Lepidium naufragorum Garn.-Jones et D.A.Norton, New Zealand J. Bot. 33, 43 (1995)

Lange, P. J. de, Heenan, P. B., Houliston, G. J., Rolfe, J. R. & Mitchell, A. D., 2013, New Lepidium (Brassicaceae) from New Zealand, PhytoKeys 24, pp. 1-147 : 55-59

Lepidium naufragorum Garn.-Jones et D.A.Norton, New Zealand J. Bot. 33, 43 (1995)

Holotype.

New Zealand: Open Bay Islands, Taumaka, 15 February 1992, P. J. Garnock-Jones 2121, D. A. Norton & D. R. Given, CHR 470212!

Etymology.

The epithet ' naufragorum ', the genitive plural form of ' naufragus ' meaning a 'castaway or ship wrecked person’, was given by Garnock-Jones and Norton (1995) to commemorate a sealing gang that was set down on the type locality of the species, the Open Bay Islands, in 1810 where they were left for four years until they were rescued.

Description

( Figs 55 , 56 ). Tap-rooted, pungent-smelling, summer-green, perennial herb forming a densely leafy, shrub up to 680 mm tall, rootstock stout, 3-10 mm diam. when fresh semi-circular, whitish-grey (when exposed). Tap root fleshy, yellow to yellow-white when fresh, up to 300 mm long, deeply descending. Plants dying down in winter or in times of adversity to rootstock. Stems ascending to erect, 150-680 mm long, glabrous, 2-8 mm diam., woody near base, prominently ridged and/or grooved with age, and usually bearing numerous leaf scars and withered petioles, pale yellow-green to dark green, sometimes tinged maroon; mid to upper portion of stems much branched; branches and branchlets, usually very leafy. Leaves glabrous, fleshy to ± subcoriaceous, glossy dark green to yellow-green, at senescence turning yellow. Rosette and lower stem leaves withering at fruiting; petioles distinct 40-80 × 1-3 mm, slightly concave in cross-section, fleshy, winged; lamina 60-140 × 15-25 mm, pinnatifid (rarely simple), narrow-oblong to narrow-oblanceolate; pinnae when present in 3-8 pairs, sharply toothed toothed at apex and distal margins, lamina of simple leaves, deeply and unevenly serrated, teeth 1.0-2.2(-5.1) mm long, usually not projecting beyond leaf outline. Middle stem leaves similar (rarely simple) or becoming shallowly pinnatifid, sharply serrate. Upper stem leaves 10-50 × 2-10 mm, narrow-obovate to linear oblanceolate, pinnatifid to simple, sharply toothed at apex and at apex of pinnae if present, cuneate at base; petiole minute or absent. Racemes 10-120 mm long, elongating up to 140 mm at fruiting, terminal and axillary, ± leaf-opposed; rachis glabrous or sparsely hairy; pedicels sparsely hairy, erecto-patent, initially1.3-1.6 mm; elongating to 3-5 mm long at fruiting. Flower buds grass green to dark green, apex glabrous or sometimes bearing a conspicuous, caducous, crest of white, eglandular, antrorse hairs up to 0.9 mm long. Flowers sweetly fragrant, 2.8-3.2 mm diam. Sepals, ovate to oval, apex broadly obtuse, green with a white scarious margin, deeply concave, adaxially weakly keeled, abaxial midrib glabrous or invested in conspicuous, caducous, white, eglandular, antrorse, flexuous hairs, hairs sometimes scattered across rest of abaxial surface; adaxial surface glabrous; lateral sepals 0.8-1.2 × 0.8-1.2 mm, median sepals narrower 0.7-1.0 × 0.6-0.9 mm. Petals white, 0.9-1.4 × 0.6-0.9 mm, erecto-patent, clawed; limb obovate, apex emarginate. Stamens 4, equal. Anthers c.0.12 mm long. Pollen bright yellow. Nectaries 4, subulate, 0.25 mm long. Silicles cartilaginous when fresh, subcoriaceous when dry 2.8-4.0 × 2.3- 3.2 mm, broadly elliptic, slightly winged, apex shallowly notched, valves green maturing pale green, glabrous; style 0.1-0.2 mm long, free from the narrow wing, equal to or slightly exceeding the notch; stigma 0.4 mm diam. Seeds 2, 1.6-2.0 × 1.2-1.8 mm, obovoid, orange-brown, not winged, mucilaginous when wet. FL. Oct-Mar. FR. Nov-Apr.

Representative Specimens.

