Levenhookia pusilla R.Br., Prodr. Fl. Nov. Holland. 573. 1810

Wege, Juliet A., 2020, Styleworts under the microscope: a taxonomic account of Levenhookia (Stylidiaceae), PhytoKeys 151, pp. 1-47 : 1

1. Levenhookia pusilla R.Br., Prodr. Fl. Nov. Holland. 573. 1810 Figs 1C , 3B

Leeuwenhoekia pusilla , orth. var.: A.P. De Candolle, Prodr. 7: 338. 1839.

Leeuwenhookia pusilla , orth. var.: O.W. Sonder in J.G.C. Lehmann, Pl. Preiss. 1(3): 392. 1845.

Leewenhoekia pusilla , orth. var.: F. von Mueller, Syst. Census Austral. Pl.: 86. 1882.

Type.

Australia. Western Australia: near the observatory, Princess Royal Harbour, King George’s Sound, 21 Dec 1801, R. Brown s.n. [Bennett No. 2613] (lectotype, designated by Wege (2017: 231): BM 001041273; isolectotype: BM 000948765).

Description.

Annual herb 1-10 cm high. Glandular hairs ca. 0.1-0.2 mm long. Stem dark red, simple or branched to varying degrees with porrect lateral branches, mostly glabrous, a few glandular hairs sometimes present distally on the lateral branches. Leaves cauline, scattered, green adaxially, dark red or purplish red abaxially; lamina oblanceolate to narrowly oblanceolate, reniform, ovate or elliptic, 1.5-15 mm long including the petiole, 1-6.5 mm wide, obtuse or subacute, glabrous or scarcely papillate. Flowers in corymbs, usually crowded amongst the bracts, 1-500+ per plant; bracts narrowly oblanceolate to oblanceolate or linear, 1.8-9 mm long, usually glabrous, sometimes scarcely papillate on the margins, the upper-most bracts sometimes with a few glandular hairs abaxially towards the base; pedicels 0.3-2.5 mm long, sparsely glandular-hairy. Hypanthium globose, ellipsoid or ovoid, 0.7-1 mm long, 0.6-0.9 mm wide, with glandular hairs throughout and eglandular hairs 0.2-0.6 mm long distally. Calyx lobes subequal (with the anterior pair scarcely longer than the rest), 1-1.7 mm long, acute or subacute, glabrous or sparsely glandular-hairy towards the base, sometimes scarcely papillate apically. Corolla pink with a white base or occasionally all white, glabrous; lobes evenly arranged or sometimes ± paired vertically, distally recurved, obovate, ± equal in size or with the anterior pair scarcely longer than the posterior ones, 0.9-1.5 mm long, 0.6-0.9 mm wide, rounded or scarcely apiculate; tube white, 0.3-0.6 mm long, shorter than the calyx lobes. Labellum dorsal or sometimes ventral (rarely lateral), 0.7-0.8 mm long including a 0.1-0.2 mm long claw; hood dark red-pink or red-purple, usually sparsely glandular-hairy abaxially, minutely papillate adaxially along the margins; appendage at the cleft apex red-pink, ca. 0.1-0.2 mm long, papillate; basal appendages white, linear-subulate, ca. 0.3 mm long. Column sheath creamy white, glabrous, irregularly lobed, to 0.3 mm high, pendulous appendages absent. Column white, often tipped red-pink, free, 1-1.5 mm long, distally broadened and angled toward labellum, glabrous; stigmatic lobes to 0.4 mm long, developing while the column is hooded, erect to incurved. Capsule ovoid, 1.3-3 mm long excluding calyx lobes. Seeds 0.4-0.7 mm long, 0.3-0.4 mm wide.

Diagnostic features.

Levenhookia pusilla has a dark red and glabrous primary stem axis, glabrous or scarcely papillate leaves and outermost bracts that are usually green adaxially and dark red or purplish red abaxially, and tiny flowers with a pink and white (occasionally all white) corolla with lobes 1-1.5 mm × <1 mm.

Phenology.

Flowering from mid-September to early December; fruiting from October to early January.

Distribution.

Levenhookia pusilla has a disjunct distribution in southern Australia (Fig. 3A ). In south-western Australia, it is common in the Jarrah Forest, Warren and Swan Coastal Plain bioregions and scattered across the southern Avon Wheatbelt, Mallee and Esperance bioregions, with one outlying record from the Geraldton Sandplains. In south-eastern Australia, it is restricted to the Flinders Lofty Block, Eyre York Block, Murray Darling Depression, Naracoote Coastal Plain and Kanmantoo bioregions in south-eastern South Australia, extending into Victoria at Little Desert National Park near the South Australian border.

Habitat.

This species grows in sand or loamy sand on ridges, hill-slopes, plains or dune swales, often with lateritic gravel or in association with granite outcropping; it is more rarely recorded growing in clay or clay loam in depressions or seasonally-wet flats. Associated vegetation is varied and includes tall Eucalyptus woodland or forest, low open woodland with Eucalyptus , Allocasuarina or Melaleuca , shrubland or scrub with Banksia , Melaleuca or emergent mallees, and low heath. It commonly co-occurs with L. stipitata in Western Australia and is often abundant on firebreaks and along track edges.

Conservation status.

Levenhookia pusilla is widespread and locally abundant across most of its range ( IUCN (2012): Least Concern), but it is listed as Vulnerable in Victoria ( Department of Environment and Primary Industries, Victoria 2014), where it is restricted to Little Desert National Park.

