Delosperma N.E.Brown from Lesotho and neighbouring areas  -  photos of ambiguous species from habitat and dubious plants from cultivation

by Gerhard F. Wagner

The genus Delosperma N.E.Br. (Aizoaceae, Mesembryanthemaceae) is regarded as insufficiently revised. The species of this genus are native to the wetter areas of eastern South Africa, Lesotho and Swaziland, Kenya to Ethiopia, and south-western Arabia, often in high mountain regions. For many of the published species we only know the first description and the deposited herbarium type specimen. In many cases we do not even know the type localities and in many instances the described species were collected only once. From the literature, we only have detailed knowledge of a few species and  in collections Delosperma species with exact locality data are very rare. This unsatisfactory situation pertains particularly for plants from Lesotho and neighbouring areas. Furthermore collections are reported from Lesotho which do not match presently-described Delosperma species and in the horticultural trade Delosperma plants from Lesotho have been sold with completely wrong names. From this we can assume that, particularly in Lesotho, there are different species of Delosperma which are not yet described; a situation which has already been stated by other authors (e.g. Hilliard & Burtt 1987). As an example, several specimens of undescribed Delosperma species from these areas are deposited in the herbarium of the Royal Botanic Gardens, Kew  collected by Hilliard & Burtt.

In this paper some localities of possibly undescribed species are presented together with excellent photos, sometimes also with exact locality data. Unfortunately, more detailed macro-photos and representative plant material from these localities, which would be necessary for exact identifications or new descriptions, are not available. Nevertheless, the photos are so interesting that they are presented here for discussion. Perhaps they might prompt other people to carry out better and more extensive field work in these areas. The author of most of the photos is Edmund Kirschnek from Kolbermoor, Germany, an excellent photographer of succulent plants in southern Africa. He has visited Lesotho and adjoining areas together with Inge Brase from Windhoek, Namibia, a well-known expert in the flora of these areas. The other photos are of cultivated material obtained from the nursery trade. Delosperma plants from high mountainous areas are popular with enthusiasts of alpine plants because they tend to show extreme cold-resistance and also flower in Central Europe, but they are less suitable for warm greenhouses.

Fig.1: Delosperma sp., ca. 50 km NW of Mokhotlong to New Oxbow Lodge, Lesotho, 3100 m. Photo in habitat: E.Kirschnek	Fig.2: Delosperma sp., ca. 16 km NW Sani top, Eastern Lesotho, 3100 m. Photo in habitat: E.Kirschnek	Fig.3: Delosperma sp., ca. 21 km NW Sani top, Eastern Lesotho. Photo in habitat: E.Kirschnek	Fig.4: Delosperma sp. Lesotho. Org.: nursery C.H.Kreß, A-4974 Ort/Innkreis. Photo: G.F.Wagner

Yellow-flowering populations

The presently described, yellow-flowering species from Lesotho are Delosperma nubigenum (Schlechter) L.Bolus and Delosperma rogersii (Schoenland & A.Berger) L.Bolus. To this group, until now, a third species has often been assigned: Delosperma congestum L.Bolus, but the detail given about lemon-yellow flowers in the ‘Sukkulentenlexikon’ (Jacobsen 1955) is an incorrect and misleading translation from the first description in Latin. In this, the colour of the petals is given as white and only in the senescent condition as lemon yellow (L.Bolus 1954). The other characteristics are quoted correctly by Jacobsen, e.g. the slender, acute, densely placed leaves (12-18 mm long, 3 mm broad and thick) and the small diameter of the flowers of about 15 mm. The first description of D. congestum can be found in the appendix of this paper (in Latin), an abridged version is given by Hartmann (2001). D. nubigenum comes from high mountain regions of Lesotho and neighbouring areas of the Drakensberge in KwaZulu-Natal. It has flat, broad and fairly oval, not very acute leaves with a smooth and glossy epidermis. Pictures in Hartmann (2001), S.Hammer & T.Dold (2002) (from Mont aux Sources in north-eastern Lesotho) and G.F.Wagner (2003) give an impression of D. nubigenum. D. rogersii actually is a native of a big area between the Eastern Cape and KwaZulu-Natal, but its distribution area has been supposed to extend over the Sehlabathebe National Park into Lesotho over its south-eastern border. This species is said to be a bigger version of D. nubigenum but with clearly papillose leaves (Hargreaves 1992).

