Peliostomum leucorrhizum E.Mey. ex Benth.

Kolberg H., van Salgeren M. 2016. A synopsis of Aptosimum and Peliostomum (Scrophulariaceae) in Namibia, including the description of a new species, Aptosimum radiatum, and keys to all accepted species. Kew Bulletin 71:16. DOI 10.1007/S12225-016-9628-7

Conservation

This very widespread species is evaluated as LC here since the EOO and AOO are well above the thresholds for the threatened categories and no additional two criteria are met under criterion B (IUCN 2012, 2013). In South Africa the species has also been evaluated as LC (SANBI 2014).

Ecology

Grows in gravelly to sandy soil of diverse origin, including calcrete, dolerite and granite on plains, slopes, in valleys and watercourses. Recorded from the Kalahari savanna, pans, Karstveld, shrubland, highland savanna, highland shrubland, escarpment and inselbergs, dwarf shrub savanna, desert-dwarf shrub savanna transition, dwarf shrub savanna – Kalahari transition, desert and succulent steppe vegetation types (Mendelsohn et al. 2010). Occurring in the Kaokoveld, Welwitschia Desert, Zambesian Domain, Namib Dune, Southern Namib Succulent Desert, Escarpment, Highlands (to 1500 and 1800 m), Huns-Orange, Gordonia and Kalahari Sands phytogeographical regions of Craven (2009). Altitude: 40 – 2095 m.

Morphology General Habit

Shrub, erect to ascending, 7 – 50 cm tall, sometimes barely woody, not spinescent

Morphology Leaves

Leaves ascending or spreading, narrowly linear-lanceolate, linear, ovate, oblong-obovate, oblong-lanceolate, linear-lanceolate to linear-obovate, (3 –) 15 – 33 (– 38) × 1 – 5 mm, glabrous, subglabrous, minutely puberulent to sparsely glandular pubescent; apex obtuse, subobtuse to acute; base sessile, subsessile to tapering into a 1 – 2 mm long petiole; midrib indistinct

Morphology Reproductive morphology Flowers

Flowers solitary, axillary, along terminal parts of stems, pedicellate; pedicel 1 – 2.5 mm long; bracteoles linear, scale-like, minute, 0.25 – 2 × 0.1 – 0.25 mm, arising near base of pedicel, glabrous

Morphology Reproductive morphology Flowers Androecium Stamens

Stamens 4, not exserted from corolla; filaments glabrous, longer pair 12 – 14 mm long, shorter pair 5 – 12 mm long; anthers equal, minutely pubescent to long white ciliate

Morphology Reproductive morphology Flowers Calyx

Calyx lobed to base, 2 – 5 (– 7.5) mm long; lobes narrowly linear to linear-lanceolate, shorter than capsule, 5 – 6 × 0.25 – 0.5 mm, apex acute to subulate, glabrous, minutely papillose and glandular-pubescent outside and papillose inside

Morphology Reproductive morphology Flowers Corolla

Corolla 12 – 20 mm long, glabrous, sparsely minutely stipitate-glandular to sparsely glandular-pubescent outside; tube funnel-shaped, narrow basally, widening gradually towards mouth, narrow part from much shorter than to longer than calyx, 5 – 8 (– 16) mm long, 2 – 4 mm diam at mouth, mouth slightly oblique, whitish, pale blue, violet to purple with darker venation outside; lobes subcircular, lower c. 4 × 4 mm, others c. 3 × 3 mm, inside blue, violet to purple with darker patch at base

Morphology Reproductive morphology Flowers Gynoecium Ovary

Ovary papillose with some stipitate glands; style papillose at base; stigma capitate, extending to corolla mouth

Morphology Reproductive morphology Fruits

Capsule narrowly ovoid, ovoid-oblong to conical, 5 – 9 × 2.5 – 3 mm, slightly longer than to much longer than calyx; apex subobtuse, shortly beaked to scarcely acute and slightly compressed, minutely papillose

Morphology Reproductive morphology Seeds

Seed reniform, pyramidal to irregular-shaped, irregularly tuberculate, rugose or ridged, cream to orange-brown

Morphology Stem

Stems erect, slender, rigid, much-branched near ground level, sparsely branched above, quadrangular, longitudinally ridged or grooved towards apex, to 1.5 mm diam., glabrous, subglabrous, minutely scaberulous to sparsely glandular-pubescent on green parts; bark white, corky at base

Note

Bentham worked from Kew and type specimens seen by him are therefore expected to be in K, but we could not find a Drège specimen of Peliostomum leucorrhizum from the type locality in this herbarium. Drège s.n. (P-3412911) is selected as lectotype here because it is a complete, good quality specimen and has a label in the collector’s handwriting. Rautanen 38 at Z is selected as lectotype of P. leucorrhizum var. linearifolium over the only other syntype that could be found, Fleck 155a (Z), because of the better quality of the specimen.

As already noted by Merxmüller & Roessler (1967: 38), the distinction between Peliostomum leucorrhizum and P. lugardiae is very difficult, if not impossible, especially in specimens from central Namibia. Leaf shape gradually changes from short and ovate to lanceolate in the south of the country (closer to P. leucorrhizum) to longer and narrowly lanceolate or linear in the north (closer to P. lugardiae). The anthers of P. leucorrhizum are not always so clearly long ciliate or bearded that they could always be separated from the shortly pubescent anthers of P. lugardiae. We therefore concur with Merxmüller & Roessler and treat P. lugardiae as synonym of the older P. leucorrhizum.

Phenology

Flowering and fruiting throughout the year. Peak flowering: Feb. – Sept. Peak fruiting: March – Sept.

Type

Type: South Africa, on the Gariep [III b 7], Drège s.n. (lectotype P-3412911!, selected here; isolectotypes HBG-512065!, P-4432491!, REG-481!, S-08-269!, S-G-4655!).

Vernacular

Rotzunge, Blauglöckchen (German, Namibia); taa (Naro, Namibia).