New Zealand (North Island): Auckland City, Mt Albert, Jesmond Terrace (Naturalised), 9 January 1998, P. J. de Lange 3415, (AK 234450). New Zealand (South Island): North Westland, Punakaiki, Seal Island, 29 December 1991, D. A. Norton s.n., (CANU 36438); Punakaiki, Perpendicular Point, 13 February 1992, P. J. Garnock-Jones 2112 & D. A. Norton, (CHR 470203); Motukikie, January 1995, G. Loh s.n., (CANU 37018); Paringa Knight’s Point, 1 January 1990, D. A. Norton s.n. & J. M. Lord, (CANU 35508); Open Bay Island, January 1909, B. C. Aston s.n., (WELT SP030114); Open Bay Islands, Taumaka Island, 15 February 1992, P. J. Garnock-Jones 2117, (AK 229863, CHR 470208); Open Bay Islands, Taumaka Island, 15 February 1992, P. J. Garnock-Jones 2118, D. A. Norton & amp; D. R. Given, (CHR 470209); Open Bay Islands, Taumaka Island, March 2006, P. I. Knightbridge s.n., (AK 317068-pinnate-leaved form); Open Bay Islands, Taumaka Island, 4 January 2006, P. I. Knightbridge s.n., (AK 317070-simple-leaved form).

Distribution

( Fig. 44 ). Endemic. New Zealand, South Island, (Westland) where it is known from seven sites from Cape Foulwind south to the Open Bay Islands (Taumaka and Popotai). With the exception of the Open Bay Islands, Lepidium naufragorum is scarce within the mainland part of its range. Lepidium naufragorum has also been collected once as a gutter weed in Auckland City, plants having established there from a nearby garden where the species was being cultivated. These naturalised plants persisted for about five years before they died out.

Recognition.

Lepidium naufragorum is easily distinguished from all other Lepidium species in New Zealand by the upright bushy shrub habit (with plants dying down to a central root stock in winter), erect stems, mostly sharply serrated pinnatifid rosette and stem leaves (rarely entire) ( Fig. 55 ), and by the emarginate silicles ( Fig. 56 ). Of the New Zealand species, it is most similar to Lepidium flexicaule in which it was included by Garnock-Jones (1988) before field work and further study recognised its distinctiveness. For differences between Lepidium naufragorum and Lepidium flexicaule , see under Lepidium flexicaule .

Although most plants of Lepidium naufragorum have pinnatifid foliage, occasional specimens with simple or weakly pinnatifid leaves are also known, and these can at times be locally common ( Knightbridge and Newton 2006). It was plants such as these that were the basis for literature records (e.g. Burrows 1972) and collectors such as L. Cockayne and B.C. Aston (WELT!) referring this species to Lepidium oleraceum and Lepidium banksii (as var. ovatum). From Lepidium oleraceum these forms can easily be distinguished by the seasonal growth habit (with plants dying back to the rootstock over winter), and by the distinctly emarginate silicles. So far, Lepidium oleraceum has not been found within the Westland range of Lepidium naufragorum . The confusion with Lepidium banksii partly stems from these early collectors’ uncertainty as to what this species is. In any case, non-pinnate leaved forms of Lepidium naufragorum are readily distinguished from Lepidium banksii by their much smaller (2.8-4.0 × 2.3- 3.2 mm) broadly elliptic and shallowly notched silicles. The silicles of Lepidium banksii are much larger (4.5-5.5 × 4.0-5.0 mm), broadly ovate and deeply notched ( Fig. 25 ).

Ecology.

The ecology of Lepidium naufragorum was described in some detail by Garnock-Jones and Norton (1995) who noted that it preferred sites frequented by seals and nesting sea birds or sea bird roosts. They concluded that the species required these species not only for nutrient enrichment but also because their disturbance kept the habitats of this species open. The authors also noted that Lepidium naufragorum was restricted to base-rich substrates.

Conservation Status.

Lepidium naufragorum has a conservation status of "Threatened / Nationally Vulnerable CD, RR" ( de Lange et al. 2009). Based on current evidence this ranking is still appropriate.

Figures

Figure 25. Mature silicle of Lepidium banksii. CHR 509034. Scale bar = 1 mm.

Figure 44. Distribution of Lepidium flexicaule (New Zealand distribution shown only), Lepidium juvencum, Lepidium limenophylax, Lepidium naufragorum and Lepidium obtusatum.

Figure 55. Mature plant of Lepidium naufragorum on Taumaka Island (image: P. I. Knightbridge)

Figure 56. Inflorescence of Lepidium naufragorum showing mature and immature silicles.