Kirschnek & Brase have taken excellent photos of yellow-flowering species of Delosperma in habitat in Lesotho which do not match presently-described species. Fig.1 depicts a very interesting population found about 50 km north-west of Mokhotlong near the road to Oxbow Lodge at an altitude of about 3100 m. Despite some similarities, there are also clear differences from D. nubigenum. The leaves show an interesting blue-green colour and prove to be clearly papillose under magnification – maybe transitional traits to D. rogersii? Unfortunately, a first attempt to clarify the situation by study of herbarium material was unsuccessful because at the herbarium of the Botanical Museum in Berlin–Dahlem nearly all herbarium sheets of Delosperma (including a collection of D. rogersii) had been lent to the Institut für Allgemeine Botanik in Hamburg to help in Dr.Hartmann’s preparation of the two excellent Aizoaceae volumes of the ‘Illustrated Handbook of Succulent Plants’. Therefore, a more exact examination of these correlations must be deferred until an examination of  herbarium specimens in Kew, Berlin or  South-African herbaria becomes possible.

A completely different appearance is shown by the plants in figs.2 and 3. The photos were taken in areas 16 km and 21 km (respectively) north-west of Sani top in eastern Lesotho (altitude ca. 2800 m). The leaves are much more slender than would be expected for D. nubigenum or D. rogersii and, particularly in fig.2, very papillose. Could the differences be more a result of different habitat conditions? In comparison with the first description of D. congestum the flowers are bigger (estimated diameter about 20-25 mm) and intensely yellow or chrome yellow coloured.

Other dubious plants of unknown origin are sold in the trade as D. spec. Lesotho or erroneously as D. congestum (figs.4 and 5). Moreover, various other species of Delosperma are also offered wrongly under the name D. congestum. While the leaves of the plant shown in fig.4 are big and rather broad, they are small and clearly papillose on the Delosperma shown in fig.5 (hence it shows similarities to the plant in fig.2). But both have big chrome yellow flowers up to 40 mm in diameter, partly white-coloured on the inside. Therefore similarities with D. congestum, based on its first description, are not discernible for these plants. Where do they come from? Or can we here observe results of hybridisation in cultivation? One could come to the assumption that, resulting from the misleading quotation of the flower colour for D. congestum as ‘lemon yellow’ by Jacobsen, all yellow-flowering Delosperma plants, which are different from the better known D. nubigenum, have been identified as D. congestum because of lack of an alternative. To compound matters, taxonomic assignments of Delosperma species from high mountain regions are generally made more difficult by the fact that the appearances of populations of a given species can differ depending on altitude and habitat conditions. Moreover the appearance of the plants changes in cultivation. In addition, the possibility of plant determinations, even from good photos, is generally limited because important traits for identification are nearly always lacking.

Another mysterious use of the species name ‘congestum’ (as ‘congesta’) can be found in E.van Jaarsveld & U.deVilliers Pienaar (2000). Here under the name “Corpuscularia congesta” is pictured a plant, supposedly coming from an area east of Aliwal North and only about 75 km from the south-western border of Lesotho. Indeed, it looks  similar to a Corpuscularia, but the locality is situated far outside the presently known distribution area for that genus. But the taxon “C. congesta” has never been described or recombined from another genus, e.g. from Delosperma to Corpuscularia. In any case the pictured plant has nothing to do with Delosperma congestum, but where did this name comes from? What is this plant supposed to be?

