thick, narrowly spathulate, 20–50 × 4–8 mm, with midrib, thickened margins and many ascending anastomosing raised veins. Stipules minute or absent. Unit inflorescences 1 per axil, modified, condensed racemes, with the lower flowers clustered due to condensation of the rachis, 2–8-flowered; peduncle 1– 2.5 mm long; rachis 0.5–5 mm long; barren basal bracts numerous, forming an involucre, oblong, imbricate, enclosing buds, striate, ca. 1 mm long; subtending bracts spreading, obovate, tridentate, striate, claw fused to pedicel, ca. 3 × 2 mm. Pedicel filiform, 1–5 mm long. Calyx obconical to campanulate, 1.5–3 mm long including the ca. 1 mm receptacle; upper 2 lobes ± united or with a very shallow sinus, 0.5–1 mm long; lower 3 lobes triangular, acute, occasionally slightly recurved, 0.2–0.75 mm long. Corolla : standard transversely broadly elliptic, emarginate, cordate, deeply centrally grooved, 5–6.5 × 6–7 mm including the 1–1.5 mm claw, yellow infused with purple-black or red towards the centre and with a vertical yellow line towards the base in front, deep orange-pink to purple behind; wings obovate with a rounded, incurved apex not enclosing the keel, auriculate, 5–6 × 2–2.5 mm including the 1–1.5 mm claw, orange-pink; keel half transversely elliptic with an acute apex, falcate, slightly

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CRISP ET AL.

auriculate, saccate, 4–5.5 × 2 mm including the 1–3 mm claw, dark purple-red. Stamens dimorphic but only in the anthers; inner whorl of 5 with globose anthers with confluent thecae; outer whorl of 5 with narrowly ovoid 2-celled anthers; all filaments equal, free; all anthers basifixed. Pod obliquely very broadly obtriangular, shortly acuminate, strongly compressed, 14–17 × 9–12 mm; upper suture sigmoid; lower suture acute. Seed compressed, ovoid, 3.5 mm long, 2.5 mm wide, 1.5 mm thick, tan with obscure grey markings; aril thickly lobed, 1.75 mm long. ( Fig. 87 ).

Flowering period:— May to July. Fruiting period: September to November.

Distribution:— Western Australia, from Eneabba south to Darlington (near Perth) and inland to the Wongan Hills.

Habitat:— Grows on gravelly lateritic clay or sandy, sometimes gravelly soils, in heath.

Affinity:— Daviesia debilior belongs to an endemic Western Australian group with numerous moderately enlarged imbricate bracts and frequently leafless branchlets. This group is not to be confused with the Daviesia series Involucratae (Endl.) Benth. , in which the bracts are few, enormous and leaf-like. All but one of the species in the group have a more erect, stronger habit than D. debilior .

A MONOGRAPH OF DAVIESIA

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Daviesia hakeoides is easily recognised by its pungent phyllodes. Specimens of D. hakeoides subsp. subnuda may appear leafless, but they always have some pungent phyllodes at least 2–3 mm long, which is immediately obvious when a finger is run down the branchlet. Daviesia hakeoides also differs from D. debilior in having pods which are beaked because the lower suture is more or less indented near the apex. In D. debilior subsp. debilior (q.v.) there is an abrupt transition from fully developed phyllodes to minute scales part-way up the branchlet ( Fig. 87A ). By contrast, D. hakeoides subsp. hakeoides reduce gradually all the way up the branchlet, this being the typical condition in the genus.

Daviesia gracilis and D. triflora are leafless like D. debilior subsp. sinuans (q.v.), but both differ from it in having larger flowers (standard lamina 6.5–8 mm long, calyx 2.5–3 mm long), differently shaped calyces, and branchlets that are more terete and striate than angular and ribbed.

Daviesia pseudaphylla shares with D. debilior a weak habit, non-pungent phyllodes and a tendency for the phyllodes to reduce abruptly to scales on the upper portion of the branchlets. Daviesia pseudaphylla differs in not having costate branchlets and phyllodes, even when fresh, longer internodes (15 ± 5 mm s.d.), a clear distinction between lamina and claw in the subtending bracts, larger flowers (e.g. standard ca. 10.5 mm broad, calyx 3–3.5 mm long), deep pink colouring with no central streak on the abaxial face of the standard, and a pod with a strong indentation on the adaxial suture.

Daviesia hakeoides subsp. subnuda overlaps in distribution with D. debilior subsp. sinuans and these taxa have been confused. Diagnostic differences are described under the former.

Figures

FIGURE 87. Daviesia debilior subsp. debilior. A. Flowering branchlet. B. Juvenile phyllode. C. Intermediate phyllode. D. Inflorescence. E. Calyx opened out, upper lobes at left. F. Standard. G. Wing. H. Keel. I. Pod. Daviesia debilior subsp. sinuans. J. Fruiting branchlet. K Seed, lateral view. L. Same, hilar view. A from Chapman (21B)77 (type); B–H from Chapman s.n. (CBG 8004030); I from Chapman (66)77; J from Ising s.n. (AD 97622028); K, L from Demarz 1854. Drawn by A.L. Prowse.