Barleria grootbergensis I.Darbysh. & E.A.Tripp

Darbyshire, I., Tripp, E.A. & Dexter, K.G. Kew Bull (2012) 67: 759. https://doi.org/10.1007/s12225-012-9393-1

Morphology Stem

Mature stems densely white-velutinous, the trichomes minute, declinate, interspersed with occasional longer appressed trichomes; uppermost internodes patent glandular-pubescent

Morphology Reproductive morphology Flowers Calyx

Calyx 4-lobed; abaxial lobe elliptic, 17 – 18.5 × 7 – 8 mm, base cuneate, apex shallowly notched for up to 2.5 mm, surface with 5 – 7 prominent subparallel veins; posticous lobe elliptic, 17.5 – 20 × 6.5 – 7 mm, apex acute or shortly attenuate; lateral lobes lanceolate, ± 11 × 2 mm, margin hyaline

Morphology Reproductive morphology Flowers Androecium Stamens

Stamens attached 7 mm from base of corolla tube; filaments 31 mm long, minutely pubescent at the base; anthers 4 mm long; lateral staminodes to 1.5 mm long, flattened and triangular, minutely pubescent, antherodes absent; adaxial staminode minute

Morphology Reproductive morphology Flowers Pollen

Pollen trizonocolporate, globose in equatorial view, 3-lobed in polar view, with coarse deep reticulation of the interapertural and polar exine

Morphology Reproductive morphology Fruits

Capsule 13 – 16 × 6 – 7 mm, including prominent beak 4 – 6 mm long, beaked portion covered with short glandular and/or eglandular trichomes, fertile portion glabrous; seeds c- 5 – 6 × 4 – 5 [very few seen], covered in non-mucilaginous, crisped hygroscopic trichomes. Capsule 2-seeded, 14 – 18 mm long including beak 5 – 7 mm long, glandular- and eglandular-puberulous; seeds 5.7 – 6.2 × 5.4 – 5.8 mm

Distribution

NW Namibia; known only from the type locality. Endemic to Northwest Namibia (Kunene Region);

Ecology

Growing on rocky slopes including loose scree close to the road; 1400 m alt. Barleria grootbergensis is typically found growing on dry rocky hillslopes and along dry riverbeds, usually in open situations but occasionally in shade of Colophospermum mopane. It occurs at 950 – 1550 m elevation. It is a species of the Kaokoveld Centre of plant endemism (sensu van Wyk & Smith 2001) and is largely restricted to the North-western Escarpment and Inselbergs sub-division of the Nama Karoo vegetation type of Mendelsohn et al. (2002).

Conservation

This species is currently known from a single locality, where it is very localised. Less than 15 plants were seen in the vicinity; however we should note that population size was not assessed in an exhaustive manner. Based on current data, it is apparently highly restricted in its range, having not been collected previously despite being found along one of the main roads between the popular Skeleton Coast and Etosha Pan. However, much of the mountainous region to the north and south of the road over the Grootberg Pass is inaccessible by vehicle and has probably never been botanised. Satellite imagery available on Google Earth (http://www.google.co.uk/intl/en_uk/earth/index.html) suggests that there are extensive areas of potentially suitable habitat for Barleria grootbergensis in this region. Furthermore, there appears to be little threat to the only known population given that the area is generally not heavily travelled. The only habitation in the immediate vicinity is that of a small eco-lodge, which is owned and operated by the Grootberg Conservancy and thus unlikely to significantly impact the population in a negative manner. Whilst this species must currently be considered Data Deficient (DD) (IUCN 2001) pending further survey work, it may ultimately prove to be unthreatened. This species was assessed as Data Deficient in the protologue, when only two collections were known. However, it is now known to be considerably more widespread in the Kaokoveld region with an EOO of 12,300 km2. It occupies dry rocky slopes and riverbeds in arid areas, where human populations and impacts are low. Grazing pressure in some parts of its range may impact seedling recruitment, but this is not considered to be a major threat at present. This species is therefore reassessed here as of Least Concern — LC.

Note

The minute white-velutinous indumentum on the mature stems, the densely glandular inflorescence indumentum and the general facies of the flowers place this species close to Barleria lancifolia T. Anderson, a species that is widespread and common in Namibia. B. grootbergensis is, however, easily separable from B. lancifolia by its dense terminal spikes with the calyces largely hidden within the ± erect yellow-green bracts and bracteoles, the latter subequal in length to the calyces. In B. lancifolia, the cymules are more distantly spaced along the axis, at least in the lower portion of the inflorescence where the bracts are foliaceous. The bracts in the upper portion of the inflorescence in B. lancifolia are greatly reduced and proportionally narrowed (though remaining green) and are more spreading than in B. grootbergensis. The calyces of B. lancifolia are also always clearly exposed (see Fig. 4). The bracteoles in B. lancifolia are generally shorter than the calyx and ≤ 15 mm in length in single-flowered cymules (the lower cymules of the inflorescence are often 3-flowered). Finally, the glandular trichomes of the inflorescence in B. grootbergensis are somewhat longer and more dense (particularly on the bracts) than those of B. lancifolia. The combination of prominently beaked, two-seeded capsules (Fig. 2D), three staminodes lacking antherodes, linear stigmas, absence of spines and non-stellate indumenta place Barleria grootbergensis within section Somalia of Barleria with confidence (Balkwill & Balkwill1997; Darbyshire2009).

Type

Namibia, W of Grootberg Pass, fl. 22 March 2010, Tripp & Dexter 828 (holotype RSA!; isotypes K! [K001290358], NY! [NY01239649], WIND! [WIND000094996]).