Fig.5: Delosperma „congestum“. Org.: nursery in Belgium. Photo: W.Borgmann, Aachen	Fig.6: Delosperma aff. lavisiae L.Bolus, Witsieshoek Mountain Resort, Photo in habitat: E.Kirschnek	Fig.7: Delosperma aff. caespitosum L.Bolus var. roseum L.Bolus, Witsieshoek Mountain Resort. Photo in habitat: E.Kirschnek	Fig.8: Delosperma sp., near Katse, Bokong Info Centre, central Lesotho, 2980 m. Photo in habitat: E.Kirschnek

Red-flowering populations

For this group, it also turns out that correct identification of populations will only be possible after an extensive revision of the genus Delosperma combined with intensive and specific field work. At present in the literature, there are often misinterpretations and other problems associated with the taxonomic identification of newly-discovered populations or even existing herbarium specimens of Delosperma from Lesotho and neighbouring areas. One reason for this is that several good species are not yet validly described. Figs.6 and 7 show two photos from the Witsieshoek Mountain Resort in the northern Drakensberge, near the northern border with Lesotho (Qua-Qua-District, Free State). The plant in fig.6 probably belongs to the complex of Delosperma lavisiae L.Bolus. D. alticolum L.Bolus, D. obtusum L.Bolus and D. smythiae L.Bolus are possibly synonymous with that species (Hilliard & Burtt 1987, E.Pooley 2003). Fig.7 shows material with similarities to Delosperma caespitosum L.Bolus var. roseum L.Bolus ( = D.caespitosum L.Bolus fa. roseum (L.Bolus) G.D.Rowley), the recorded distribution area of which is actually located in southern KwaZulu-Natal and the Transkei. Notable features of the plant in fig. 7 are the stubby habit and the small flowers. The plants in figs.8-11 cannot be related to any described species. The rather big flowers with the white-coloured centres shown in figs.8 and 9 are reminiscent of Delosperma floribundum L.Bolus, but the plant bodies are completely different. Possibly they belong to the same species. The plants in figs.11 and 12 seem to be similar but they belong to an another species group. Conspicuous in fig.11, are the long pedicels, otherwise identification is made more difficult by the closed flowers. But these plants are absolutely not interested in the difficulties with their taxonomic identification; they flower in order to reproduce themselves and then the cushions present a wonderful sight to behold in the high mountains.

Fig.9: Delosperma sp., ca. 50 km NW of Mokhotlong to New Oxbow Lodge, Lesotho, 3100 m. Photo in habitat: E.Kirschnek	Fig.10: Delosperma sp., ca.16 km NW Sani top, 3100 m. (white flowers: Helichrysum sp.) Photo in habitat: E.Kirschnek	Fig.11: Delosperma sp., ca.21 km NW Sani top, 2800 m. Photo in habitat: E.Kirschnek	Fig.12: Delosperma aff. lineare L.Bolus, Witsieshoek Mountain Resort. Photo in habitat: E.Kirschnek

Populations with white flowers

Fig.12 shows another plant from the Witsieshoek Nature Resort. It is probably Delosperma lineare L.Bolus, which was described from Lesotho without indication of a more specific type locality (Bolus 1928), though the pink-coloured filamentous staminodes and filaments as mentioned in the first description can not be recognised in the photo. According to E.Pooley (1998) this species is also a native of this area. Species of Delosperma with yellow flowers are often erroneously offered in the trade under the name D. lineare, but  represent in reality completely different species. Even D. nubigenum has been distributed for a long time under the wrong names Delosperma dyeri or D. lineare (Wagner 2003). Another population from an area west of Maseru, still on South African territory near the border, is shown in fig.13. Presumably it is Delosperma kofleri Lavis, one of the few white-flowering species which are described from Lesotho. The type locality of this species is Roma, located about 35 km south-east of Maseru (Lavis 1966). The small flowers are characteristic. Finally, fig.14 shows a very interesting undescribed collection from Sani Pass (at the border with KwaZulu-Natal in eastern Lesotho): a Delosperma with small, glossy leaves and a very small white flower. This plant and particularly its flower is reminiscent of Delosperma alpinum (N.E.Br.) S.A.Hammer (syn.: Ectotropis alpina N.E.Br.) from the Eastern Cape, which was recently recombined by Hammer & Dold (2003) from Ectotropis to Delosperma because it possesses all the traits of that genus. This new species (or subspecies of D. alpinum) from Sani Pass was collected about 1994 by Sean Hogan of U.C.Berkeley Botanical Garden, although Hilliard & Burtt had seen this plant much earlier (S.Hammer 2003). It is likely that herbarium specimens of this collection have been deposited in the Kew Herbarium and they need to be examined. Both subspecies of D. alpinum are self-fertile.