Etymology.

From the Latin pusillus (very small); an aptly named plant given its tiny flowers and diminutive habit.

Vernacular name.

Midget Stylewort ( Erickson 1958).

Notes.

Levenhookia pusilla is morphologically allied to L. murfetii (refer to the comparative notes under that species) and the two species are known to grow near one another in Western Australia’s Avon Wheatbelt. It often has a dorsally positioned labellum, a feature shared with L. murfetii and achieved through rotation of the pedicel; however, a ventral or lateral labellum has also been observed in instances where the crowded flowers and bracts prevent rotation or full rotation of the pedicels.

A specimen of L. pusilla from the Geraldton Sandplains bioregion near Warradarge (M. Hislop 1492, PERTH) is a northern outlier: further collections and observations from this region would be of interest, particularly given the widespread occurrence of L. murfetii in this area.

A subset of individuals on the following three specimens of L. pusilla , which are from three separate locations in South Australia, have been infected by a smut: R. Bates 51370 (AD), A.G. Spooner 1619 (AD) and D.J.E Whibley 10106 (AD). A smut has also been detected on collections of L. sonderi (refer to the notes under that species). No smuts have been formally identified on Stylidiaceae to date ( Shivas et al. 2014).

Illustrations.

F. Bauer, Ill. Fl. Novae Holl., t. 15. 1816 [corolla lobes inaccurately depicted]; R. Erickson, Triggerplants 201, Pl. 57, No. 1. 1958; B.J. Grieve & W.E. Blackall, How to know W. Austral. wildfl. 4: 765, No. 3. 1982; H.R. Toelken in J.P. Jessop & H.R. Toelken, Fl. South Austral. 1419, fig. 639b. 1986; E.J. Raulings in N.G. Walsh & T.J. Entwisle, Fl. Victoria 4: 583, fig. 111a. 1999 [the only cited illustration to correctly depict the presence of both eglandular and glandular hairs on the hypanthium]; J. Wheeler, N. Marchant & M. Lewington, Fl. South West 2: 902. 2002.

Selected specimens examined.

Australia. Western Australia: Mt Merivale, 20 km E of Esperance, 29 Nov 1997, B. Archer 911 (MEL); Brixton Street Wetlands, Kenwick, 10 Oct 2007, K.L. Brown & G. Paczkowska KLB 673 (PERTH); Tutanning Reserve, SE of Pingelly, 7 Oct 1973, A.S. George 11712 (PERTH); Julimar forest, corner West Boundary Rd and 7 Mile Rd, 1 Oct 2001, M. Hislop 2319 (PERTH); Bramley National Park, NW Margaret River, off Burnside Rd, 19 Nov 2008, G.J. Keighery 17437 (PERTH); Mira Flores Ave, off Millinup Rd, near Porongurup Range, ca. 3 km W of Porongurup, 31 Oct 1995, T.R. Lally 821 (PERTH); Torbay Hill, West Cape Howe National Park, 16 Nov 1995, T.R. Lally & B.J. Lepschi 913 (PERTH); 50 m N on track off Quartz Rd, ca. 400 m from Coronation Rd, W of Manjimup, 9 Nov 2002, J.A. Wege 795 (PERTH); Near inlet campsite, Waychinicup National Park, 28 Oct 2003, J.A. Wege 1051 & C. Wilkins (PERTH); Margaret River Rd, E of Great N Rd, E of Margaret River, 8 Nov 2009, J.A. Wege 1749 & W.S. Armbruster (K, MEL, PERTH); 1.1 km W of Stan Rd on Blue Lake Rd, SW of Mt Barker, 24 Oct 2018, J.A. Wege 2072 & C. Wilkins (MEL, PERTH); South Australia: Noolook Forest Reserve, 15 Oct 1984, N.N. Donner 10273 (AD, MEL); Myponga Conservation Park, 14 Oct 1986, D.E. Murfet 228 (AD); Newland Head Conservation Park, 29 Sep 2009, D.E. Murfet 6603 (AD); Cox Scrub Conservation Park, 27 Sep 2008, K.A. Shepherd & J.A. Wege KAS 1139 (PERTH); Victoria: Little Desert, 11 Oct 1989, J.G. Eichler s.n. (MEL).

Figures

Figure 1. Levenhookia is a genus of annual herbs endemic to Australia A distribution in temperate and semi-arid regions of Australia, scale bar 1000 km B L. leptantha (J. A. Wege 2063) C L. pusilla (J. A. Wege 1749 & W. S. Armbruster) D L. octomaculata (J. A. Wege 2074) E L. pulcherrima (J. A. Wege 1937). Photos by J. A. Wege.

Figure 3. Comparative distributions and floral morphologies A, B Levenhookia pusilla, with a disjunct distribution in Western Australia and South Australia and a dense inflorescence of pint-sized flowers (unvouchered, Mt Clarence, Albany, Western Australia) C, D L. murfetii, a Western Australian endemic with discrete markings at the base of the corolla lobes (J. A. Wege 1829) E, F L. sonderi, a rarity from South Australia and Victoria with red-purple markings on the labellum that are especially prominent in pressed material (unvouchered, from near St Andrews, Victoria). Photos by J. A. Wege (B), K. R. Thiele (D) and C. Lindorff (F). Scale bar on maps 1000 km.