Morphology General Habit

Shrub or perennial herb 30 – 100 cm tall; mature stems densely white-velutinous, hairs minute, declinate, interspersed with occasional longer appressed hairs; distal internodes patent glandular-pubescent and with sparser white declinate and appressed hairs Shrub to 100 cm tall

Morphology Leaves

Leaves on petiole 4 – 16 mm long; blade somewhat coriaceous, ovate (-elliptic) or lanceolate, 3.5 – 8 × 1.4 – 3.3 cm, base cuneate, attenuate or obtuse, apex acute, attenuate or rarely obtuse, lateral veins 4 – 5 pairs; leaf buds densely white-strigulose but mature leaves soon-glabrescent except for sparse strigose hairs along the margin, midrib and sometimes lateral veins beneath, some hairs “anvil-shaped” (i.e.biramous with one long arm and one short arm), distal pairs of leaves also glandular-pubescent at least along margin. Leaves ovate or lanceolate, 3.8 – 5.3 × 1.4 – 2 cm, base cuneate, apex acute or attenuate, lateral veins 4 pairs; leaf buds densely white-strigulose but mature leaves soon glabrescent except for sparse strigose trichomes along the margin, midrib and lateral veins beneath, some trichomes ‘anvil-shaped’ (i.e. biramous with one long arm and one short arm), uppermost leaf pairs also glandular-pubescent; cystoliths conspicuous on both surfaces without magnification, sessile glands visible on upper surfaces with magnification; petiole to 6 mm long

Morphology Reproductive morphology Inflorescences

Inflorescences terminal spikes 2 – 8 cm long, often many-flowered and dense throughout or rarely becoming more lax towards base, each cyme within spike single-flowered or cymes at base of spike 3-flowered; bracts, bracteoles and calyces yellow-green to green or bracts sometimes drying darker green-brown; bracts in distal portion of inflorescence held ± erect and (partially) covering the calyces, elliptic or somewhat oblanceolate, rarely lanceolate, 11.5 – 22 × (3 –) 4 – 8.5 mm, apex acute or somewhat attenuate, pairs of bracts towards base of inflorescence often larger and more spreading, typically 21 – 33 × 5 – 15 mm, densely glandular-pubescent throughout; cymes often sessile but lowermost pairs can be pedunculate for up to 3.5 (– 6.5) mm long; bracteoles held ± erect against the calyx, narrowly elliptic, oblanceolate or lanceolate, 15.5 – 20 × 2.5 – 5 mm, apex acute, midrib or sometimes 3 main veins prominent; flowers subsessile. Calyx not markedly accrescent, anterior lobe elliptic or subrhombic, 11 – 19 × 5.5 – 9 mm, base cuneate or attenuate, apex acute or shallowly notched for up to 2.5 mm, surface with 5 – 7 prominent subparallel veins; posterior lobe as anterior lobe but marginally larger, apex acute or shortly attenuate, densely glandular-pubescent; lateral lobes lanceolate, 7 – 13.5 mm long Inflorescences short dense terminal spikes 3.5 – 5 cm long, of a series of subsessile single-flowered opposite cymules; bracts, bracteoles and calyces pale yellow-green, densely glandular-pubescent throughout; bracts caducous in fruit, elliptic (excluding larger basal leaf-like pair), 18 – 22 × 5.5 – 8 mm, apex acute or subattenuate; bracteoles narrowly elliptic or oblanceolate-elliptic, 15.5 – 20 × 2.5 – 5 mm, held erect and ± equalling the calyx, apex acute

Morphology Reproductive morphology Flowers Corolla

Corolla pink, blue or pale purple with whitish throat and tube, 34 – 52 mm long, lateral lobes with numerous to sparse mixed glandular and eglandular hairs externally; tube 17 – 28 mm long, subcylindrical or throat gradually expanded, mouth 3.5 – 6.5 (– 7.5) mm wide; lobes in “4+1” configuration, abaxial lobe offset by 5 – 9 mm from the remaining lobes, broadly obovate, 11 – 18.5 × 7.5 – 14.5 mm, apex emarginate; lateral lobes elliptic-obovate or obovate, 11 – 18.5 × 8 – 14 mm, apices rounded or shallowly emarginate; adaxial lobes narrower, 4.5 – 9.5 mm wide. Stamens inserted c. 7 mm from base of corolla tube; filaments ± 31 mm long; anthers 3.3 – 4.3 (– 4.8) mm long; lateral staminodes to 1.5 mm long, flattened and triangular Corolla pale purple with whitish throat and tube, 48 – 52 mm long, with sparse mixed glandular and eglandular trichomes on the lateral lobes externally; tube 25 – 28 mm long, unexpanded basal portion of the tube ± 3 – 4 mm in diam., gradually expanded above attachment point of stamens to ± 6 – 6.5 mm in diam- at the mouth; lobes in ‘4 + 1’ arrangement, abaxial lobe offset by 9 mm from the remaining lobes, broadly obovate, 17.5 × 14.5 mm; lateral lobes elliptic-obovate, 17 × 13 mm; adaxial lobes elliptic-obovate, 18.5 × 9.5 mm

Morphology Reproductive morphology Flowers Gynoecium Ovary

Ovary densely glandular- and eglandular-puberulous distally; style glabrous; stigma 1.5 – 3 mm long, curved Ovary 4 mm long, distal portion densely mixed glandular- and eglandular-puberulous; style 35 – 43 mm long, glabrous; stigma linear, 2.5 – 2.8 mm long, curved