Fig.13: Delosperma kofleri Lavis, west of Maseru. Photo in habitat: E.Kirschnek	Fig.14: Delosperma sp., Sani Pass. Plant in cultivation, org.: nursery C.H.Kreß, Photo: G.F.Wagner	Fig.15: Ruschia putterillii (L.Bolus) L.Bolus, near Katsedam, central Lesotho, ca. 2100 m. Photo in habitat: E.Kirschnek	Fig.16: as fig. 15

Other species of Mesembryanthemaceae in Lesotho

Apart from species of Delosperma, only very few species of the Mesembryanthemaceae are residents in Lesotho. At present, only one species from each of the genera Mossia, Chasmatophyllum, Stomatium, Trichodiadema, Hereroa, and two species of Ruschia are known (Hargreaves 1991). Ruschia putterillii (L.Bolus) L.Bolus during its flowering period is a very attractive plant and the photographs shown here were taken at an altitude of 2100 m near Katse dam in central Lesotho (figs.15 and 16).

Acknowledgements:

I wish to thank the owner of the special nursery for hardy plants ‘Sarastro’ in A-4974 Ort/Innkreis, Mr.C.H.Kreß, for putting quite a lot of delosperma plants at my disposal for taxonomic identification, also Mr.W.Borgmann, Aachen (Germany) for sending photos and cuttings of ‘Delosperma congestum’ which he obtained from a nursery in Belgium, and finally Mr.Dr.A.Orlt from the Sprachzentrum of the Humboldt-Universität Berlin for the translation of Latin diagnoses into German. I am particularly indebted to Mrs.Inge Brase, Windhoek (Namibia) and Mr. Edmund Kirschnek, Kolbermoor (Germany) for wonderful co-operation and the supply of excellent photos, and last but not least, Mr.Terry Smale, Epsom Downs (U.K.), for proofreading the manuscript.

References:

BOLUS, L. 1928: Notes on Mesembryanthemum and Allied Genera. The Specialty Press of South Africa, Cape Town. (NM) part I: p.143 (First description: Delosperma lineare).

BOLUS, L. 1954: Notes on Mesembryanthemum and Allied Genera, University of Cape Town. (NM) part III: p.270 (First description: Delosperma congestum).

HAMMER, S. & DOLD, T. 2002: Ectotropis N.E.Br. – Lost, Found, and Fragile. - Haseltonia, 9: 39

HAMMER, S. 2003: personal communication

HARGREAVES, B.J. 1991: Mesembs of Lesotho. - Excelsa, 15: 97

HARTMANN, H.E.K. (Ed.) 2001: Illustrated Handbook of Succulent Plants. Aizoaceae A-E, Springer Verlag, p.191, XXXVI

HILLIARD, O.M. & BURTT, B.L. 1987: The Botany of the Southern Natal Drakensberg,. Annals of Kirstenbosch Botanic Gardens, Vol.15, National Botanic Gardens (SA), p.155

Van JAARSVELD, E. & de VILLIERS PIENAAR, U. 2000: Vygies, Gems of the veld. Cactus & Co., p.77  

JACOBSEN, H. 1955: Handbuch der sukkulenten Pflanzen. VEB Gustav Fischer Verlag Jena, p.1308

LAVIS, M. 1966: J. South African Botany 32: 341 (First description: Delosperma kofleri)

POOLEY, E. 1998: A Field Guide to Wild Flowers, KwaZulu-Natal and the Eastern Region. Natal Flora Publications Trust, Durban, p.136 

POOLEY, E. 2003: Mountain Flowers. A Field Guide to the Flora of the Drakensberg and Lesotho. The Flora Publications Trust, Durban, p.200

WAGNER, G.F. 2003: Leserbrief zu V.Dornig: „Winterharte Sukkulenten ?“ - Avonia 21(1): 9

Gerhard F.Wagner, Lindenhof 9, D-12555 Berlin, e-mail: Wagnerfgas@aol.com

Appendix:

First description: Delosperma congestum L.Bolus, Notes on Mesembryanthemum and Allied Genera, part III. 270 (1954). (Übersetzung aus dem Lateinischen: Dr.A.Orlt, Berlin)

Rami plures visi, erecti ut videtur, ad 13 cm. longi, ad 3 mm. diam., internodiis 0.2—1.5 cm. longis; partes herbaceae glabrae politaeque virides; folia densa, adscendentia vel patenti-adscendentia vel demum patentia, supra plana vel obscure sulcata, acuta, dorso rotundata, lateribus convexis, lat. visa prope apicem angustata acuta, apiculo subnullo, 1.2—1.8 cm. longa, ad 3 mm. lata diametroque; flores 1—2 ternati, cymis congestis (itaque nomen); pedunculi 2—5 mm. longi, intermediis ebracteatis; receptaculum obconicum prope medium plus minusve constrictum, 3—4 mm. longum, ad 4 mm. diam.; sepala 5, dorso rotundata, acuta, 3—4 mm., vel 3—5 mm., vel demum ad 6 mm., longa, basi 1.5—2 mm. lata, 3 membranaceo – marginata; petala 2—3-seriata, sat laxa, inferne haud vel vix angustata, obtusa vel emarginata, alba, marcescentia citrina, 4—6 mm. longa, 0.5—0.75 mm., vel rarius ad 1 mm., lata; staminodia mox apicem versus valde recurvata, basi obscure papillata, alba, superne pallidissime viridia, stamina conice conferta bene excedentia; filamenta 3-seriata, ad 3 mm. longa, exteriora inferne ciliate papillata, intima prope apicem conspicue papillata, antheris sordide luteis; glandulae sat conspicuae, subapproximatae crenulatae; ovarii lobi sat abrupte elevati fere ad 1 mm., subapproximati obtusi; stigmata 5, e basi superne gradatim attenuata, fere ad apicem papillata vel breviter caudata, ad 3 mm. longa.

Eastern Basutoland; Phutaberg, prope Mokhotlong, Jan.1953, L.C.C.Liebenberg (S.U.G. 12957). Fl. Jan.1954.

First description: Delosperma kofleri Lavis, Journ. South African Botany 32: 341 (1966)

Delosperma kofleri Lavis sp. nov. (Angustifolia).—Planta erecta, glabra, 22 cm. diam.; rami primarii lignosi brunnei, ad 13 cm. longi, ad 2.5 mm. diam., internodiis 4—20 mm. longis; ramuli ascendentes vel fere patentes, superne interdum leviter incurvi, saepe pallidi, 2—10 cm. longi, 0.75—1.5 mm. diam. internodiis 4—18 mm. longis; folia ascendentia vel fere erecta, saepe subfalcata supra visa plana vel leviter concava, linearia, superne leviter angustata, acuta, dorso rotundo, viridia, lateraliter visa saepissime acuta, 4—15 mm. longa, medio 2—3 mm. lato diametroque; flores solitarii, ca. 1 cm. diam.; receptaculum obconicum, 3 mm. longum, 4 mm. diam.; pedunculi 3—4 mm. longi; sepala 5, abrupte acuta vel acuta, 3—5, vel extima 5—6 mm., interiora marginata, ad 3 mm., longa, basi 1—1.5 mm. lata; petala ca 2-seriata, infra medium inferne leviter angustata, apice rotundo, alba, 5—6 mm. longa, 1 mm. lata vel parum ultra; staminodia nulla; filamenta 3—4-seriata, epapillata alba, ad 3 mm. longa, antheris pollineque albidis; stigmata anguste subulata, 1.75 mm. longa cum cauda 0.75 mm. longa.

Basutoland: Roma Mission, C. Kofler. NBG 94/63. Fl. Nov. 1964.